Dissertations / Theses: 'DIRECT LASER WRITING LITHOGRAPHY'

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Buse, Hauke. "Micro- and sub-microstructuring and characterisation of technical surfaces by means of laser direct writing including a novel approach for laser beam profiling." Thesis, Loughborough University, 2011. https://dspace.lboro.ac.uk/2134/8361.

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Within recent years, numerous fields of engineering, like mechanics, optics and electronics, have been influenced and revolutionised by the technique of microand nano-structuring. For example, special optical elements for beam shaping, surface structures for the reduction of friction or modern "lab on chip" devices have been produced. Within this thesis a universal system has been developed facilitating the production of such structured surfaces with dimensions down to 500 nm. This system is not only capable of structuring surfaces by means of lithographic processes; it further allows the inspection of surfaces by scanning their topography. To realise such a system, two different technologies have been evaluated: Scanning Near-field Optical Lithography (SNOL), a very sophisticated technique which uses a thin fibre tip to expose a photo resist-covered surface, and confocal scanning technology. Here, the confocal scanning is accomplished using an adapted optical component, the optical pickup unit (OPU), from a gaming console, which turned out to be the most suitable and cost-efficient solution for the realisation of this system. Several test series have been carried out during this work, to verify the performance of the confocal system, both to structure photo resist surfaces and to characterise unknown surfaces. This present work will show the ability of the developed system to produce structures down to the sub-micron range and to characterise unknown surfaces with sub- micron precision. Various patterns have been written into photo resistcoated substrates to structure their surface. Beginning with diffractive optical elements (DOE) for beam shaping, followed by Dammann gratings for twodimensional beam shaping and optical gratings for light guidance as well as producing technical surfaces imitating the properties of sharkskin or simple micromechanical structures, the developed confocal system has shown itself to be flexible and widely-applicable. IV During the development of the confocal system, a strong need for a beam profiling system analysing the light beam diverging from the OPU, was recognised. Due to the fact that no commercially available system was capable of characterising beam sizes within the range of the diffraction limit, a novel method for beam profiling was invented. This method makes use of the fibre tips already applied within the SNOL system, producing tomographical scans of the beam spot.

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Bagheri, Shahin [Verfasser], and Harald [Akademischer Betreuer] Giessen. "Large-area plasmonics and sensors : fabrication of plasmonic nanostructures by laser interference lithography and femtosecond direct laser writing / Shahin Bagheri ; Betreuer: Harald Giessen." Stuttgart : Universitätsbibliothek der Universität Stuttgart, 2017. http://d-nb.info/1132583144/34.

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Abou, Khalil Alain. "Direct laser writing of a new type of optical waveguides and components in silver containing glasses." Doctoral thesis, Université Laval, 2019. http://hdl.handle.net/20.500.11794/33849.

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"Thèse en cotutelle, Doctorat en physique; Université Laval, Québec, Canada et Université de Bordeaux, Talence, France"
L'inscription laser directe est un domaine de recherche en croissance depuis ces deux dernières décennies, fournissant un moyen efficace et robuste pour inscrire directement des structures en trois dimensions (3D) dans des matériaux transparents tels que des verres en utilisant des impulsions laser femtosecondes. Cette technique présente de nombreux avantages par rapport à la technique de lithographie, qui se limite à la structuration en deux dimensions (2D) et implique de nombreuses étapes de fabrication. Cela rend la technique d’inscription laser directe bien adaptée aux nouveaux procédés de fabrication. Généralement, l’inscription laser dans les verres induit des changements physiques tels qu'un changement permanent de l'indice de réfraction localisé. Ces modifications ont été classées en trois types distincts:(type I, type II et type III). Dans ce travail, nous présentons un nouveau type de changement d'indice de réfraction, appelé type A qui est basé sur la création d’agrégats d'argent photo-induits. En effet, dans des verres dans lesquels sont incorporés des ions argent Ag+, lors de leur synthèse, l’inscription laser directe induit la création d’agrégats d’argent fluorescents Agmx+ au voisinage du voxel d’interaction. Ces agrégats modifient localement les propriétés optiques comme la fluorescence, la non-linéarité et la réponse plasmonique du verre. Ainsi, différents guides d'ondes, un séparateur de faisceau 50-50, ainsi que des coupleurs optiques ont été inscrits en se basant sur ce nouveau type A et complétement caractérisés. D'autre part, une étude comparative entre les deux types de guides d'ondes (type A et type I) est présentée, tout en montrant qu’en ajustant les paramètres laser, il est possible de déclencher soit le type I soit le type A. Enfin, en se basant sur des guides d’ondes de type A inscrits proche de la surface du verre, un capteur d'indice de réfraction hautement sensible a été inscrit dans une lame de verre de 1 cm de long. Ce capteur miniaturisé peut présenter deux fenêtres de détection d’indice, ce qui constitue une première mondiale. Les propriétés des guides d'ondes inscrits dans ces verres massifs ont été transposées à des fibres en forme de ruban, du même matériau contenant de l'argent. Les résultats obtenus dans ce travail de thèse ouvrent la voie à la fabrication de circuits intégrés en 3D et de capteurs à fibre basés sur des propriétés optiques originales inaccessibles avec des guides d’onde de type I standard.
Direct Laser Writing (DLW) has been an exponentially growing research field during the last two decades, by providing an efficient and robust way to directly fabricate three dimensional (3D) structures in transparent materials such as glasses using femtosecond laser pulses. It exhibits many advantages over the lithography technique, which is mostly limited to two dimensional (2D) structuring and involves many fabrication steps. This competitive aspect makes the DLW technique suitable for future technological transfer to advanced industrial manufacturing. Generally, DLW in glasses induces physical changes such as permanent local refractive index modifications that have been classified under three distinct types: (Type I, Type II & Type III). In silver containing glasses with embedded silver ions Ag+, DLW induces the creation of fluorescent silver clusters Agmx+ at the vicinity of the interaction voxel. In this work, we present a new type of refractive index change, called type A occurring in the low pulse energy regime that is based on the creation of the photo-induced silver clusters allowing the creation of new linear and nonlinear optical waveguides in silver containing glasses. Various waveguides, a 50- 50 Y beam splitter, as well as optical couplers, were written based on type A modification inside bulk glasses and further characterized. In addition, a comparitive study between type A and type I waveguides is presented, showing that finely tuning the laser parameters allows the creation of either type A or type I modifications inside silver containing glasses. Finally, based on type A near-surface waveguides, a highly sensitive refractive index sensor is created in a 1 cm glass chip, which could exhibit a pioneer demonstration of double sensing refractive ranges. The waveguiding properties observed and reported in the bulk of such silver containing glasses were transposed to ribbon shaped fibers of the same material. Those results pave the way towards the fabrication of 3D integrated circuits and fiber sensors with original fluorescent, nonlinear and plasmonic properties that are not accessible using the standard type I modification.

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Florian, Baron Camilo. "Laser direct-writing for microfabrication." Doctoral thesis, Universitat de Barcelona, 2016. http://hdl.handle.net/10803/400403.

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Digital manufacturing constitutes a real industrial revolution that is transforming the production processes from the early stages of research and development to mass production and marketing. The biggest difference in comparison with old fabrication methods is the possibility to perform changes in the pattern design just by using mouse clicks instead of modifying an already fabricated prototype, which results in faster, cheaper and more efficient fabrication processes. For example, new technologies enabling the production of printed electronic devices on flexible substrates and compatible with roll-to-roll processing methods would result in cheaper fabrication costs than the traditional batch processing of silicon wafers. Such fabrication methods comprise a series of processing steps which are applied to the substrates while they are moving on rolls in the fabrication line. Therefore, it is desired that the new technologies can work at high speeds allowing at the same time the production of miniaturized features. Lasers are a versatile tool that can meet the demands of flexibility, speed, resolution and compatibility with roll-to-roll processing of digital manufacturing. The main advantages of laser radiation rely in its unique properties: high directionality, coherence and monochromaticity. The combination of such properties allows generating high intensities that can be focused into extremely small volumes, which makes lasers an ideal tool for the processing of materials at the micro- and nano-scale, not only as a subtractive but also as an additive technique. Laser ablation is the best known subtractive technique and it consists in the irradiation of a material with a focused laser beam. In the case of working with transparent materials, surface ablation constitutes a serious challenge since it is necessary to develop new strategies that allow controlling the position where the energy is delivered to ensure that ablation really occurs in the surface without modifying the bulk material. On the other hand, lasers can also be used as additive tools. For example, laser-induced forward transfer (LIFT) allows the transfer of materials in both solid and liquid state with high spatial resolution. In spite of the extensive amount of research on LIFT, some challenges still remain. For instance, the understanding of the particular printing dynamics encountered during the high speed printing of liquids, or the problem of printing uniform, continuous and stable lines with high spatial resolution. The objective of this thesis is to propose and implement feasible solutions to some of the challenges that are associated with both the subtractive and additive laser based techniques presented above. On one side, we study the laser ablation of transparent polymers using femtosecond laser pulses with the aim of achieving spatial resolutions that overcome the diffraction limit, and at the same time solving the problem of the required precise focusing of the laser beam on the materials surface. On the other side, we study the LIFT transfer dynamics during the high speed printing of liquids, and we propose alternative printing strategies to solve the inherent quality defects usually encountered during the formation of printed lines. Finally, two different approaches that are a combination of both subtractive and additive techniques are presented; we implement LIFT for the fabrication of liquid microlenses used for the surface nanopatterning of materials, and on the other side, we create fluidic guides by laser ablation for the printing of high quality continuous lines.
La fabricació digital de dispositius tecnològics requereix el desenvolupament de noves i millors tècniques per al microprocessament de materials que al mateix temps siguin compatibles amb mètodes de producció en sèrie a gran escala com el roll-to-roll processing. Aquestes tècniques han de complir certs requisits relacionats amb la possibilitat de realitzar canvis de disseny ràpids durant el procés de fabricació, alta velocitat de processament, i al mateix temps permetre la producció de motius de forma controlada amb altes resolucions espacials. En la present tesi es proposen i implementen solucions viables a alguns dels reptes presents a la microfabricació amb làser tant substractiva com additiva. D'una banda, es presenta un nou mètode d'enfocament del feix làser sobre la mostra per l'ablació superficial de materials transparents que permet obtenir resolucions espacials que superen el límit de difracció del dispositiu òptic. D'altra banda, es duu a terme un estudi de la dinàmica de la impressió de líquids mitjançant làser a alta velocitat, de gran interès de cara a la implementació industrial de la tècnica. A més, es presenten estratègies d'impressió de tintes conductores amb l'objectiu de produir línies contínues amb alta qualitat d'impressió. Finalment s'inclouen dues propostes que són producte de la combinació d’ambues tècniques, la impressió de líquids i l'ablació amb làser.

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Heathcote, Robert. "Synthesis and application of organogold precursors for direct laser writing." Thesis, Keele University, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.502939.

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Park, Chang-Hyun. "Study on nonlinear multi-dimensional direct laser writing by using ultrashort high power laser." Thesis, Bordeaux, 2020. http://www.theses.fr/2020BORD0046.

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Au cours des 30 dernières années, alors que la largeur d'impulsion des lasers a été réduite et que les lasers haute puissance ont été développés, des recherches sur l'interaction entre le photon et les matériaux utilisant des lasers femtosecondes ont été activement menées. La haute densité d'énergie des lasers pulsés femtosecondes permet des processus de photoionisation non linéaire de plusieurs manières selon. Cet article rapporte une étude d'une écriture laser directe de type Argentum dans des verres de phosphate de zinc contenant de l'argent en induisant une déformation d'absorption non linéaire d'impulsions laser femtoseconde. Lorsque des verres de phosphate de zinc contenant de l'argent sont irradiés avec des impulsions laser femtoseconde, des amas en forme d'anneau se forment en raison d'une absorption non linéaire. Les propriétés de fluorescence et l'indice de réfraction de l'amas d'argent induit par cette déformation sont différents de ceux du verre d'origine.Des comparaisons simultanées de microsondes chimiques, de NSOM et de modélisation numérique ont été utilisées pour analyser la distribution des espèces d'argent induite par laser. Les résultats renforcent considérablement la compréhension des modifications matérielles de ces verres dans un régime d'interaction non thermique. En particulier, il a été constaté que la distribution spatiale des espèces dans des verres contenant de l'argent produits par irradiation laser femtoseconde a un effet significatif sur la sélectivité de la gravure chimique.Les séparateurs de faisceau en forme de Y, des structures 2D fabriquées à l'aide de DLW de type A, ont été fabriqués et leurs performances ont été mesurées. Il a été confirmé qu'un guide d'onde de forme générale dans laquelle l'indice de réfraction du noyau est plus grand que celui du revêtement peut être produit par le biais d'un DLW de type A. Étant donné que le DLW de type A induit toujours des changements d'indice de réfraction positifs de 2,7 x 10-3 à 5,1 x 10-3, il est très approprié pour fabriquer un guide d'onde. Une jonction Y symétrique et diverses jonctions Y asymétriques ont été conçues et fabriquées à l'aide de guides d'ondes à double ligne, et les rapports de sortie ont été mesurés en fonction de la transition de la position d'injection. Il a été confirmé que le ratio de sortie pourrait être de 96% -4% à 57% -43% en raison de l'irradiance différente dans le processus d'écriture entre la branche supérieure et la branche inférieure. Ainsi, les verres DLW en argent contenant du phosphate de zinc peuvent être utilisés facilement et rapidement pour fabriquer le type de dispositif optique souhaité avec uniquement le processus d'écriture.Enfin, en recherchant le stockage optique de données 5D (ODS) à l'aide de DLW de type A, le champ d'application a été élargi. Nous avons démontré le stockage optique de données 5D encodé dans des modifications orientées DLW de type A en utilisant un rayonnement laser relativement faible par rapport au DLW conventionnel. Cinq dimensions ont été obtenues en ajoutant l'orientation du motif d'ellipse et l'intensité de fluorescence à la position 3D. Le motif d'ellipse a été créé par mise au point anamorphique, et l'orientation a été ajustée à 16 niveaux en utilisant SLM. De plus, un dispositif AOM a été utilisé pour régler l'irradiance laser femtoseconde de 16 niveaux.Pour confirmer la possibilité du 5D ODS proposé, deux images différentes ont été simultanément intégrées dans une image par DLW de type A. Et les deux images originales différentes au format bitmap 4 bits ont été restaurées avec succès. Les fidélité de lecture correspondantes de 60,5% et 25,1% ont été obtenues pour la direction d'orientation et les niveaux d'intensité de fluorescence, respectivement. De plus, il est démontré que la précision de lecture peut être considérablement améliorée à 85,0% et 47,1% lorsque le format bitmap 3 bits a été appliqué. [...]
In the past 30 years as the pulse width of lasers has been narrowed and high-power lasers have been developed, researches on the interaction between photon and materials using femtosecond lasers have been actively conducted. The high energy density of femtosecond pulsed lasers enables nonlinear photoionization processes in several ways depending. This paper reports a study of a type Argentum direct laser writing in silver containing zinc phosphate glasses by inducing a nonlinear absorption deformation of femtosecond laser pulses. When silver-containing zinc phosphate glasses are irradiated with femtosecond laser pulses, ring-shaped clusters are formed due to non-linear absorption. The fluorescence properties and the refractive index of the silver cluster induced by this deformation are different from those of the original glass.Simultaneous comparisons of chemical micro probes, NSOM and numerical modeling were used to analyze the laser-induced silver species distribution. The results significantly strengthen the understanding of material modifications in such glasses in a non-thermal interaction regime. In particular, it has been found that the spatial distribution of species in silver-containing glasses produced by femtosecond laser irradiation has a significant effect on chemical etching selectivity.The Y-shaped beam splitters, 2D structures made by using type A DLW, was fabricated and its performance was measured. It was confirmed that a waveguide of a general shape in which the refractive index of the core is larger than that of cladding can be produced through type A DLW. Since the type A DLW always induces positive refractive index changes from 2.7x10-3 to 5.1x10-3, it is very suitable for making waveguide. A symmetric Y-junction and various asymmetric Y-junctions were designed and fabricated using double line waveguides, and the output ratios were measured according to the transition of the inject position. It was confirmed that the output ratio could be from 96%-4% to 57%-43% due to the different irradiance in the process of writing between the upper branch and lower branch. So DLW in silver containing zinc phosphate glasses can be utilized easily and quickly to fabricate the desired type of optical device with only the writing process.Finally, by researching 5D optical data storage (ODS) using type A DLW, the scope of application was further expanded. We have demonstrated 5D optical data storage encoded in orientated type A DLW modifications by using a relatively low laser irradiance compared to conventional DLW. Five dimensions were achieved by adding the orientation of ellipse pattern and fluorescence intensity to 3D position. The ellipse pattern was created by anamorphic focusing, and the orientation was adjusted to 16 levels by employing SLM. In addition, AOM device was used to adjust the femtosecond laser irradiance of 16 levels.To confirm the possibility of the proposed 5D ODS, two different images were simultaneously embedded in one image by type A DLW. And the two different original images of 4-bit bitmap format were successfully restored. The corresponding reading fidelities of 60.5% and 25.1% were obtained for the orientation direction and fluorescence intensity levels, respectively. In addition, it is shown that the reading accuracy can be greatly improved to 85.0% and 47.1% when 3-bit bitmap format was applied. Using the proposed this technology, we have reached a maximum data density of 14.9 Gb/cm3, and we believe that data storage densities of up to 119.2 Gb/cm3 (using NA = 1.3 oil target) can be achieved.In conclusion, the fluorescence characteristics of type A DLW in silver containing zinc phosphate glasses were studied, and its utility as a multi-dimension application was confirmed. We believe this technology has great potential for nano-scale patterning in semiconductor and fabrication of micro-scale optical devices

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Tian, Jing. "Femtosecond laser direct writing of circular optical properties in silica glass." Thesis, université Paris-Saclay, 2020. http://www.theses.fr/2020UPASF038.

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L'écriture directe par laser femtoseconde (FLDW) permet de créer des modifications permanentes fortement localisées en 3D dans les matériaux transparents. Certains aspects de l'interaction lumière-matière sont fondamentalement nouveaux. Ici, la matière et la lumière sont en interaction produisant une auto-organisation structurée du plasma en cohérence le faisceau laser et ses propriétés vectorielles. Après l'impulsion, cette distribution de densité électronique est "imprimée" en piégeant des électrons dans le solide et un champ de contraintes local peut même être stocké. Celle-ci peut être utilisée comme source par l'impulsion suivante assurant ainsi un « effet mémoire ». Dans cette opération, le solide est restructuré par le champ de force créé par le laser. On peut donc imaginer l'orientation des modifications structurales telles que la décomposition d'oxydes solidifiés directionnellement, la formation de nanocristaux orientés ou encore la création de structures chirales. C'est une nouvelle physique. Mais pour la chimie aussi, il y a de nouveaux aspects car les processus passent par des états fortement excités, largement hors équilibres. Il est donc nécessaire de remettre en question certaines idées précédentes pour comprendre l'excitation et la relaxation de la matière puis de contrôler la structure du produit. Récemment, ces propriétés ont été exploitées avec succès pour de multiples applications pratiques, notamment des optiques biréfringentes, la microfluidique, l'holographie sélective de polarisation et le stockage de données optique ultrastable ouvrant la porte à l’impression laser de circuits photoniques entièrement intégrés. Cependant, plusieurs verrous technologiques cruciaux empêchent son développement: la création de propriétés optiques non linéaires du second ordre et l'impression d'un pouvoir rotatoire toutes deux avec une orientation correcte en 3D.Outre l'impression bien connue d’une forte biréfringence linéaire et d’un dichroïsme linéaire principalement dues à la formation de nanoréseaux, les résultats de ces travaux de thèse établissent qu'un faisceau laser femtoseconde polarisé linéairement et focalisé dans un verre sous une géométrie axialement symétrique est capable de briser la symétrie chirale. Ici, le matériau (un verre de silice, SiO₂) est achiral, mais l'irradiation laser femtoseconde donne en fait lieu à une propriété optique chirale, c'est-à-dire qu'un pouvoir rotatoire important est signalé pour la première fois. De plus, nous produisons une rotation optique avec un contrôle du signe de la chiralité en contrôlant l'angle entre la polarisation linéaire et la direction de balayage du laser. Un dichroïsme circulaire significatif apparaît également proche de la valeur trouvée pour les molécules organiques. Nous avons suggéré une tentative d'interprétation qui implique l'action d'un couple induit par la lumière sur la matière portant un moment diélectrique induit par la lumière, qui pourrait induire une chiralité moléculaire. Une autre explication est basée sur la biréfringence linéaire interne qui pourrait créer un pouvoir rotatoire au travers d’un assemblage non orthogonal non parallèle de deux (ou plus) contributions linéaires.L’écriture directe par laser femtoseconde offre donc ici un nouvel avantage, en partie de manière non conventionnelle: il permet de restructurer notre matériau optique, pour permettre non seulement l'impression de propriétés anisotropes linéaires mais aussi de propriétés optiques chirales. De façon biomimétique, on peut imaginer produire des dispositifs optiques analogues à cristaux liquides cholestériques en utilisant de minuscules longueurs de verre inorganique c'est-à-dire du verre de silice « twisté ou torsadé». Ces propriétés optiques circulaires pourraient jouer un rôle crucial dans les dispositifs optoélectroniques, la détection biologique et la chimie analytique
Femtosecond Laser Direct Writing (FLDW) allows 3D highly localized permanent modifications of transparent materials with minimal collateral damages. To date, no other manufacturing process has the potential to integrate 3D multifunctional devices made in a single monolithic chip and within a variety of transparent materials. Some aspects of the light-matter interaction are fundamentally new. Solid and plasma coexist for a fraction of picoseconds. In addition, both matter and light interact, resulting to the structuration and shaping of the induced plasma. Here the solid intervenes as a source of electrons. Its microstructure organizes the plasma in coherence with that of the light beam and its vectorial properties (e.g., polarization and its distribution). Then, following the light pulse energy deposition inside the matter, this electron density distribution is "imprinted" by trapping electrons in the solid. A localized stress field can also be stored. The latter can serve as a “source” for the next pulse, thus ensuring a memory effect. In this operation, the solid is restructured by the force field created during the laser irradiation. We can therefore imagine the orientation of the structural modifications like oriented nanostructures (so-called nanogratings), directionally solidified oxide decomposition, oriented nanocrystals or even chiral structures. This is a new physics. But from a chemistry standpoint, there are new aspects to explore as well, since the processes involved are performed in highly excited states, and largely off equilibrium. It is therefore necessary to question some previous ideas for understanding matter excitation and relaxation, and then to control the laser-induced structure and properties. Recently, these properties were successfully harnessed for multiple practical applications, including polarization optics, microfluidics, polarization selective holography and ultra-stable optical data storage opening the door towards all-integrated photonics circuits. However, several technological critical limitations prevent further developments among which 1) the creation of second order non-linear optical properties and 2) imprinting some optical rotation, both with tunable orientation in 3D.Apart the well-known imprinting of linear birefringence and dichroism mostly due to the formation of nanogratings, the results establish that a linearly polarized femtosecond laser beam focused inside a glass, and under an axially symmetric geometry, is able to break the chiral symmetry of the material. Here, the material is a silica glass and therefore achiral, but femtosecond laser irradiation actually gives rise to a chiral optical property, i.e., a significant optical rotation. This is reported for the first time. Additionally, we were able to induce optical rotation and to control the chiral sign by tuning the angle between the linear polarization direction and the scanning direction. A significant circular di-attenuation also appears that is close to the value found for organic molecules. We suggested a tentative interpretation that involves the action of a light-induced torque on the matter carrying a light-induced dielectric moment that could induce molecular optical activity. Another suggested explanation is based on internal linear birefringence that could be related to a non-parallel and non-orthogonal assembly of two (or more) linear contributions.Thus, in this context FLDW offers a new advantage, partly in a non-conventional way: it allows restructuring of our most important optical materials, to enable the imprinting of anisotropic linear optical properties but also chiral optical properties. In a biomimetic way, we can envision the fabrication of cholesteric liquid crystal analogous optical devices using tiny lengths of inorganic glass i.e. “twisted silica glass”. Such circular optical properties could play a determining role in optoelectronic devices, biological sensing, and analytical chemistry

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Kang, Seungyeon. "Femtosecond laser direct writing of 3D metallic structures and 2D graphite." Thesis, Harvard University, 2014. http://dissertations.umi.com/gsas.harvard:11495.

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This thesis explores a novel methodology to fabricate three dimensional (3D) metal-dielectric structures, and two dimensional (2D) graphite layers for emerging metamaterials and graphene applications. The investigations we report here go beyond the limitations of conventional fabrication techniques that require multiple post-processing steps and/or are restricted to fabrication in two dimensions. Our method combines photoreduction mechanism with an ultrafast laser direct writing process in innovative ways. This study aims to open the doors to new ways of manufacturing nanoelectronic and nanophotonic devices. With an introductory analysis on how the various laser and chemical components affect the fabrication mechanism, this dissertation is divided into three sections.
Engineering and Applied Sciences

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Vora, Kevin Lalitchandra. "Three-dimensional nanofabrication of silver structures in polymer with direct laser writing." Thesis, Harvard University, 2014. http://dissertations.umi.com/gsas.harvard:11335.

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This dissertation describes methodology that significantly improves the state of femtosecond laser writing of metals. The developments address two major shortcomings: poor material quality, and limited 3D patterning capabilities. In two dimensions, we grow monocrystalline silver prisms through femtosecond laser irradiation. We thus demonstrate the ability to create high quality material (with limited number of domains), unlike published reports of 2D structures composed of nanoparticle aggregates. This development has broader implications beyond metal writing, as it demonstrates a one-step fabrication process to localize bottom-up growth of high quality monocrystalline material on a substrate. In three dimensions, we direct laser write fully disconnected 3D silver structures in a polymer matrix. Since the silver structures are embedded in a stable matrix, they are not required to be self-supported, enabling the one-step fabrication of 3D patterns of 3D metal structures that need-not be connected. We demonstrate sub-100-nm silver structures. This latter development addresses a broader limitation in fabrication technologies, where 3D patterning of metal structures is difficult. We demonstrate several 3D silver patterns that cannot be obtained through any other fabrication technique known to us. We expect these advances to contribute to the development of new devices in optics, plasmonics, and metamaterials. With further improvements in the fabrication methods, the list of potential applications broadens to include electronics (e.g. 3D microelectronic circuits), chemistry (e.g. catalysis), and biology (e.g. plasmonic biosensing).
Engineering and Applied Sciences

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Moebius, Michael. "Applications of Nonlinear Optics in 3D Direct Laser Writing and Integrated Nanophotonics." Thesis, Harvard University, 2016. http://nrs.harvard.edu/urn-3:HUL.InstRepos:33493316.

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This thesis presents novel applications of nonlinear optics in laser fabrication and sources of entangled photons for quantum optics. Femtosecond direct laser writing in transparent media enables mask-less fabrication of sub-micrometer scale features with flexibility in feature shape and position in the x, y, and z-directions. Different applications in optics can be enabled by working in a variety of material platforms. We explore direct laser writing of metal structures in polymer matrices for applications in diffraction optics and modification of hydrogenated amorphous silicon (a-Si:H) for integrated optical devices. These topics explore how nonlinear optical interactions are applied to alter material properties using light. Conversely, nonlinear interactions can be used for wavelength conversion. Nonlinear interactions in nanoscale waveguides can be leveraged to produce efficient sources of entangled photons for applications in quantum optics. We explore using a novel photonic platform, titanium dioxide (TiO2), to realize third-order spontaneous parametric down-conversion (TOSPDC) for direct generation of entangled photon triplets. There is a need for new fabrication techniques that enable true 3D fabrication on the sub-micrometer scale. Diffraction optical elements have many potential applications in imaging, wavelength selection, and dispersion compensation. Multi-layer diffraction optical elements could be used to integrate imaging systems on-chip for lab-on-chip devices, such as microfluidic systems. We explore using 3D laser-written metal structures in polymer matrices for 3D gratings and diffractive elements, such as zone plates and pinholes. We demonstrate diffraction from 3D gratings and imaging using zone plates. 3D fabrication of waveguides has enabled fabrication of complex optical systems within optical fibers and bulk glasses. We explore using femtosecond laser interactions with hydrogenated amorphous silicon to introduce refractive index changes. a-Si:H could be directly integrated with CMOS devices and has the potential for much higher index contrast than bulk glasses, enabling dense, multi-layer optical devices. Efficient sources of three or more entangled photons are necessary for advances in quantum photonics. Current techniques are highly limited because they rely on cascaded second order down-conversion processes to produce entangled photon triplets and often are based in bulk optics. We leverage the high transparency, high linear refractive index, and high chi(3) nonlinearity in TiO2 to develop integrated, on-chip nano-scale waveguide sources of entangled photon triplets via TOSPDC. We present the phase-matching and nonlinear overlap conditions necessary and explore important experimental design considerations.
Engineering and Applied Sciences - Applied Physics

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11

Quick, Alexander Simon [Verfasser], and C. [Akademischer Betreuer] Barner-Kowollik. "Functional Microstructures via Direct Laser Writing / Alexander Simon Quick. Betreuer: C. Barner-Kowollik." Karlsruhe : KIT-Bibliothek, 2015. http://d-nb.info/1077821859/34.

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12

Deubel, Markus [Verfasser]. "Three-Dimensional Photonic Crystals via Direct Laser Writing: Fabrication and Characterization / Markus Deubel." Aachen : Shaker, 2006. http://d-nb.info/1186584416/34.

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13

Anderson, Troy P. "Fabrication of integrated optofluidic circuits in chalcogenide glass using femtosecond laser direct writing." Doctoral diss., University of Central Florida, 2010. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/4579.

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Femtosecond laser direct writing (FLDW) is a versatile process that uses focused femtosecond pulses to modify the physical structure of a material, which can result in a shift of optical properties such as the linear and nonlinear refractive index. If the photon energy of the femtosecond pulses lies below the material bandgap, nonlinear absorption rather than linear absorption becomes the dominant mechanism of energy transfer to the material. In this manner, a focused femtosecond pulse train can be used to fabricate functional features such as optical waveguides, diffractive optical elements, or micro-fluidic elements within the volume of a transparent medium. In this dissertation, the utility of femtosecond laser processing as a fabrication technique of optical and micro-fluidic elements in chalcogenide glasses is explored. The photo-induced modifications of optical and chemical parameters of new germanium-based Chalcogenide glasses in both bulk and thin-film form are characterized for the first time and the impact of material composition and laser fabrication parameters are discussed. The glasses are found to display an increase in volume, a decrease of the linear optical refractive index, and an increase of the nonlinear refractive index when exposed to femtosecond laser pulses. A model based on avalanche ionization and multi-photon ionization is used to describe the highly nonlinear absorption of laser light in the material and correlate the photo-induced modifications to the electron density generated during irradiation. The magnitude of the induced photo-modification is shown to be dependent on laser parameters such as laser dose and repetition rate. The fabrication of microfluidic elements through both direct ablation and the preferential etching of photo-modified regions is also explored. Finally, the integration of both optical elements and fluidic elements fabricated by FLDW into a single substrate is discussed.
ID: 028916651; System requirements: World Wide Web browser and PDF reader.; Mode of access: World Wide Web.; Thesis (Ph.D.)--University of Central Florida, 2010.; Includes bibliographical references (p. 181-194).
Ph.D.
Doctorate
Optics

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14

Dorin, Bryce. "The fabrication of three-dimensional conductor-in-insulator composites using direct laser writing." Thesis, University of Manchester, 2017. https://www.research.manchester.ac.uk/portal/en/theses/the-fabrication-of-threedimensional-conductorininsulator-composites-using-direct-laser-writing(2b7d61f6-47da-4a3f-aeeb-783a0ccbbe3e).html.

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Direct laser write (DLW) processes are advancing the limits of fabrication technology in terms of reconfigurability, cost, and speed. Using this laser-based technique, three-dimensional (3D) structures have been demonstrated in a variety of materials. However, a DLW methodology had yet to be developed that can create conductive circuitry in 3D. In this project we demonstrate, for the first time, the fabrication of 3D conductor-in-insulator composites through a one-step DLW process. Two potential material systems for DLW circuits were investigated in this thesis. A stable silver-in-insulator hybrid was developed first, however this material failed to produce conductive 3D structures following laser irradiation. The second material system, polyimide (PI), exhibited promising conductivity increases of 16 orders of magnitude after DLW. Through rigorous process optimization, we were able to exploit non-linear absorption within the PI and produce conductive graphitic material in 3D. The DLW process and the resulting material modification were investigated thoroughly using a wide range of characterization and modelling techniques, including beam profiling, microscopy, Raman spectroscopy, thermal modelling, and energy dispersive X-ray spectroscopy. Through the development of 3D DLW conductor-in-insulator composites, we have created a novel method for electrically packaging encapsulated and randomly distributed devices down to the micro/nanoscale. Electrical contacts to both light emitting diodes and silver nanowires were demonstrated during this project. The process begins by scattering electrical devices across a film of PI, which are then encapsulated in high-clarity epoxy. Guided by a camera, it is possible to machine DLW graphitic wires ~20 Î1⁄4m in width through the encapsulate layer to form effective electrical contacts. This methodology provides an unique ability to package and contact electrical devices in a rapid and reconfigurable process.

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Alasadi, Alaa. "Development of laser direct writing for fabrication of micro/nano-scale magnetic structures." Thesis, University of Sheffield, 2018. http://etheses.whiterose.ac.uk/22820/.

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Traditional lithographic techniques used to fabricate a magnetic structure are often complex, time consuming, dependent on other techniques and expensive. Laser direct writing (LDW) can potentially overcome many of these drawbacks and may be a cheaper, faster and easier route to fabricating technique micro-/nano-magnetic structures. The main aim of this project is to fabricate magnetic structures through LDW. Two types of LDW were used to fabricate magnetic structures: subtractive LDW (LDW-) and laser-induced forward transfer (LIFT). LIFT was used to transfer permalloy (Ni81Fe19) using three laser systems. Numerous parameters were varied, including thin film thickness, scanning speed, pulse energy, distance between donor/acceptor and acceptor material. These attempts did not succeed in transferring the magnetic materials as a uniform shape. The differences of heat conductivity between the permalloy and acceptor substrate (glass and silicon), shock wave effects and the landing speed of material on the acceptor are the most possible reasons that the uniform structures and the magnetic properties were lost. LDW- was used to successfully pattern 90nm thick Permalloy into 1-D and 2-D microstructures. Magnetic wires with a range of widths, arrays of squares, rectangles with a range of aspect ratios and rhombic elements were patterned. These structures were fabricated using an 800-picosecond pulse laser and a 0.75 NA lens to give a 1.85µm diameter spot. Scan speeds were controlled to give 30% overlap between successive laser pulses and reduce the extent of width modulation in the final structures compared with lower levels of pulse overlap. Continuous magnetic wires that adjoined the rest of the film were fabricated with widths from 150 nm - 6.7µm and showed coercivity reducing across this range from 47 Oe to 10 Oe. Squares, rectangles and diamonds These elements demonstrated shape-sensitive magnetic behaviour with increasing the shape aspect ratio. Wires of different width were also fabricated by LDW- and their anisotropic magnetoresistance (AMR) determined to show a simple width-dependent magnetic field response, making them interesting as magnetic field sensors. This approach is extremely rapid and does not requires masks or chemical processing as part of the patterning procedure. The time required to patterned 1-D area of 4 x 0.18 mm was 85 s and the average fabrication time per element of 2-D structures was 4.7x10 4 s. The microstructures may be of use for AMR sensors or for biological applications, such as cell trapping.

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Do, Mai Trang. "Fabrication of submicrometer 3D structures by one-photon absorption direct laser writing and applications." Thesis, Cachan, Ecole normale supérieure, 2015. http://www.theses.fr/2015DENS0001/document.

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Ce travail porte sur l’étude d’une nouvelle technique de microscopie basée sur le phénomène d’absorption linéaire ultra-faible (LOPA) de matériaux photosensibles pour la fabrication de structures submicrométriques à deux et à trois dimensions (2D, 3D). Premièrement, nous avons étudié théoriquement la distribution de l'intensité lumineuse dans la région focale d’un objectif de microscope de grande ouverture numérique en fonction des différentes conditions de travail, telles que la propagation de la lumière dans un milieu absorbant avec variation d'indice de refraction. Nous avons démontré que lorsque l'on travaille avec un matériau quasi homogène ayant de très faible absorption à la longueur d’onde du faisceau d’excitation, le faisceau laser peut être focalisé en profondeur à l'intérieur du matériau, ce qui permet de manipuler optiquement des objets en 3D. Nous avons ensuite démontré expérimentalement l'utilisation de cette technique pour fabriquer des structures à la demande. Différentes structures 2D et 3D submicrométriques ont été crées en résine SU-8, en utilisant un laser continue de faible puissance à 532 nm. Ces résultats sont similaires à ceux obtenus par la méthode d’absorption à deux photons, mais le coût de fabrication a été énormément réduit. De plus, nous avons démontré qu'il est possible de fabriquer des structures photoniques à base de polymère contenant une seule nanoparticule (NP), en utilisant un procédé à deux étapes. En effet, nous avons d'abord déterminé avec précision la position d'une seule NP d’or, en utilisant une puissance d’excitation très faible, puis nous l'avons insérée dans une structure photonique par une puissance d’excitation plus élevée. Le couplage d'une NP d’or et d'une structure photonique à base de polymère a été ensuite étudié théoriquement et expérimentalement, montrant une amélioration importante de la collection des photons émis par la NP
This work deals with a novel microscopy technique based on the ultra-low one-photon absorption (LOPA) mechanism of photosensitive materials for fabrication of arbitrary two- and three-dimensional (2D, 3D) submicrometer structures. First, we theoretically investigated the intensity distribution at focusing region of a high numerical aperture objective lens as a function of various working conditions, such as propagation of light mismatched refractive index and/or absorbing media. We demonstrated that when working with refractive index mismatch-free and very low absorption conditions, the light could be focused deeply inside the material, allowing a 3D optical manipulation. We then demonstrated experimentally the use of this simple technique for fabrication of desired structures. Different 2D and 3D structures, with a feature as small as 150 nm, have been created in SU-8 photoresist by using a low power and continuous-wave laser emitting at 532 nm. Furthermore, we demonstrated that it is possible to fabricate a polymer-based photonic structure containing a single nanoparticle (NP), by using a double-step method. Indeed, the LOPA microscopy allowed us first to accurately determine the location of a single gold NP and then to embed it as desired into an arbitrary SU-8 photonic structure. The coupling of a gold NP and a polymer-based photonic structure was theoretically and experimentally investigated showing a six-fold photons collection enhancement as compared to that of a NP in unpatterned film

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Tong, Quang Cong. "Direct laser writing of polymeric and metallic nanostructures via optically induced local thermal effect." Thesis, Université Paris-Saclay (ComUE), 2016. http://www.theses.fr/2016SACLN073/document.

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Ce travail consiste à l’utilisation de la technique d'écriture directe par laser par absorption à un photon pour fabriquer des nanostructures polymères et métalliques en vue d’applications en photonique et en plasmonique. Il est démontré que la température du matériau est augmentée localement et temporellement grâce à une excitation locale d’un laser continu dont la longueur d’onde se situe dans la bande d’absorption du matériau. Un modèle théorique simple a été étudié pour expliquer l'effet photothermique local et temporel, qui est déterminé par le spot de focalisation du système d'écriture directe par laser. En utilisant une résine photosensible positive, il a été démontré que les structures photoniques 1D et 2D peuvent être réalisées avec une taille aussi petite que 57 nm et avec une périodicité aussi courte que 300 nm, ce qui sont beaucoup plus petites par rapport à la limite de diffraction du système optique utilisé. Les structures photoniques 3D ont également été fabriqués pour la première fois avec une photorésine positive, permettant d’envisager de nombreuses nouvelles applications. Les structures polymères fabriquées ont été démontrés très utiles pour obtenir des nanostructures plasmoniques par soit une combinaison de la méthode d’évaporation thermique d'un film d'or et le procédé lift-off, ou par une combinaison de la méthode de pulvérisation cathodique d'une couche d'or et la méthode de recuit thermique. Les nanostructures d'or fabriquées ont été caractérisées expérimentalement et leurs propriétés optiques ont été théoriquement confirmées par des calculs FDTD. En outre, il a été démontré que les nanostructures d'or, avec les tailles et formes contrôlables, peut être réalisées en une seule étape par la technique d’écriture directe par laser grâce à l'effet thermique optiquement induit. Certaines applications de ces nanostructures métalliques sont proposées et étudiés, par exemple, le capteur d'indice de réfraction, le stockage des données et l'impression couleur
This work focuses on the investigation of direct laser writing technique for fabrication of desired nanostructures on positive photoresist and metallic materials. The photothermal and photochemical processes deriving from one-photon absorption mechanism, which occurs when materials are excited by a green continuous-wave laser, enabled a scalable and practical approach for producing nanostructures on demand. A simple heat model was proposed to explain the local and temporal thermal effect, induced by a tiny focusing spot of the direct laser writing system. Using a positive photoresist, it was demonstrated that 1D and 2D photonic structures can be realized with a feature size as small as 57 nm and with a periodicity as short as 300 nm, which are much smaller than the diffraction limit of the used optical system. 3D photonic structures were also fabricated for the first time with a positive photoresist, paving the way to numerous applications. The fabricated polymeric structures have been demonstrated as excellent templates to obtain plasmonic nanostructures by a combination of thermal evaporation of gold film and lift-off process and/or by a combination of the sputtering of a thin gold layer and thermal annealing methods. Fabricated gold nanoarrays were experimentally characterized and their optical properties were theoretically confirmed by FDTD calculations. Furthermore, it was demonstrated that any gold nanostructure, with controllable size and shape, can be realized in one-step by direct laser writing technique thanks to the optically induced thermal effect. Some applications of these metallic nanostrucures are proposed, for instance, refractive index sensor, data storage, and color printing

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Onanuga, Temitope [Verfasser], Andreas [Akademischer Betreuer] Erdmann, and Bernhard [Gutachter] Schmauß. "Process modeling of two-photon and grayscale laser direct-write lithography / Temitope Onanuga ; Gutachter: Bernhard Schmauß ; Betreuer: Andreas Erdmann." Erlangen : Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), 2019. http://d-nb.info/1186380640/34.

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ZEYNALI, AMIRBAHADOR. "Two-photon assisted direct laser writing of proteinaceous microarchitectures containing plasmonic nanoparticles; characterization and optimization." Doctoral thesis, Università degli Studi di Milano-Bicocca, 2021. http://hdl.handle.net/10281/304319.

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Le nanoparticelle metalliche, grazie alle loro affascinanti proprietà ottiche ed elettrochimiche, attirano l'attenzione di diverse discipline scientifiche e di ricerca ingegneristica. Tra queste proprietà, l'effetto fototermico indotto dalle risonanze plasmoniche, è una caratteristica notevole ed esclusiva delle nanoparticelle di metalli nobili che, ad oggi, vengono già sfruttate per vari scopi, sia per ricerca che, soprattutto, per applicazioni biomediche. Il fenomeno della risonanza plasmonica superficiale, caratterizzato da bande ben definite, fornisce a queste nanoparticelle una notevole la flessibilità nella risposta ottica che si può vantaggiosamente trasferire a matrici polimeriche in cui queste vengano disperse. In particolare, la possibilità di indurre un aumento di temperatura altamente localizzato che può essere attivato tramite un dispositivo di stimolazione esterno come una sorgente di luce, renderebbe tali matrici strumenti preziosi nel campo dei trattamenti cellulari e, in generale, dell'ingegneria dei tessuti In questa tesi, la tecnica di scrittura (photo-cross-link) laser diretta (DLW), attivata da assorbimento a due fotoni, è stata impiegata per fabbricare micro-architetture con il diverso modulo elastico (da 80kPa a 800kPa) a partire da un inchiostro proteico composto da albumina di siero bovino (BSA), un foto-iniziatore (Rose Bengale o blu di metilene) e nanoparticelle d'oro a simmetria non sferica (GNP). Mostriamo qui che la presenza di queste ultime, se opportunamente schermate dall’interazione con il foto-iniziatore, fornisce alle microstrutture foto-polimerizzate la capacità di generare un aumento della temperatura locale mediante stimolazione nella regione spettrale del vicino infrarosso. L'efficienza fototermica misurata sotto l’effetto di radiazione laser focalizzata a 800 nm (in continua) su microstrutture caricate con una bassa concentrazione di atomi d'oro (1% w/w) ha raggiunto 12.2 pm 0.4 C/W, che costituisce un record di effetto fototermico indotto su una microstruttura a base proteica proteinica stampata tramite DLW. La funzionalità foto-termica derivante dalle GNP incorporate nelle microstrutture proteiche fabbricate riveste una notevole potenzialità nello studio delle risposte di sistemi viventi, come cellule e colture di batteri, al rilascio di calore altamente localizzato e controllato sia per quanto riguarda il tempo di irraggiamento che la dose rilasciata.
Metallic nanoparticles, due to their fascinating optical and electrochemical properties, attract the attention of different science and engineering research disciplines. Among these properties, the plasmonic photothermal effect is a notable and exclusive feature of noble-metal nanoparticles that, by today, are exploited through lots of research activities for various purposes, especially for biomedical applications. This optically-tunable phenomenon uniquely increases the flexibility of the optical response of host matrices, by allowing to induce highly localized temperature increases that can be triggered via simple external stimulation device like a light source. Such matrices can be valuable tools in the field of cell treatments and, in general, tissue engineering. In the present study, the two-photon-assisted direct laser writing (DLW) technique was employed to fabricate microarchitectures with the different elastic modulus (80kPa to 800kPa) from a proteinaceous ink composed of bovine serum albumin (BSA), rose Bengal (RB), or methylene blue (MB), and non-spherical symmetric gold nanoparticles (GNPs), with the ability to generate local temperature increase by stimulation in the near-infrared spectral region. The recorded photothermal efficiency measured using focused continuous wave (CW) laser irradiation at 800nm on microstructures loaded with GNPs at low gold atom concentration (1%w/w) reached 12.2 pm 0.4 C/W, that is a record photothermal effect induced from a printed proteinaceous feature. This photo-thermal functionality arising from the GNPs embedded within the fabricated proteinaceous microstructures can then be applied for studying responses of living systems like cells and bacteria cultures under an externally triggered highly localized heat release.

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Zoubir, Arnaud. "TOWARDS DIRECT WRITING OF 3-D PHOTONIC CIRCUITS USING ULTRAFAST LASERS." Master's thesis, University of Central Florida, 2004. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/3907.

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The advent of ultrafast lasers has enabled micromachining schemes that cannot be achieved by other current techniques. Laser direct writing has emerged as one of the possible routes for fabrication of optical waveguides in transparent materials. In this thesis, the advantages and limitations of this technique are explored. Two extended-cavity ultrafast lasers were built and characterized as the laser sources for this study, with improved performance over existing systems. Waveguides are fabricated in oxide glass, chalcogenide glass, and polymers, these being the three major classes of materials for the telecommunication industry. Standard waveguide metrology is performed on the fabricated waveguides, including refractive index profiling and mode analysis. Furthermore, a finite-difference beam propagation method for wave propagation in 3D-waveguides is proposed. The photo-structural modifications underlying the changes in the material optical properties after exposure are investigated. The highly nonlinear processes of the light/matter interaction during the writing process are described using a free electron model. UV/visible absorption spectroscopy, photoluminescence spectroscopy and Raman spectroscopy are used to assess the changes occurring at the atomic level. Finally, the impact of laser direct writing on nonlinear waveguide applications is discussed.
Ph.D.
Other
Optics and Photonics
Optics

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21

Borden, Bradley W. "A Study of Laser Direct Writing for All Polymer Single Mode Passive Optical Channel Waveguide Devices." Thesis, University of North Texas, 2008. https://digital.library.unt.edu/ark:/67531/metadc9805/.

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The objective of this research is to investigate the use of laser direct writing to micro-pattern low loss passive optical channel waveguide devices using a new hybrid organic/inorganic polymer. Review of literature shows previous methods of optical waveguide device patterning as well as application of other non-polymer materials. System setup and design of the waveguide components are discussed. Results show that laser direct writing of the hybrid polymer produce single mode interconnects with a loss of less 1dB/cm.

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Abou, Khalil Alain. "Direct laser writing of a new type of optical waveguides and components in silver containing glasses." Thesis, Bordeaux, 2018. http://www.theses.fr/2018BORD0290/document.

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L'inscription laser directe est un domaine de recherche en croissance depuis ces deux dernières décennies, fournissant un moyen efficace et robuste pour inscrire directement des structures en trois dimensions (3D) dans des matériaux transparents tels que des verres en utilisant des impulsions laser femtosecondes. Cette technique présente de nombreux avantages par rapport à la technique de lithographie, qui se limite à la structuration en deux dimensions (2D) et implique de nombreuses étapes de fabrication. Cela rend la technique d’inscription laser direct bien adaptée aux nouveaux procédés de fabrication. Généralement, l’inscription laser dans les verres induit des changements physiques tels qu'un changement permanent de l'indice de réfraction localisé. Ces modifications ont été classés en trois types distincts : (Type I, Type II et Type III). Dans ce travail, nous présentons un nouveau type de changement d'indice de réfraction, appelé type A qui est basé sur la création d’agrégats d'argent photo-induit. En effet, dans des verres dans lesquels sont incorporés des ions argent Ag+, lors de leurs synthèses, l’inscription laser directe induit la création d’agrégats d’argent fluorescents Agmx+ au voisinage du voxel d’interaction. Ces agrégats modifient localement les propriétés optiques comme : la fluorescence, la non-linéarité et la réponse plasmonique du verre. Ainsi, différents guides d'ondes, un séparateur de faisceau 50-50, ainsi que des coupleurs optiques ont été inscrits en se basant sur ce nouveau Type A et complétement caractérisés. D'autre part, une étude comparative entre les deux types de guides d'ondes (type A et type I) est présentée, tout en montrant qu’en ajustant les paramètres laser, il est possible de déclencher soit le Type I soit le Type A. Enfin, en se basant sur des guides d’ondes de type A inscrits proche de la surface du verre, un capteur d'indice de réfraction hautement sensible a été inscrit dans une lame de verre de 1 cm de long. Ce capteur miniaturisé peut présenter deux fenêtres de détection d’indice, ce qui constitue une première mondiale. Les propriétés des guides d'ondes inscrits dans ces verres massifs ont été transposées à des fibres en forme de ruban, du même matériau contenant de l'argent. Les résultats obtenus dans ce travail de thèse ouvrent la voie à la fabrication de circuits intégrés en 3D et de capteurs à fibre basés sur des propriétés optiques originales inaccessibles avec des guides d’onde de Type I standard
Direct Laser Writing (DLW) has been an exponentially growing research field during the last two decades, by providing an efficient and robust way to directly address three dimensional (3D) structures in transparent materials such as glasses using femtosecond laser pulses. It exhibits many advantages over lithography technique which is mostly limited to two dimensional (2D) structuring and involves many fabrication steps. This competitive aspect makes the DLW technique suitable for future technological transfer to advanced industrial manufacturing. Generally, DLW in glasses induces physical changes such as permanent local refractive index modifications that have been classified under three distinct types: (Type I, Type II & Type III). In silver containing glasses with embedded silver ions Ag+, DLW induces the creation of fluorescent silver clusters Agmx+ at the vicinity of the interaction voxel. In this work, we present a new type of refractive index change, called type A that is based on the creation of the photo-induced silver clusters allowing the creation of new linear and nonlinear optical waveguides in silver containing glasses. Various waveguides, a 50-50 Y beam splitter, as well as optical couplers, were written based on type A modification inside bulk glasses and further characterized. On the other hand, a comparison study between type A and type I waveguides is presented, showing that finely tuning the laser parameters allows the creation of either type A or type I modification inside silver containing glasses. Finally, based on type A near-surface waveguides, a highly sensitive refractive index sensor is created in a 1 cm glass chip, which could exhibit a pioneer demonstration of double sensing refractive ranges. The waveguiding properties observed and reported in the bulk of such silver containing glasses were transposed to ribbon shaped fibers of the same material. Those results pave the way towards the fabrication of 3D integrated circuits and fiber sensors with original fluorescent, nonlinear and plasmonic properties that are not accessible using the standard type I modification

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Tal, Amir. "THREE-DIMENSIONAL MICRON-SCALE METAL PHOTONIC CRYSTALS VIA MULTI-PHOTON DIRECT LASER WRITING AND ELECTROLESS METAL DEPOSITION." Master's thesis, University of Central Florida, 2007. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/3889.

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Three-dimensional (3D) metal photonic crystals (MPCs) can exhibit interesting electromagnetic properties such as ultra-wide photonic or "plasmonic" band gaps, selectively tailored thermal emission, extrinsically modified absorption, and negative refractive index. Yet, optical-wavelength 3D MPCs remain relatively unexplored due to the challenges posed by their fabrication. This work explores the use of multi-photon direct laser writing (DLW) coupled with electroless metallization as a means for preparing MPCs. Multi-photon DLW was used to prepare polymeric photonic crystal (PC) templates having a targeted micron-scale structure and form. MPCs were then created by metallizing the polymeric PCs via wet-chemical electroless deposition. The electromagnetic properties of the polymeric PCs and the metallized structures were characterized using Fourier transform infrared spectroscopy. It is shown that metallization transforms the optical properties of the structures from those of conventional 3D dielectric PCs to those consistent with 3D MPCs that exhibit ultra-wide photonic band gaps. These data demonstrate that multi-photon DLW followed by electroless deposition provides a viable and highly flexible route to MPCs, opening a new path to metal photonic materials and devices.
M.S.
Optics and Photonics
Optics and Photonics
Optics MS

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Williams, Jr Henry. "Photophysical and photochemical factors affecting multi-photon direct laser writing using the cross-linkable epoxide SU-8." Doctoral diss., University of Central Florida, 2013. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/6382.

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For the past decade, the epoxy based photoresist SU-8 has been used commercially and in the lab for fabricating micro- and nano-structures. Investigators have studied how processing parameters such as pre- and post-exposure bake temperatures affect the resolution and quality of SU-8 structures patterned using ultraviolet or x-ray lithography. Despite the advances in understanding the phenomena, not all of them have been explored, especially those that are specific to multi-photon direct laser writing (mpDLW). Unlike conventional exposure techniques, mpDLW is an inherently three-dimensional (3D) process that is activated by nonlinear absorption of light. This dissertation reports how several key processing parameters affect mpDLW using SU-8 including pre-exposure bake duration, focal depth, incident laser power, focal-point scan speed, and excitation wavelength. An examination of solvent content of films at various stages in the mpDLW by 1H-NMR shows that even moderate solvent content (over 1 wt-%) affects film viscosity and photoacid diffusion lengths, and can greatly affect the overall fidelity of small features. A study of micro-fabricated feature size versus writing depth in the material shows that even slight refractive index mismatch between SU-8 and the medium between it and the focusing objective introduces spherical aberration that distorts the focus, causing feature size to decrease or even increase in size with writing depth, depending on the average exposure power used. Proper adjustment of the average exposure power was demonstrated as a means to fabricate more uniform features with writing depth. Third, when varying the power and scan speed, it was observed that the feature-size scales with these two parameters in a manner that is consistent with a three-photon absorption mechanism at an excitation wavelength of 800 nm. When an excitation wavelength of 725 nm is used, the feature-size scaling becomes consistent with that of two photon absorption. This shows that the photoinitiators in the SU-8 can be activated by either two- or three-photon absorption over this wavelength range. Using an irradiance of ~2 TW cm-2 and elongated femtosecond pulses resulted in an observed fourth order power dependence. This observation is in agreement with the literature and suggests that the effective absorptive nonlinearity is also sensitive to pulse duration. These findings will be useful for creating accurate models of the process of mpDLW in SU-8. These models could be used to optimize the processing parameters and develop new processing methods and materials for high-resolution fabrication of robust 3D microstructures. Some of the findings were used to develop a method for fabricating functional microlenses on the tip of optical fibers. This approach opens a new route to functional integrated photonic devices.
Ph.D.
Doctorate
Chemistry
Sciences
Chemistry

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Deubel, Markus. "Three-dimensional photonic crystals via direct laser writing : fabrication and characterization = Dreidimensionale photonische Kristalle mittels direkten Laserschreibens /." Aachen : Shaker, 2006. http://swbplus.bsz-bw.de/bsz252812697abs.htm.

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Borden, Bradley W. Wang Shuping. "A study of the laser direct writing for all polymer single mode passive optical channel waveguide devices." [Denton, Tex.] : University of North Texas, 2008. http://digital.library.unt.edu/permalink/meta-dc-9805.

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Guo, Qingchuan [Verfasser], Andreas [Akademischer Betreuer] Ostendorf, and Evgeny L. [Akademischer Betreuer] Gurevich. "Synthesis and fabrication of functional microstructures by laser direct writing techniques / Qingchuan Guo. Gutachter: Andreas Ostendorf ; Evgeny L. Gurevich." Bochum : Ruhr-Universität Bochum, 2016. http://d-nb.info/108242529X/34.

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Müller, Jonathan Benedikt [Verfasser], and M. [Akademischer Betreuer] Wegener. "Exploring the Mechanisms of Three-Dimensional Direct Laser Writing by Multi-Photon Polymerization / Jonathan Benedikt Müller. Betreuer: M. Wegener." Karlsruhe : KIT-Bibliothek, 2015. http://d-nb.info/1072464608/34.

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Kallur, Ajay. "Micro-fabrication of a Mach-Zehnder interferometer combining laser direct writing and fountain pen micropatterning for chemical/biological sensing applications." Thesis, University of North Texas, 2009. https://digital.library.unt.edu/ark:/67531/metadc10989/.

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This research lays the foundation of a highly simplified maskless micro-fabrication technique which involves incorporation of laser direct writing technique combined with fountain pen based micro-patterning method to fabricate polymer-based Mach-Zehnder interferometer sensor arrays' prototype for chemical/biological sensing applications. The research provides methodology that focuses on maskless technology, allowing the definition and modification of geometric patterns through the programming of computer software, in contrast to the conventional mask-based photolithographic approach, in which a photomask must be produced before the device is fabricated. The finished waveguide sensors are evaluated on the basis of their performance as general interferometers. The waveguide developed using the fountain pen-based micro-patterning system is compared with the waveguide developed using the current technique of spin coating method for patterning of upper cladding of the waveguide. The resulting output power profile of the waveguides is generated to confirm their functionality as general interferometers. The results obtained are used to confirm the functionality of the simplified micro-fabrication technique for fabricating integrated optical polymer-based sensors and sensor arrays for chemical/biological sensing applications.

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Kallur, Ajay Wang Shuping. "Micro-fabrication of a Mach-Zehnder interferometer combining laser direct writing and fountain pen micropatterning for chemical/biological sensing applications." [Denton, Tex.] : University of North Texas, 2009. http://digital.library.unt.edu/permalink/meta-dc-10989.

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Nguyen, Ho Hoai Duc [Verfasser], and C. [Akademischer Betreuer] Koos. "Novel Photostructurable Polymer for On-Board Optical Interconnects Enabled by Femtosecond Direct Laser Writing / Ho Hoai Duc Nguyen ; Betreuer: C. Koos." Karlsruhe : KIT-Bibliothek, 2021. http://d-nb.info/1239180616/34.

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Šimkevičius, Artūras. "Kampinių skalių originalų formavimo stendo sukūrimas ir tyrimas." Master's thesis, Lithuanian Academic Libraries Network (LABT), 2014. http://vddb.library.lt/obj/LT-eLABa-0001:E.02~2014~D_20140616_093419-67508.

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Baigiamojo darbo tikslas – sukurti precizinių kampinių skalių formavimo įrenginį. Darbe yra išanalizuoti kampinių skalių formavimo metodai ir jų realizacijos sistemos, išskirti kampinių skalių formavimo neapibrėžties sandai, suformuoti darbo tikslai, užduotys. Yra išanalizuotos ir ištirtos optimalios įrenginio komponentės. Pasiūlyta įrenginio schema. Nustatyti rastrinių skalių originalų formavimo neapibrėžties atsiradimo dėsningumai. Išskirtos trys pagrindinės paklaidų grupės: judesio, temperatūrinės, kalibravimo. Darbe pateikiama tyrimo metodika – tyrimų eiga, tyriami mazgai ir sistemos, rezultatų apdorojimo metodika. Tyrimo rezultatai pateikti grafiškai, apdoroti statistiniais metodais, apibendrinantys rezultatai apkroksimuoti parametrinėmis funkcijomis. Darbą sudaro 9 dalys: įvadas, problemos analizė ir užduoties formulavimas, precizinių suklių tyrimai, kampo matavimo sistemos kalibravimo tikslumo tyrimas, temperatūrinių gradientų ir jų poveikio tyrimas, linijinių poslinkių matavimų tyrimai, kampinių skalių originalų konstrukcijos parinkimas ir pagrindimas, išvados, literatūros sąrašas. Darbo apimtis – 83 p. teksto be priedų, 55 iliustracijų, 35 bibliografinių šaltinių. Atskirai pridedami priedai.
Final work is dedicated for development of device for precision angular glass scales originals forming. Methods of angular scales forming and their realization have been analyzed. Distinguished angular scales forming elements of uncertainty. Work objectives and tasks have been formed. There are analyzed and researched the optimum device composition. Device scheme is proposed. Angular raster scales forming uncertainty occurrence of patterns determined. Identified three main error groups: motion, temperature and calibration. The work presents research methodology – research process, research components and systems, research data processing techniques. The results are presented graphically and processed by statistical methods, summarized results approximated by parametrical functions. Thesis consists of 9 chapters: introduction, problem analysis and formulation of the task, precision spindle research, angle measuring system accuracy research, temperature gradients and their impact research, linear displacement measurement study, angular scales original forming stand design selection and justification, conclusions, references. Thesis consist of: 83 p. text without appendixes, 55 pictures, 35 bibliographical entries. Appendixes included.

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Liang, Shijie. "Photonic structures fabricated in polymer materials using femtosecond laser irradiation." Thesis, University of Manchester, 2012. https://www.research.manchester.ac.uk/portal/en/theses/photonic-structures-fabricated-in-polymer-materials-using-femtosecond-laser-irradiation(cf1a7c56-9d66-44e4-9b18-0641445a2661).html.

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Sub-surface modification using a frequency doubled Ti: Sapphire femtosecond (fs) laser at 1kHz repetition rate, producing 100-fs pulse duration at 400nm, is studied in order to fabricate optical components within non-photosensitised polymethyl methacrylate (PMMA). This thesis explores the feasibility of producing three-dimensional optical devices in bulk polymers and polymer optical fibre (POF) using fs laser direct-writing techniques. For effective and optimal structuring, the laser writing parameters and focusing conditions, such as focusing depth, translation speed, and accumulated fluence are investigated by means of photo-modification thresholds; structural changes in dimensions and morphologies; and the magnitude of the refractive index modulation. The highest refractive index change is 3.2x10^(-3) achieved by using a dry (non-immersion) 0.45-NA objective for a single laser scan. Variations in damage threshold with focusing depths are attributed to a combination of material absorption or surface scattering of light due to contamination or surface imperfections, as well as oxygen diffusion and spherical aberration. Distortion of the laser-induced feature size and shape due to spherical aberrations is controlled and compensated by adjusting the laser power near the damage threshold. Permanent refractive index structures with cross-sectional dimensions of 2μm by 0.9μm and 3μm by 1.4μm are demonstrated at depths of 300μm and 500μm below the surface, resulting in the axial/ lateral ratio of 2.2 and 2.1, respectively. A novel phenomenon relevant to effects of translation speed on the fs laser modification is observed for the first time. As translation speeds reduce from 1.2 to 0.6mm/s, the optical damage threshold power decreases by 6μW, whilst other writing conditions remain constant. However, the damage threshold increases by 74μW with decreasing speeds from 0.6 to 0.35mm/s. This significant increase in threshold power enables inscription of refractive index gratings <5μm below the surface, because irradiation on the surface or near the surface initiates ablation rather than refractive index changes, and this forms a limit for writing useful structures. Compensating for this limit by using appropriate writing parameters highlights the potential of fabricating three-dimensional integrated optical circuits in thin (100μm) polymer substrates. Finally, highly localised fabrication of long period gratings into step-index single mode polymer fibres is demonstrated by removing distortion effects due to the curved surface. The distortion is compensated by sandwiching the fibre with two flat PMMA sheets, between which index-matching oil (n=1.5) is injected. This arrangement enables precise laser micro-structuring with flat interfaces and continuous inner material. The first demonstration of a 250-μm-period fibre grating, resulting in attenuation bands in the visible spectral region at 613, 633, 728, 816, 853, 877 and 900nm, is presented.

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Kirchner, Johannes [Verfasser], Eberhard [Akademischer Betreuer] Manske, Tino [Gutachter] Hausotte, and Peter [Gutachter] Lehmann. "Grundlegende Entwicklungen und Untersuchungen zur Mikro- und Nanostrukturierung durch Direct Laser Writing in Nanopositionier- und Nanomessmaschinen / Johannes Kirchner ; Gutachter: Tino Hausotte, Peter Lehmann ; Betreuer: Eberhard Manske." Ilmenau : TU Ilmenau, 2020. http://d-nb.info/1216951055/34.

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Ten, Jyi Sheuan. "High speed mask-less laser-controlled precision micro-additive manufacture." Thesis, University of Cambridge, 2019. https://www.repository.cam.ac.uk/handle/1810/285409.

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A rapid, mask-less deposition technique for writing metal tracks has been developed. The technique was based on laser-induced chemical vapour deposition. The novelty in the technique was the usage of pulsed ultrafast lasers instead of continuous wave lasers in pyrolytic dissociation of the chemical precursor. The motivation of the study was that (1) ultrafast laser pulses have smaller heat affected zones thus the deposition resolution would be higher, (2) the ultrashort pulses are absorbed in most materials (including those transparent to the continuous wave light at the same wavelength) thus the deposition would be compatible with a large range of materials, and (3) the development of higher frequency repetition rate ultrafast lasers would enable higher deposition rates. A deposition system was set-up for the study to investigate the ultrafast laser deposition of tungsten from tungsten hexacarbonyl chemical vapour precursors. A 405 nm laser diode was used for continuous wave deposition experiments that were optimized to achieve the lowest track resistivity. These results were used for comparison with the ultrafast laser track deposition. The usage of the 405 nm laser diode was itself novel and beneficial due to the low capital and running cost, high wall plug efficiency, high device lifetime, and shallower optical penetration depth in silicon substrates compared to green argon ion lasers which were commonly used by other investigators. The lowest as-deposited track resistivity achieved in the continuous wave laser experiments on silicon dioxide coated silicon was 93±27 µΩ cm (16.6 times bulk tungsten resistivity). This deposition was done with a laser output power of 350 mW, scan speed of 10 µm/s, deposition pressure of 0.5 mBar, substrate temperature of 100 °C and laser spot size of approximately 7 µm. The laser power, scan speed, deposition pressure and substrate temperature were all optimized in this study. By annealing the deposited track with hydrogen at 650 °C for 30 mins, removal of the deposition outside the laser spot was achieved and the overall track resistivity dropped to 66±7 µΩ cm (11.7 times bulk tungsten resistivity). For ultrafast laser deposition of tungsten, spot dwell experiments showed that a thin film of tungsten was first deposited followed by quasi-periodic structures perpendicular to the linear polarization of the laser beam. The wavelength of the periodic structures was approximately half the laser wavelength (λ/2) and was thought to be formed due to interference between the incident laser and scattered surface waves similar to that in laser-induced surface periodic structures. Deposition of the quasi-periodic structures was possible on stainless steel, silicon dioxide coated silicon wafers, borosilicate glass and polyimide films. The thin-films were deposited when the laser was scanned at higher laser speeds such that the number of pulses per spot was lower (η≤11,000) and using a larger focal spot diameter of 33 µm. The lowest track resistivity for the thin-film tracks on silicon dioxide coated silicon wafers was 37±4 µΩ cm (6.7 times bulk tungsten resistivity). This value was achieved without post-deposition annealing and was lower than the annealed track deposited using the continuous wave laser. The ultrafast tungsten thin-film direct write technique was tested for writing metal contacts to single layer graphene on silicon dioxide coated silicon substrates. Without the precursor, the exposure of the graphene to the laser at the deposition parameters damaged the graphene without removing it. This was evidenced by the increase in the Raman D peak of the exposed graphene compared to pristine. The damage threshold was estimated to be 53±7 mJ/cm2 for a scanning speed of 500 µm/s. The deposition threshold of thin-film tungsten on graphene at that speed was lower at 38±8 mJ/cm2. However, no graphene was found when the deposited thin-film tungsten was dissolved in 30 wt% H2O2 that was tested to have no effect on the graphene for the dissolution time of one hour. The graphene likely reacted with the deposited tungsten to form tungsten carbide which was reported to dissolve in H2O2. Tungsten carbide was also found on the tungsten tracks deposited on reduced graphene oxide samples. The contact resistance between tungsten and graphene was measured by both transfer length and four-point probe method with an average value of 4.3±0.4 kΩ µm. This value was higher than reported values using noble metals such as palladium (2.8±0.4 kΩ µm), but lower than reported values using other metals that creates carbides such as nickel (9.3±1.0 kΩ µm). This study opened many potential paths for future work. The main issue to address in the tungsten ultrafast deposition was the deposition outside the laser spot. This prevented uniform deposition in successive tracks close to one another. The ultrafast deposition technique also needs verification using other precursors to understand the precursor requirements for this process. An interesting future study would be a combination with a sulphur source for the direct write of tungsten disulphide, a transition metal dichalcogenide that has a two-dimensional structure similar to graphene. This material has a bandgap and is sought after for applications in high-end electronics, spintronics, optoelectronics, energy harvesting, flexible electronics, DNA sequencing and personalized medicine. Initial tests using sulphur micro-flakes on silicon and stainless-steel substrates exposed to the tungsten precursor and ultrafast laser pulses produced multilayer tungsten disulphide as verified in Raman measurements.

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Gernhardt, Marvin. "Multi-material microstructures with novel stimuli-responsive properties." Thesis, Queensland University of Technology, 2021. https://eprints.qut.edu.au/210195/1/Marvin_Gernhardt_Thesis.pdf.

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This thesis presents the development of two novel materials that undergo drastic changes when exposed to a certain trigger. One of them becomes harder and stiffer when exposed to visible light of a certain wavelength and one of them degrades when exposed to a certain enzyme. The properties of the materials were investigated thoroughly. The advanced 3D printing technique direct laser writing was used to fabricate microscopic structures from both materials. Such microstructures possessing highly adaptable properties could be used as scaffold materials for cells in order to study their development as a response to the triggered changes.

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Choi, Ji Yeon. "Ecriture par Laser de fonctionnalités optiques : éléments diffractifs et ONL." Phd thesis, Université Sciences et Technologies - Bordeaux I, 2010. http://tel.archives-ouvertes.fr/tel-00583861.

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A la suite de la première démonstration de l'écriture de guide d'onde au sein de verres en 1996 par laser femtoseconde, l'écriture direct par Laser Femtoseconde (Femtoseconde Direct Laser Writing - FLDW) est apparu comme une technique souple pour la fabrication de structure photonique en trois dimensions au sein de matériaux pour l'optique. La thèse a porté sur l'inscription par laser femtoseconde de fonctionnalités optiques au sein de verres. Des éléments diffractifs par modification de l'indice de réfraction et des structures présentant des propriétés de luminescence ou d'optique non linéaire d'ordre deux ont pu être obtenus au sein de matériaux vitreux et étudiés.

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Telitel, Siham. "Photopolymérisation radicalaire contrôlée pour la micro-nanostructuration de polymères fonctionnels." Thesis, Mulhouse, 2015. http://www.theses.fr/2015MULH8372/document.

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La fabrication de surfaces polymères complexes avec des chimies et des topographies contrôlées à l’échelle micro et nanométrique est en pleine expansion en raison de la large gamme d'applications. Une nouvelle méthode prometteuse consiste à utiliser la photopolymérisation radicalaire contrôlée par les nitroxydes (NMP2) qui exploite une alcoxyamine photosensible (AA).Pour démontrer le potentiel de fabrication de surfaces de polymères complexes, un film de polymère a d'abord été formé en irradiant avec une formulation contenant un mélange de monomère acrylique et l’alcoxyamine. Ensuite, le dépôt d'un second monomère acrylique sur ce film durci peut redémarrer une nouvelle réaction de photopolymérisation du fait de la présence d'alcoxyamines à la surface. Les radicaux peuvent être réactivés par exposition aux lampes UV et permettent de commencer un nouveau procédé de polymérisation. Une autre alternative est d'utiliser l’écriture directe par laser pour produire des structures en 2D ou 2.5D de polymère, en déplaçant le faisceau laser sur la surface de l'échantillon.Un soin particulier a été axé sur l'impact de paramètres photoniques et chimiques sur le processus de repolymérisation. Les mécanismes moléculaires qui régissent la repolymérisation pourraient être déduits de cette étude.Certaines applications montrent le potentiel de l'alcoxyamine pour générer des surfaces hydrophiles / hydrophobes ou fluorescentes pour des applications avancées
The fabrication of complex polymer surfaces with controled chemistry and topography at the micro and nanoscale has drawn a huge attention during the last years due to the wide range of applications. A promising new method consists in using the nitroxide mediated photopolymerization (NMP2). this method exploits a photosensitive alkoxyamine (AA) that creates latent reactive radical species.To demonstrate the potential for fabrication of complex polymer surfaces, a polymer film was first formed by irradiating with a formulation containing a mixture of acrylic monomer and alkoxyamine. Then, depositing a second acrylic monomer over this cured film can reboot a new photopolymerization reaction due to the presence of alkoxyamines at the surface. The radicals can be reactivated by exposure to UV and start a new polymerization process. Another alternative is to use UV-laser direct writing to produce 2D or 2.5D polymer structure by displacing the laser beam at the surface of the sample.A special care was focused on investigating the impact of photonic and chemical parameters on the extend of the repolymerization process. The molecular mechanisms governing the repolymerization could be deduced from this study.Some applications are provided showing the potential of the alkoxyamine for generating hydrophilic/hydrophobic or fluorescent surfaces for advanced applications

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Souquet, Agnès. "Etude des processus physiques mis en jeu lors de la microimpression d'éléments biologiques assistée par laser." Thesis, Bordeaux 1, 2011. http://www.theses.fr/2011BOR14232/document.

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Parallèlement à l’impression jet d’encre et au bioplotting, l’impression d'éléments biologiques assistée par laser (Laser Assisted Bioprinting : LAB) qui utilise le transfert vers l’avant induit par laser (Laser Induced Forward Transfer : LIFT) a émergé comme une méthode alternative dans l’assemblage et la micro–structuration de biomatériaux et de cellules. Le LAB est une technique d’écriture directe qui offre la possibilité d’imprimer des motifs avec une haute résolution spatiale à partir d'une large gamme de matériaux solides ou liquides, tels que des diélectriques, des biomolécules et des cellules vivantes en solution.Dans nos travaux de recherche, nous avons considéré une approche expérimentale et numérique pour étudier les mécanismes physiques mis en jeu lors de la microimpression d’éléments biologiques assistée par laser. Dans un premier temps nous avons défini les paramètres rhéologiques des bioencres et les conditions de transfert (composition, épaisseur et viscosité de la bioencre et énergie laser). Puis nous avons mené une analyse statistique du volume des gouttelettes déposées pour quatre viscosités de bioencre, cinq épaisseurs de bioencre et cinq énergies laser. Ensuite nous avons conçu et mis en place un système d’imagerie résolue en temps pour étudier les effets de la viscosité sur la dynamique de l’éjection. Nous avons ainsi différencié trois régimes d'éjection en fonction de l'énergie laser déposée dans la couche absorbante, de la viscosité et de l'épaisseur de la bioencre. Parallèlement, un modèle numérique a été mis en place pour comprendre et prédire la dynamique de l’éjection en fonction de paramètres multiples : choix et épaisseur de la couche absorbante, épaisseur de la couche de bioencre, énergie laser déposée. Enfin, au regard de ces études, nous proposons un mécanisme d'éjection des microgouttelettes intervenant au cours du procédé de microimpression assistée par laser
Over this decade, cell printing strategy has emerged as one of the promising approaches to organize cells in two and three dimensional engineered tissues. In parallel with ink-jet printing and bioplotting, Laser Assisted Bioprinting (LAB) using Laser-Induced Forward Transfer (LIFT) has emerged as an alternative method in the assembly and micropatterning of biomaterials and cells. LAB is a laser direct-write technique that offers the possibility of printing micropatterns with high spatial resolution from a wide range of solid or liquid materials, such as dielectrics, biomolecules and living cells in solution. In our research works, we considered an experimental and numerical approach to study the physical mechanisms involved in the biological elements microprinting laser assisted.First we defined the rheological parameters of bioinks and the transfer conditions (composition, thickness and viscosity of the bioink and laser energy). Then we led a statistical analysis of the volume of the transfer droplets for four viscosities of bioink, five thicknesses of bioink and five laser energies. Then we designed and implemented a system for time resolved imaging to study the effects of viscosity on the dynamics of the ejection. Thus we have differentiated three ejection regimes in function of the laser energy released in the absorbing layer, the visocsity and the thickness of the bioink. In parallel, a numerical model was developed to understand and predict the dynamics of the ejection parameters according to multiple choice and thickness of the absorbing layer, thickness of the layer bioencre, energy deposited. Finally, with regard to these studies, we propose a mechanism for ejecting droplets involved in the process of laser-assisted microprinting

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Salas, Oriana Ines Avila. "Processamento de poli(p-fenilenovinileno) (PPV) com pulsos laser de femtossegundos: fabricação de microestruturas óptica e eletricamente ativas." Universidade de São Paulo, 2018. http://www.teses.usp.br/teses/disponiveis/76/76132/tde-24092018-153428/.

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O poli (p-fenilenevinileno), ou PPV, é um polímero de grande relevância tecnológica devido a suas propriedades eletroluminescentes, que têm sido exploradas em diodos emissores de luz orgânicos, displays flexíveis e outros dispositivos optoeletrônicos. Embora o PPV seja um material de importância para muitas aplicações, a sua síntese na nano/microescala não pode ser obtida através do método padrão, o qual utiliza o aquecimento de um polímero precursor poli (cloreto de xileno tetrahidrotiofenio) (PTHT). Este trabalho mostra como a microestruturação com pulsos de femtosegundo pode ser empregada para a síntese de PPV em regiões pré-determinadas, empregando três diferentes abordagens, permitindo uma nova metodologia para a fabricação precisa de microcircuitos poliméricos complexos, (i) na primeira abordagem, o processo de conversão é obtido pela irradiação de filmes de PTHT com pulsos laser ultracurtos em regiões previamente determinadas, o que leva ao controle espacial da formação de PPV em microescala, (ii) na segunda abordagem, microestruturas tridimensionais dopadas com PTHT foram fotopolimerizadas por absorção de dois fótons. A conversão de PTHT para PPV nestas microestruturas dopadas foi obtida após um tratamento térmico, (iii) na terceira abordagem, a transferência direta induzida por laser (LIFT) com pulsos de femtossegundos permite a deposição controlada de PPV com alta resolução espacial, fornecendo micropadrões 2D, preservando sua estrutura e propriedades ópticas. As estruturas foram caracterizadas por microscopia eletrônica de varredura, microscopia óptica de transmissão, microscopia de fluorescência e microscopia confocal de fluorescência. Suas propriedades ópticas foram analisadas através de sistemas de micro-fotoluminescência e micro-absorção implementadas em um microscópio invertido. Medidas de espectroscopia Raman, microscopia de força atômica e medidas elétricas também foram realizadas. Este trabalho mostra como a microestruturação com laser de fs pode ser explorada para a síntese de PPV em regiões pré-determinadas para fabricar uma variedade de microdispositivos, abrindo novos caminhos na optoeletrônica baseada em polímeros.
Poly(p-phenylenevinylene), or PPV, is a polymer of great technological relevance due to its electroluminescent properties, which have been exploited in organic light emitting diodes, flexible displays and other optoelectronic devices. Although PPV is a material of foremost importance for many applications, its synthesis at the nano/micro scale cannot be achieved through the standard method that uses heating of a precursor polymer poly(xylene tetrahydrothiophenium chloride)(PTHT). This work demonstrates the use of direct laser writing with femtosecond pulses to obtain the synthesis of PPV in pre-determined regions, by applying three different approaches, allowing the precise fabrication of complex polymeric microcircuits, (i) in the first approach the conversion process is achieved by irradiating PTHT films with ultra-short laser pulses in previously determined regions, which leads to the spatial control of PPV formation at microscale, (ii) in the second approach, three-dimensional microstructures doped with PTHT were photopolymerized by two photons absorption. The conversion of PTHT to PPV in these doped microstructures was obtained by a subsequent thermal treatment, (iii) in the third approach, laser-induced forward transfer (LIFT) with femtosecond pulses enables the controlled deposition of PPV with high spatial resolution, providing 2D micropatterns, while preserving its structure and optical properties. The structures were characterized by scanning electron, fluorescence, transmission and confocal fluorescence microscopies. Their optical properties were analyzed by micro-photoluminescence and micro-absorption setups assembled on an inverted microscope. Raman spectroscopy, electrical measurements and atomic force microscopy were also performed. This thesis shows the use of fs-laser writing methods for the synthesis of PPV in pre-determined regions, to fabricate a variety of microdevices, thus opening new avenues in polymer-based optoelectronics.

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Alves, Jessica. "Advanced photochemical reaction systems for molecular design." Thesis, Queensland University of Technology, 2022. https://eprints.qut.edu.au/227734/1/Jessica_Alves_Thesis.pdf.

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Direct laser writing is a technique for printing complex 3D structures with high resolution by irradiating a photoresist in a two-photon process. Improved resolution and dynamic material properties of the printed structures is critical. Herein, advanced photochemical systems were investigated, potentially enabling dual-wavelength direct laser writing. Such systems consisting of organic photoswitches enable the formation of a single product only when irradiated with two wavelengths. A well-known class of photoswitches was investigated for this purpose and its chemistry was carefully explored. Further, photocatalysis combined with a photoswitch was identified as a possible strategy for the two-colour activated photoresist development.

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Chia, Gomez Laura Piedad. "Elaboration et caractérisation de matériaux fonctionnels pour la stereolithographie biphotonique." Thesis, Mulhouse, 2017. http://www.theses.fr/2017MULH9153.

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La stéréolithographie biphotonique (TPS) est une technique de microfabrication 3D basée sur la polymérisation par absorption biphotonique qui permet d’obtenir en une seule étape des structures 3D complexes avec des détails sub-100nm. Aujourd’hui, en raison des conditions spécifiques de fabrication liées à la TPS (fort flux, confinement spatial de la photoréaction,…), un des enjeux concerne le développement de matériaux fonctionnels compatibles avec ce procédé. Dans ce contexte, l’objectif de cette thèse a été de développer de nouveaux matériaux fonctionnels à base de polymères à empreintes moléculaires (MIP) pour élaborer des capteurs chimiques. Une première partie de ce travail a consisté à mettre en place différentes méthodes dédiées à la caractérisation des propriétés géométriques, chimiques et mécaniques des matériaux élaborés par TPS. Par exemple, la vibrométrie laser a été utilisée pour la première fois afin de sonder de façon non-invasive les propriétés mécaniques de microstructures réalisées par TPS. Dans un second temps, ce travail a été mis à profit pour étudier l’impact du processus de fabrication (i.e. conditions photoniques) ainsi que des paramètres physico-chimiques affectant la photoréaction (i.e. inhibition par oxygène et nature du monomère) sur les propriétés finales des matériaux. Enfin, en s’appuyant sur les résultats obtenus, des microcapteurs chimiques à base de MIP, à lecture optique ou mécanique, ont été fabriqués. Leurs propriétés de reconnaissance moléculaire, ainsi que leurs sélectivités ont été démontrées pour une molécule cible modèle (D-L-Phe)
The two-photon stereolithography (TPS) technique is a micro-nanofabrication method based on photopolymerization by two-photon absorption that allows in a single manufacturing step to obtain complex 3D structures with high-resolution details (sub-100nm). Due to the specific conditions of TPS process (intense photon flux, spatial confinement of the photoreaction…) one of the main concerns today is the development of functional materials compatible with the TPS. According to the aforementioned, the general objective of this thesis was to develop new functional materials based on molecularly imprinted polymers (MIP) to elaborate chemical microsensors. In the first step of this work, different methods were implemented to characterize the geometrical, chemical and mechanical properties of the materials synthesized by TPS. For example, laser-Doppler vibrometry was used for first time to evaluate the mechanical properties of microstructures fabricated by TPS in a non-invasive way. In the second step, the characterization methodology was used to study the impact of the manufacturing process (i.e. photonic conditions) and the physicochemical parameters that affect the photoreaction (i.e. oxygen inhibition and the nature of the monomer) and the final properties of the materials. Finally, the obtained results enabled the prototyping of chemical microsensors based on MIP. Their molecular recognition properties and their selectivity were demonstrated for the molecule (D-L-Phe) by an optical and a mechanical sensing method

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Cao, Jing. "Creation and orientation of nano-crystals by femtosecond laser light for controlling optical non-linear response in silica-based glasses." Thesis, Université Paris-Saclay (ComUE), 2017. http://www.theses.fr/2017SACLS055/document.

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En raison d’un désordre aléatoire à longue distance, un verre présente une symétrie d'inversion telle que la génération de seconde harmonique (GSH) est interdite. Cependant, par irradiation avec un laser femtoseconde (fs) très focalisé, il est possible de précipiter des cristaux optiquement non linéaires, et de rompre la symétrie d'inversion et donc d'induire une GSH. De plus, ceci peut être réalisé localement en trois dimensions. Pour la démonstration, on a appliqué, dans le système vitreux Li₂O-Nb₂O₅-SiO₂ le mode opératoire décrit ci-dessous qui permet la formation de cristaux de LiNbO₃, hautement optiquement non linéaire. La procédure est la suivante : 1) ajustement de la composition chimique du verre pour obtenir un verre suffisamment sensible au laser fs ; 2) contrôle des paramètres du laser (durée d'impulsion, fréquence de répétition des impulsions, vitesse de balayage du faisceau, énergie d'impulsion…) pour obtenir des nanocristaux avec répartition spatiale et taille correcte. En outre, la taille de la zone affectée doit être limitée ; 3) contrôle de l'orientation des nanocristaux. On montre qu'il est possible de satisfaire à cette condition, en contrôlant l'orientation de la polarisation du laser. Ceci a été montré par la méthode de rétrodiffusion d'électrons de diffraction (EBSD). En d'autres termes, ce processus peut être contrôlé directement avec la lumière. En outre, la spectroscopie par rayons X à dispersion d'énergie couplée à la microscopie à transmission électronique à balayage (STEM /EDS) et la microscopie électronique à transmission a révélé une microstructure orientable similaire à celle appelée nanoréseaux formée dans silice. L'originalité est que les nanocristaux optiques non linéaires texturées noyées dans un réseau de "murs" vitreux, sont alignés perpendiculairement à la direction de polarisation du laser. Il en résulte que la biréfringence et la propriété optique non linéaire peuvent être maîtrisées ensemble. Ceci est une percée dans ce travail de thèse. Ces résultats mettent en évidence des modifications spectaculaires de verre par rayonnement laser fs. Avec de nouvelles améliorations dans les techniques de fabrication, l'application de ce travail est de parvenir à réaliser un guide d'ondes biréfringent doubleur ou changeur de fréquences
Due to random disorder, a glass exhibits inversion symmetry such that second harmonic generation (SHG) is forbidden. However, by irradiation with a tightly focused femtosecond (fs) laser, it is possible to induce nonlinear optical crystal precipitation, in order to break the inversion symmetry and thus to induce SHG. Moreover, this can be achieved locally in three dimensions. For demonstration, we applied the procedure described below in the glass system Li₂O-Nb₂O₅-SiO₂ that allows the formation of LiNbO₃ crystal, a highly non linear optical one. The procedure is thus the following: 1) adjustment of the glass chemical composition for obtaining a glass sensitive enough to fs laser. 2) control of the laser parameters (pulse duration, pulse repetition rate, speed of beam scanning, pulse energy…) for obtaining nanocrystals with correct space distribution and size. In addition, the size of the affected zone has to be limited. 3) control of the orientation of the nanocrystals. We show that it is possible to fulfill this condition by controlling the laser polarization orientation. This has been achieved by electron backscatter diffraction method (EBSD). In other words, this process can be controlled with light directly. In addition, energy dispersive X-ray spectroscopy coupled to scanning transmission electron microscopy (STEM/EDS) and transmission electron microscopy revealed an orientable microstructure similar to the one called nanogratings form in silica. The originality here is a textured nonlinear optical nanocrystals embedded in a network of “walls” made of vitreous phase, aligned perpendicular to the laser polarization direction. It results that birefringence and nonlinear optical property can be mastered in the same time. This is a highly valuable aspect of the work. These findings highlight spectacular modifications of glass by fs laser radiation. With further improvements in the fabrication techniques, the application of this work is to achieve SHG waveguide and birefringence-based devices

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Arnoux, Caroline. "Optimisation d'un procédé d'impression 3D haute résolution à deux photons basé sur la fabrication en parallèle dans des résines photosensibles non-linéaires." Thesis, Lyon, 2021. http://www.theses.fr/2021LYSEN004.

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La structuration sub-micrométrique de grandes surfaces avec une très bonne résolution spatiale pourrait ouvrir de nouvelles frontières dans de nombreux domaines, tels que le stockage de données optiques 3D, la biomédecine ou les micro-dispositifs mécaniques et optiques. Parmi les différentes techniques de fabrication additive, la polymérisation biphotonique a suscité un grand intérêt en raison de sa résolution spatiale, sous la limite de diffraction de la longueur d'onde considérée. Néanmoins, cette technique souffre d'une vitesse d'écriture limitée et d'un coût d'exploitation élevé qui ralentissent son entrée sur le marché. Le but de ce projet de thèse est d'accroitre la vitesse de fabrication par polymérisation biphotonique en fabriquant plusieurs structures en parallèle grâce à la combinaison d’une source laser appropriée et d’éléments optiques diffractifs (EOD) avec une résine à faible seuil de polymérisation. Dans ce cadre, deux nouveaux photoamorceurs biphotoniques ont été synthétisés et caractérisés finement au moyen de multiples techniques (spectroscopies linéaire et non-linéaire, spectroscopie de résonance paramagnétique électronique, voltampérométrie cyclique, microfabrication, spectroscopie Raman). Leur utilisation au sein d’un mélange de monomères acrylates choisis a permis de mettre en évidence le fort potentiel de ces nouveaux amorceurs, comparé à ceux de la littérature. Les seuils de polymérisation ainsi que les dimensions des structures fabriquées ont été déterminés et corrélés à un modèle mathématique. Une méthode de quantification des rendements quantiques de photoamorçage combinant l'actinométrie chimique et la spectroscopie RMN du fluor a été proposée. L’impression simultanée en parallèle de 121 structures a été réalisée, nous conduisant à soulever les problèmes liés aux effets de proximité dans de telles conditions de fabrication ainsi qu’à proposer des voies d’amélioration
The fast patterning of sub-micrometric structures with high three-dimensional (3D) spatial resolution over a large area could open new frontiers in many fields such as 3D optical data storage, biomedicine or mechanical and optical micro-devices. Among the various additive manufacturing techniques, two-photon polymerization (TPP) has attracted a high level of interest due to the spatial resolution it offers, below the diffraction limit of the wavelength used. Nevertheless, this technique suffers from a limited writing speed and a high operating cost which slow down its entry on the market.The goal of this thesis project is to increase the building speed of TPP by fabricating several structures in parallel thanks to the combination of an appropriate laser source and diffractive optical elements (DOE) with a low polymerization threshold resin. In this framework, two new two-photon photoinitiators were synthesized and finely characterized using multiple techniques (linear and nonlinear spectroscopies, electron paramagnetic resonance spectroscopy, cyclic voltammetry, TPP microfabrication, Raman spectroscopy), highlighting their strong potential compared to benchmarks. The polymerization thresholds and the dimensions of the manufactured structures were determined and correlated to a mathematical model. A method for quantifying photoinduced radical generation quantum efficiencies by combining chemical actinometry and 19F NMR spectroscopy has been proposed. Simultaneous parallel printing of 121 structures was performed, revealing issues related to the proximity effects under such fabrication conditions, which we partially solved

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RIZZUTI, ILARIA FRANCESCA. "STRENGTHEN OF DPNS FEATURES FOR THERANOSTIC APPLICATIONS AND MECHANICAL-CONTROL OF CHEMOTHERAPEUTIC EFFICACY THROUGH MODULATION OF CELL PROLIFERATION." Doctoral thesis, Università degli studi di Genova, 2020. http://hdl.handle.net/11567/1000310.

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Solid tumors are complex biological structures which are composed of cellular and matrix components, everything being perfused by blood vessels. During tumor development, modifications of both biochemical and mechanical parameters are observed and can feedback on one another. Cancer cells constantly interact with their mechanical environment and the whole tissue is mostly confined by its surrounding. Compressive mechanical stress develops in part from cell proliferation and could eventually result in the clamping of blood vessels leading to increased interstitial fluid pressure (hydrostatic pressure). The consequent hypoperfusion poses important obstacles to drug delivery and nanomedicines. In fact, the tortuous tumor microvasculature has blood velocities up to one order of magnitude lower compared to healthy capillary networks. Moreover, the fast angiogenesis during tumor progression leads to high vascular density in solid tumors, large gaps exist between endothelial cells in tumor blood vessels, and tumor tissues show selective extravasation and retention of macromolecular drugs (Enhanced Permeation Retention – EPR – effect). These effects have served as a basis for the development of drug delivery systems which are aimed at enhancing tumor tissue targeting and drug therapeutic effectiveness. Over the last 15 years, a plethora of materials and different formulations have been proposed for the realization of nanomedicines. Yet, drug-loading efficiency, sequestration by phagocytic cells, and tumor accumulation of nanoparticle-loaded agents - nanomedicines - are sub-optimal. Starting from these considerations, during my PhD, I studied two complementary approaches: in the first two years my work was focused on implementing the characteristics of Discoidal Polymeric Nanoconstructs designed with controlled geometries and mechanical properties. In the last year, I investigated the role of mechanical stress on chemotherapeutic efficacy. More precisely, this work first reviews the use of deformable discoidal nanoconstructs (DPNs) as a novel delivery strategy for therapeutic and imaging agents. Inspired by blood cell behavior, these nanoconstructs are designed to efficiently navigate the circulatory system, minimize sequestration by phagocytic cells, and recognize the tortuous angiogenic microvasculature of neoplastic masses. In this work, the synthesis, drug loading and release, and physico-chemical characterization of DPNs were enhanced with particular emphasis on the ability to independently control size, shape, surface properties, and mechanical stiffness. Two different loading strategies were tested, namely the straightforward “direct loading” and the “absorbance loading”. In the former case, the agent was directly mixed with the polymeric paste to realize DPNs whereas, in the latter case, DPNs were first lyophilized and then rehydrated upon exposure to a concentrated aqueous solution of the agent. Under these two loading conditions, the encapsulation efficiencies and release profiles of three different molecules and their corresponding prodrugs were systematically assessed (1,2-Distearoyl-sn-glycero-3-phosphorylethanolamine lipid chains or 1 kDa PEG chains were directly conjugated with Cy5.5 or methotrexate and Doxorubicin). Moderately hydrophobic compounds with low molecular weight showed encapsulation efficiencies of 80%, with absorption loading (direct loading has efficiencies around 1%). The DOX-DPN showed on triple negative breast cancer cells a toxicity comparable to free DOX. Preliminary in vivo preliminary studies conducted with directly loaded Cy5-DPN demonstrated a fairly solid integration of the imaging compound with the polymer matrix of the particles. The second part of the work dissect what happens to free drugs or to drugs carried by nanovectors once they reach the tumor site. As we mention above, the elevated mechanical stress derived from tumor progression could result in blood vessels clamping with consequent reduction of drug efficacy. It is quite obvious to imagine that if the drug fails to reach the tumor it cannot act on it. Indeed, mechanical stress within the tumor site is present from the early stages of the disease. Our goal was to understand what happens when mechanical stress is not yet so large enough to fully collapse the blood vessels. Are there mechanical alterations that can affect the efficacy of a chemotherapeutic? We studied how mechanical perturbations of the tumor microenvironment could contribute to the mechanical-form of Gemcitabine drug resistance. Specifically, we developed a new in vitro strategy to mimic the mechanical compression stress induced by the stroma during tumor progression. We embedded pancreatic tumor spheroids into agarose polymeric matrix in order to demonstrate the effect of mechanical compressive stress on tumor proliferation. Then, we validated our results with other types of mechanical stresses. Finally, we investigated the therapeutic efficacy of a proliferation-based chemotherapy: Gemcitabine. Collectively, having the physical cues of cancer in mind, it can be important to cross-fertilize the fields of physical oncology and nanomedicine.

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Pai, Neng-Tsung, and 白能宗. "Investigation of three-dimension lithography using a laser direct writing technique." Thesis, 2008. http://ndltd.ncl.edu.tw/handle/33774043279160500059.

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碩士
國立中興大學
精密工程學系所
96
For a conventional photolithography technique, two-dimensional or three-dimensional patterns always need single or multiple masks to make repetitive exposure processes. Once the masks are contaminated by residual photoresist (PR) or particle defects, the photolithography performance will be easily degraded. In this thesis, the gray-level laser-direct write system was used to make three-dimensional micro components, where the lithography process was designed using an AutoCAD software. Then the pattern software was transformed by the machine code using the DWL66 transform program. During the experiments, the gray level can be controlled by the filtered laser power, photosensitive and development time. After the development and hard bake process, the two dimensional photoresist pattern can be measured using scanning electron microscopy and surface profilometry. The measure results demonstrate that similar microlens and other shapes can be fabricated by controlling the gray level and pattern design. In our direct-write process, the circular and ring patterns were designed to make three-dimension lithography with the 4 mm lens and 10% filter. The PR thickness (AZ 5214E) can be controlled to 2μm under a two-step spin process (1000rpm@10 sec and 2000rpm@25sec). The pre-bake condition was 90℃ for 8min and the best development time was 30 sec. After the exposure process, a post-bake condition of 120℃, 30min was used. Finally, we have successfully performed the two- and three-dimensional lithography without using any conventional photomask.

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Lee, Yuan Chin, and 李源欽. "Study of the optical pickup head for direct laser writing lithography." Thesis, 2015. http://ndltd.ncl.edu.tw/handle/36519931624313554233.

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博士
國立清華大學
光電工程研究所
103
The purpose of this dissertation is to design and implement an optical pickup head to be the light source for direct laser writing lithography. It is difficult to use the commercial optical pickup head as the light source for direct laser writing lithography due to two reasons. Firstly, the lateral stability of the actuator of the optical pickup head is not good since it adopts the six-wired suspension structure. Secondly, the optical power from continuous focusing servo of the optical pickup head may expose the photoresist between two successive exposed spots. To solve the first problem, a special design of a single-axial actuator was proposed. By using two planar springs with three-armed structure, the lateral stability of the actuator was improved. For solving the difficulty of the measurement of the lateral stability of the actuator while the focusing servo is activated, the original “modified push-pull method” was proposed. The measurement results showed that the lateral jitters of the actuator in two orthogonal directions were less than 2 nm. To solve the second problem, a new design of the dual-wavelength optical pickup head with both 405 nm and 650 nm wavelengths was proposed and implemented. The 405 nm beam was used to expose the photoresist, including inorganic and organic photoresists, while the 650 nm beam was used to execute the focusing servo. Numerical aperture of the objective lens was 0.85 at 405 nm. Both focused spots of the two beams by the objective lens were confocal and the detailed procedure of the confocal adjustment was also given. However, since the inorganic photoresist is heat sensitive, we suggest the two focused spots should be separated by at least 1.58 m to prevent from the optical power of the 650 nm spot affecting the exposure of the inorganic photoresist. Finally, the dual-wavelength optical pickup head with the single-axial actuator was used to expose both GeSbSnO inorganic photoresist and EPG 512 organic photoresist. The photoresist was coated on a 4” Si wafer and was spin with the linear velocity of 1 m/s. For the exposure of GeSbSnO photoresist, the minimum diameter of the pierced exposed spots was 0.19 um with 65 nm in depth. For the exposure of EPG512 photoresist, the minimum diameter of the pierced exposed spots was 0.52 um with 1um in depth. Besides, exposed spots with diameter of 0.29 um and with 0.24 um in depth were obtained. The exposure results showed that the procedure of the confocal adjustment was effective, and the dual wavelength optical pickup head was suitable to be used as the light source to expose those devices with feature size near 1 um or below.

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Chu, Liang-Hsiu, and 朱良修. "Design and Analysis of Semiconductor Laser Direct Writing of Lithography System." Thesis, 2018. http://ndltd.ncl.edu.tw/handle/54pppx.

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碩士
國立臺灣科技大學
自動化及控制研究所
106
For the traditional lithography process, the advantage of laser direct writing technology is that it does not require a real mask. Instead, the circuit pattern is defined by focusing the laser beam on the photoresist. A laser scanner based on the dual axis galvanometer, which can quickly locate the focus of the beam at any position on the exposure surface. However, there are problems in the scanning process such as distortion and field curvature. In this study, an optical model for a dual galvanometer laser scanner was constructed. It is used to simulate the dynamic scanning process of galvanometer deflect the laser beam, and considers the optical properties of all used components. In order to realize the maskless lithography of galvanometer scan-based laser direct writing technology, a series of pre-operations on optical simulation were performed. First, the focus position of the deflected beam is investigated by ray tracing, and the scanning range is limited according to the degree of distortion. Then, the intensity of the focus of the scanning position is obtained by field tracing, and the layout of the pattern is scanned with a tilted light spot array. For a line/space pattern with a half period of 50μm, the intensity distribution at the light spot overlap ratio of 40% to 90% is simulated, and the contrast of intensity profile is analyzed with the threshold required for photoresist. When the light spot overlap ratio is 60%, the exposure dose accumulated on the photoresist has the best contrast of 74.22%.

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Do, Danh Bich, and 杜名碧. "Fabrication of optical functional micro/nano periodic structures based on holographic lithography and direct laser writing techniques." Thesis, 2011. http://ndltd.ncl.edu.tw/handle/09570186956031025420.

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博士
國立中正大學
物理學系暨研究所
100
Periodic linear and nonlinear structures have been demonstrated to have unique physical properties due to their singular interaction with electromagnetic waves. These structures allow to have many potential applications, such as creation of a desired photonic bandgap (PBG) materials, i. e., photonic crystal, low loss waveguide and high quality cavity resonator, ultralow threshold laser, nonlinear effect with perfect phase matching, etc. The challenge for researchers is the fabrication of these structures, in a simple manner and an efficient way. Various techniques have been recently studied and demonstrated for this purpose. Among them, holographic lithography (HL) and direct laser writing (DLW) are demonstrated to be very promising, allowing to obtain linear and nonlinear structures, from small to large area, without and with desired defect. Furthermore, these techniques allow to create periodic and quasi-periodic structures at very small length scale, in two dimensions (2D) or three dimensions (3D), which are origine of different applications that cannot be obtained by other techniques. In the framework of this dissertation, we have studied in detail and explored different aspects related to these two techniques to fabricate different kinds of optical functional micro/nano periodic structures, based on polymer materials. Firstly, we investigated a simple and useful method, based on multiple exposure of the two-beam interference pattern, to fabricate different kinds of 2D and 3D periodic linear structures. The experimental results obtained in a suitable fabrication condition, using either SU-8 (negative) or AZ-4620 (positive) photoresist, are in very good agreement with the theoretical predictions. We demonstrated that these structures can be used as templates for creation of photonic bandgap crystals. Indeed, we have used structures obtained by the two-beam interference technique as moulds to grow large-area and uniform vertically aligned 2D periodic ZnO structures by the use of hydro thermal method. These ZnO structure have been also demonstrated to have good superhydrophobicity property. We then studied different parameters that can influence the final fabricated structures; for example, the absorption of material at the exposure light wavelength, the developing effect, the shrinkage of the photoresist, and the energy diffussion, etc. These effects have been demonstrated to be useful for fabricating very special and useful structures, such as microlenses array, nanovein structures, controllable 3D structures, etc. These fabricated structures have been optically characterized and demonstrated be very useful for different applications such as PBG structures. Finally, we demonstrated the fabrication of a 3D polymer quadratic nonlinear (X(2)) grating structure. We have successfully identified the chemical composition and fabrication procedure, which altogether make it possible to realize 3D gratings of a second order nonlinearity in a commonly used polymer. Indeed, by using the one-photon absorption DLW, desired photo-bleached grating patterns were generated in the guest-host disperse-red-1/poly (methylmethacrylate) (DR1/PMMA) active layer. These DR1/PMMA gratings are alternatively assembled with polyvinyl alcohol (PVA), as passive layers, to form an active-passive multilayer structure by using the layer-by-layer process and spin-coating approaches. The corona electric field poling is then applied to obtain a 3D X(2) grating structure. This technique with corresponding fabricated structures are of interest for nonlinear frequency conversion, such as quasi-phase matching second-harmonic generation or multi-color parametric processes.

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HO, CHIH HUA. "Liquid crystals in woodpile photonic crystals: fabrication, numerical calculation and measurement." Doctoral thesis, 2016. http://hdl.handle.net/2158/1036656.

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Both experimental and numerical studies on Liquid Crystal (LC) infiltrated woodpile Photonic Crystal (PhC) are implemented in this thesis. The most well-known optical phenomenon of PhC is photonic bandgap (PBG). It is observed either in frequency or in spatial domain. The former means for a chromatic plane wave propagating though PhC that a range of frequencies do not transmit but reflect. The later means for a monochromatic focused beam passing though PhC that certain angular components do not transmit but deflect or reflect. The most well-investigated optical phenomenon of LC is birefringence. It is due to the strong dielectric anisotropy LC possesses. When the applied stimulations (e.g. electric/ optical field or external heater) are present, the orientation of LC molecules and different refractive indices (e.g. polarization or temperature dependent) are observed. The presence of LC inside PhC not only reduces index contrast (where angular BG appears) but also brings the tunability to such LC-PhC composite device. Therefore band-stop angular filter and sensitive refractometer for liquid material are potential applications controlled by multiple external stimulations. In this thesis, the related physical properties of PhCs and LCs are introduced beforehand. The fabrication of woodpile PhC is also demonstrated. Direct Laser Writing lithography technique is adopted to build microstructures with high resolution up to hundreds of nanometers. A tunable band-stop filter controlled by polarization and temperature is investigated in linear regime. To bridge our investigation to nonlinear regime, dye-doped LC is used to create graded indices inside LC medium corresponding to intensity. Numerical calculations are conducted to the experimental observations. To sum up, LC-PhC composite device possesses very promising features as demonstrated which could be applied into tunable elements in integrated optical systems and its abundant nonlinear properties remains to be explored carefully.

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