Rozprawy doktorskie na temat „Silica fibers laser”

The main topic of this thesis work is photosensitivity and photo-structuring of optical fibers and bulk glass. Although research in the field of photosensitivity in glass and optical fibers has been ongoing for more than three decades, the underlying mechanisms are still not well understood. The objective was to gain a better understanding of the photo-response by studying photosensitivity from a thermodynamic perspective, as opposed to established research focusing on point defects and structural changes, and strain and stress in optical fibers. Optical fibers was mainly used for experimental studies for two reasons; first, photosensitivity in fibers is more pronounced and more elusive compared to its bulk counterpart, and secondly, fibers provide a simplified structure to study as they experimentally can be seen as one-dimensional.Initially, ablation experiments on bulk glass were performed using picosecond infrared pulses. With a design cross section of 40x40 μm, straight channels were fabricated on the top (facing incident light) and bottom side of the sample and the resulting geometries were analyzed. The results show a higher sensitivity to experimental parameters for bottom side ablation which was ascribed to material incubation effects. Moreover, on the top side, the resulting geometry has a V-shape, independent of experimental parameters, related to the numerical aperture of the focusing lens, which was ascribed to shadowing effects.After this work, the focus shifted towards optical fibers, UV-induced fiber Bragg gratings (FBGs) and thermal processing with conventional oven and with a CO2 laser as a source of radiant heat.First, a system for CO2 laser heating of optical fibers was constructed. For measuring the temperature of the processed fibers, a special type of FBG with high temperature stability, referred to as "Chemical Composition Grating" (CCG) was used. A thorough characterization and temperature calibration was performed and the results show the temperature dynamics with a temporal resolution of less than one millisecond. The temperature profile of the fiber and the laser beam intensity profile could be measured with a spatial resolution limited by the grating length and diameter of the fiber. Temperatures as high as ~ 1750 °C could be measured with corresponding heating and cooling rates of 10.500 K/s and 6.500 K/s.Subsequently, a thorough investigation of annealing and thermal regeneration of FBGs in standard telecommunication fibers was performed. The results show that thermal grating regeneration involves several mechanisms. For strong regeneration, an optimum annealing temperature near 900 C was found. Two different activation energies could be extracted from an Arrhenius of index modulation and Braggv iwavelength, having a crossing point also around 900 °C, indication a balance of two opposing mechanisms.Finally, the thermal dynamics and spectral evolution during formation of long period fiber gratings (LPGs) were investigated. The gratings were fabricated using the CO2 laser system by periodically grooving the fibers by thermal ablation. Transmission losses were reduced by carefully selecting the proper processing conditions. These parameters were identified by mapping groove depth and transmission loss to laser intensity and exposure time.
Huvudtemana i denna avhandling är fotokänslighet och fotostrukturering av optiska fibrer och bulk glas. Trots att forskning inom fotokänslighet i glas och optiska fibrer har pågått under mer än tre decennier är de bakomliggande mekanismerna ännu inte klarlagda. Syftet var att få en bättre förståelse för fotoresponsen genom att studera fotokäsligheten ur ett termodynamiskt perspektiv, i motsats till etablerad forskning med fokus på punktdefekter och strukturförändringar, samt mekaniska spännings effekter i optiska fibrer. Optiska fibrer användes för flertalet av de experimentella studierna av två skäl; för det första är fotokänsligheten i fibrer större och dessutom vet man mindre om bakomliggande mekanismer jämfört med motsvarande bulk glas, och för det andra kan fibrer vara enklare att studera eftersom de experimentellt kan ses som en endimensionell struktur.Inledningsvis utfördes ablaherings experiment på bulk glas med en infraröd laser med pikosekund pulser. Raka kanaler med ett designtvärsnitt på 40x40 μm tillverkades på ovansidan (mot infallande ljus) och bottensidan av provet och de resulterande geometrierna analyserades. Resultaten visar en högre känslighet för variationer i experimentella parametrar vid ablahering på undersidan vilket kan förklaras av inkubations effekter i materialet. Dessutom är den resulterande geometrin på ovansidan V-formad, oavsett experimentella parametrar, vilket kunde relateras till den numeriska aperturen hos den fokuserande linsen, vilket förklaras av skuggningseffekter.Efter detta arbete flyttades fokus mot optiska fibrer, UV inducerade fiber Bragg gitter (FBG), och termisk bearbetning med konventionell ugn samt även med en CO2-laser som källa för strålningsvärme.Först konstruerades ett system för CO2-laservärmning av fibrer. För mätning av temperaturen hos bearbetade fibrer användes en speciell sorts FBG med hög temperaturstabilitet, kallade ”Chemical Composition Gratings” (CCG). En grundlig karaktärisering och temperaturkalibrering utfördes och temperaturdynamiken mättes med en tidsupplösning på under en millisekund. Temperaturprofilen i fibern, och laserns strålprofil, kunde mätas med en spatiell upplösning begränsad av gitterlängden och fiberns diameter. Temperaturer upp till ~1750 °C, vilket är högre än mjukpunktstemperaturen, kunde mätas med korresponderande uppvärmnings- och avsvalningshastighet på 10.500 K/s och 6.500 K/s.Därefter gjordes en omfattande undersökning av värmebearbetning och termisk regenerering av FBG:er i telekomfiber. Resultaten visar att termisk gitter-regenerering aktiveras av flera olika mekanismer. Värmebearbetning vid en temperatur omkring 900 °C resulterade i starka gitter efter en regenerering vid en temperatur på 1100 °C. Två olika aktiveringsenergier kunde extraheras från en Arrhenius plot avseende brytningsindexmodulation och Braggvåglängd, med en skärningspunkt tillika runt 900 °C, vilket indikerar en avvägning mellan två motverkande mekanismer vid denna temperatur.Slutligen undersöktes temperaturdynamiken och de spektrala egenskaperna under tillverkning av långperiodiga fibergitter (LPG). Gittren tillverkades med CO2-vi iilasersystemet genom att skapa en periodisk urgröpning medelst termisk ablahering. Transmissionsförluster kunde reduceras med noggrant valda processparametrar. Dessa parametrar identifierades genom mätningar av ablaherat djup och transmissionsförlust som funktion av laserintensitet och exponeringstid.

QC 20150924

Les fibres optiques en silice dopées ytterbium sont couramment utilisées pour des applications laser à forte puissance depuis plusieurs années. Ces puissances ne cessent de croître en raison de progrès continus sur les procédés de fabrication des fibres optiques. Cette thèse s’intéresse à l’élaboration de cœurs de fibres optiques en silice vitreuse dopée ytterbium par un procédé plasma (SPCVD). Cette technique a été inventée en 1986 pour la fabrication de fibres optiques de télécommunications et nous l’avons adaptée dans ces travaux de thèse à la fabrication de cœurs de fibres à grande aire effective dopés en terres rares. Dans un premier temps, la mise au point du procédé et des différentes sources d’évaporation des précurseurs est présentée. Les principaux cœurs de fibres élaborés sont très riches en silice, et faiblement dopés en aluminium, en fluor et en ytterbium. L’homogénéité radiale et longitudinale des cœurs est discutée, et plusieurs options sont proposées pour l’améliorer. Dans un deuxième temps, la structure du réseau vitreux des cœurs élaborés ainsi que l’environnement et la dispersion de l’ion Yb3+ au sein du réseau vitreux silicaté sont étudiés. Pour cela, une approche multi-spectroscopique est utilisée : la résonance magnétique nucléaire informe sur l’environnement des noyaux à spin nucléaire non nul 29Si, 27Al et 19F tandis que la résonance paramagnétique électronique à impulsions permet à la fois de sonder spécifiquement l’environnement de l’ion Yb3+ et d’étudier sa dispersion au sein du réseau vitreux. Ces expériences sont complétées par des caractérisations optiques telles que l’absorption et la luminescence des ions Yb3+. Enfin, les cœurs de fibres élaborés par la méthode SPCVD sont caractérisés en cavité laser. L’efficacité de conversion, la qualité de faisceau et la résistance au photonoircissement de plusieurs cœurs aluminosilicatés co-dopés en fluor et en ytterbium sont présentés
Ytterbium-doped silica optical fibers are widely used for high power laser applications for several years. These powers keep on increasing due to continuous improvements in optical fibers fabrication processes. The aim of this PhD is to synthesize ytterbium-doped silica optical fibers’ cores using a plasma process named SPCVD. This method has been created in 1986 for telecommunications optical fibers synthesis, and we have adapted it to fit the fabrication of rare earth-doped large-mode-area optical fiber cores. We first present the development of ways of evaporating low vapor pressure reagents. All the synthesized optical fiber cores are silica-rich, and slightly doped with both aluminum, fluorine and ytterbium. Radial and longitudinal homogeneities are discussed, and we propose several options in order to improve them. Then, the glassy network structure of the fabricated cores and also the neighborhood and dispersal of Yb3+ ion in the silicate network are studied. Thus, we used several spectroscopic studies: nuclear magnetic resonance enables to focus on non-zero nuclear spin nucleus (29Si, 27Al, 19F) whereas electronic paramagnetic resonance is used to probe the neighborhood and the dispersal of Yb3+ ions. We also based our study on optical characterizations as absorption and luminescence of Yb3+ ions. Finally, the fibers’ cores we synthesized using the SPCVD process have been characterized in a laser cavity. We present the power conversion efficiency, the beam quality and the resistance to photodarkening of several ytterbium and fluorine-co-doped aluminosilicate cores

Cette these traite de l'etude du comportement de composants a fibre de silice dopee aux ions de terres rares. Les fibres dopees sont particulierement attractives comme milieu amplificateur: elles permettent des gains d'amplification superieurs a 40 decibels avec des moyens de pompage compatibles avec la technologie des diodes laser semi-conducteur. Les composants etudies sont: l'amplificateur, le laser et la source superluminescente. Des experiences ont permis de montrer qu'une fraction des ions de terre rare dans les fibres se presente sous forme d'agregats de quelques ions. Ceci constitue un des points fondamentaux de cette etude. Un modele analytique est propose. Sa conception simple a permis la description du comportement des composants et une approche quantitative simplifiee de leur optimisation. Les coupleurs selectifs en frequence sont une des deux innovations technologiques experimentees. Ils ont permis le developpement de l'amplificateur a 1. 55 microns et de la source superluminescente a fibre dopee a l'erbium. Les reseaux de bragg photo-inscrits constituent la seconde innovation. Leurs possibilites ont ete testees sur un laser a fibre dopee au neodyme emettant a 1. 08 microns.

This thesis describes an investigation into the suitability of neodymium doped monomode optical fibre as a gain medium for miniature laser systems. Characterisation of the material and parameters required for quantitative analysis of such laser systems are presented in a spectroscopic analysis carried out in the first part of the thesis. Measurements performed in this section also indicate that at room temperature the wide fluorescence bands of the neodymium doped silica fibre are spectrally broadened by a homogeneous process. The behaviour of a longitudinally pumped continuous-wave fibre laser is modelled in the next section followed by the design and realisation of a practical system. Efficiencies of approximately 6% and threshold pump powers of 8-12 mW have been obtained, even under narrow linewidth operation. Tunability over ranges of 45-60nm has also been demonstrated. The thesis is concluded by experiments on pulsed fibre lasers. Q-switching the laser has achieved peak powers of several watts in pulses 180ns wide with good agreement between the results obtained and predicted values. Shorter pulses 450ps wide have been realised by mode-locking a fibre laser. Suggestions for reducing the pulse width further and the effects of material dispersion are also given. Finally modulated pump sources have been investigated and it is shown that synchronous pumping with short pulses has limitations due to dispersion, while resonantly pumping relaxation oscillations is a simple means of obtaining a pulsed output.

A detailed study of fabrication and characterisation of bismuth (Bi) doped silica optical fibre has been investigated. Three different fibre fabrication techniques were applied to study the possible influence on Bi-luminescence: modified chemical vapour deposition (MCVD) and the solution doping technique, MCVD chemicalin- crucible deposition technique and the powder-in-tube (PIT) technique. Spectroscopic absorption and Bi luminescence and fluorescence decay properties under different pumping wavelengths and with different host glass compositions are presented and provide important information for device applications. The influence of unsaturable loss on laser performance is investigated. The feasibility of direct laser diode pumping of Bi-doped fibre lasers at the wavelengths of 915 and 975 nm was examined by measuring excited state absorption in Bi-doped silicate fibres for the wavelength range of 900 -1300 nm. Enhancement in spectroscopic properties of Bi-doped fibre, by H2-loading, has been examined. Bi-doped fibre laser operating in the wavelength region of 1160-1179 nm has been demonstrated. The fibre laser performance at 1179 nm was investigated incorporating different cooling arrangements. The operation of Bi-doped fibre amplifier at 1179 nm, in both low and high input signal regime, was also examined. An all-fibre, narrow-linewidth, high power Yb-doped silica fibre laser at 1179 nm has been demonstrated. Furthermore, theoretical work confirms that the proposed laser architecture can be easily scaled to higher power

Ces travaux concernent la modélisation et la réalisation de fibres optiques micro-structurées, et plus particulièrement de fibres à bandes interdites photoniques actives et passives, à grande aire effective et destinées au transport ou à la génération de faisceaux lasers puissants.Une première partie du travail a porté sur l’étude d’une nouvelle géométrie de fibre micro-structurée - baptisée « fibre de Bragg pixélisée » - étudiée pour l’obtention d’un large cœur, monomode en pratique. Pour cette géométrie la fibre est rendue monomode en ajustant de façon optimale les distances entre les anneaux de haut indice de réfraction (condition dite demi-onde). Une première réalisation a permis de démontrer un diamètre de mode de 26μm à la longueur d'onde 1400nm dans une fibre passive. Un second aspect de ce travail a consisté en des études théoriques et expérimentales menées sur des fibres à bandes interdites photoniques présentant une gaine hétéro-structurée. Dans ces structures, la gaine comporte des résonateurs conçus pour éliminer les modes d’ordre supérieur par filtrage par les pertes. Des diamètres de mode allant de 19μm à 65μm ont ainsi été obtenus en régime monomode à 1050nm dans plusieurs fibres passives utilisées dans des bandes interdites photoniques différentes. Une fibre hétéro-structurée active a également été réalisée: le cœur, en silice pure dopée avec des ions ytterbium, a été obtenu via le procédé Sol-Gel. La fibre issue de cette réalisation a permis l’observation d’un effet laser avec une efficacité de 62.5%, pour un mode présentant un diamètre de 36μm
These works concern the design and realization of micro-structured optical fibers, in particular, large mode area, active and passive, photonic bandgap fibers for high power laser beams generation and delivery. The first part of the work focused on the study of a new geometry of micro-structured fiber - so called "pixilated Bragg fiber" - in order to obtain a large, practically singlemode, core. For that geometry, the fiber is made singlemoded by optimizing the distances between the high index rings (Half wave stack condition). A first realization allowed to report a mode field diameter of 26μm measured at 1400nm wavelength in a passive fiber. The second aspect of this work included theoretical and experimental studies, of photonic bandgap fibers having a hetero-structured cladding. Specially designed resonators are added to the cladding of these fibers in order to eliminate higher order modes. Thus, 19μm to 65μm mode field diameters have been obtained in a singlemode regime at 1050nm wavelength for several passive fibers used in different bandgaps. An active fiber with hetero-structured cladding was also presented: the core was made of pure silica, ytterbium doped, synthesized using the Sol-Gel technique. The realized fiber allowed the observation of a laser emission with an efficiency of 62.5% and a mode field diameter of 36μm

Processing of Si in the semiconductor and solar cell industry has been dominated by the Diode Pumped Solid State (DPSS) Ultraviolet (UV) laser. Recent advances in laser source technology have produced fibre lasers with Master Oscillator Power Amplifier (MOPA) architectures that offer high repetition rates, high operational efficiencies, and pulse modulation controls exceeding those of typical Q-switched DPSS lasers. The aim of this research is to investigate 1 μm fibre laser machining of Si with a view to identifying the influential laser parameters for optimum processing of high quality, high efficiency micro drilling and surface texturing applications. A secondary aim is to develop a greater understanding of the laser material interactions and material removal mechanism when using fast rise-time nanosecond laser pulse envelopes. The IR fibre laser was able to perform percussion drilling and single pulse machining on the polished Si over a range of intensities up to 1.22 GW/cm2. With the optimum parameters, the micro-sized holes generated by the IR laser have a well defined edge, no heavy recast and no cracks. With a pulse shape of fast rise time (<7.5 ns for a 10-90% rise in signal), a high front peak power zone (approaching 14 kW) and an energetic long tail (40-180 ns), the absorption coefficient of Si at IR wavelength increased dramatically with time and temperature due to the fact that the liquid Si has a metal like absorption behavior. As a result, Si was quickly melted and the rest of pulse energy was able to remove the liquid Si effectively. The machining process left a limited amount of resolidified melt droplets and vapor condensates, which could be washed off ultrasonically. The drilling process was energy efficient when melt expulsion dominated the machining mechanism (0.08-0.2 mJ pulse energy depending on the pulse durations). The low energy pulse (~0.2 mJ) can achieve similar depth as the high energy pulse (~0.7 mJ), so high repetition rates of 100 kHz can be used to instead of 25 kHz, resulted in high processing speed. In addition, by comparing the single pulse machining with the state of the art UV laser, the IR fibre laser machined deeper features and better surface finish in the pulse energy region of >0.07 mJ. With the pulse shaping capability, the material properties can be varied and the wavelength factor can be minimized. The results suggest that applications like microvia drilling can now be carried out with the more flexible and low cost IR fibre laser. The increased repetition rates of fibre laser can increase production speed to satisfy the needs of drilling ~10 thousands holes per second, required by the modern semiconductor and solar cell production. The shortened optical penetration length of 1 μm wavelength laser on Si with increasing temperature and sufficient thermal diffusion length resulted from the asymmetrical fibre laser pulse and the dynamic properties of Si produced a thick liquid layer. A one-dimensional heat conduction model based on the surface heating source predicted that this superheated liquid layer was able to stay above 4706 K (0.905 times the thermal critical temperature 5200 K of Si) for longer than 70 ns to induce explosive boiling. This proposed material removal mechanism was also confirmed by the shadowgraph images, showing particulates ejection lasting up to ten microseconds after the laser pulse. The estimated hole depth based on the explosive boiling alone were different from the measured ones at varying peak power densities (<1.22 GW/cm2) but fixed pulse duration (200 ns), since Si was removed by a mixture of mechanisms. With varying pulse durations (40-200 ns) but fixed peak power density (~0.63 GW/cm2), the estimated depth based on the explosive boiling was in close agreement with the measured ones (6% difference on average). The SEM images at this power density showed a micron- /submicron-sized debris field, which was also observed with the explosive boiling in the past. Although the improved quality of Si machining was demonstrated with the 1 μm MOPA based fibre laser, the setup of this system was only applicable to surface texturing, blind holes and through holes of less than 100 μm in depth. Further research is required to demonstrate the capability of more energetic pulse with higher peak power and large pulse duration range to explore more machining options.

Afin de poursuivre leur montée en débit, les composants des télécommunications par fibre optique nécessitent l'élaboration de nombreuses briques de base : laser, modulateur, photo-détecteur, multiplexeur... et leur intégration avec les circuits de traitement du signal. Cette thèse a pour objectifs de concevoir et de caractériser ces différentes briques actives et passives en utilisant la technologie hybride III-V/Si. Ces briques sont ensuite utilisées dans des circuits photoniques intégrés (PIC) complets d'émission et de réception, qui présentent des avantages tels qu'une. taille réduite, une consommation et un coût de fabrication faibles. . Après une partie d'introduction, plusieurs éléments passifs sont étudiés en détail dans la 2ème partie : guides d 'ondes, virages, diviseurs de puissance, croisements de guides et hybride 90°. Tous ces dispositifs présentent de bonnes performances compatibles avec leur utilisation dans les PICs.La 3ème partie traite le problème du (dé)-multiplexage en longueur d'onde. Trois dispositifs sont étudiés : le démultiplexeur basé sur des résonateurs en anneau, des réseaux échelle et des AWG (arrayed waveguide grating). Pour les réseaux échelles, des performances à l'état de l'art ont été démontrées, d'une part sur un composant de 16 canaux séparés de 100GHz et d'autre part sur un composant de 4 canaux séparés de 20nm avec un profil aplati. Une méthode de simulation d'AWG a ensuite été présentée avec des résultats expérimentaux et théoriques à l'appui. La dernière partie traite des composants dits "actifs" et de l'intégration de toutes les fonctions précédentes dans des circuits photoniques intégrés. Les composants actifs étudiés sont les lasers, les Amplificateurs optiques en semi-conducteurs (SOA), les modulateurs à électro-absorption (EAM) et enfin les jonctions PN sur silicium comme modulateur de phase. Les PICs présentés sont d'abord deux générations de laser accordable intégré avec un EAM avec une transmission à 10Gbit/s sur 50km. Puis sont étudiés des modulateurs I/Q avec source laser accordable intégrée, d'une part avec des jonctions PN en silicium et d'autre part avec des EAM comme modulateurs pour des débits cibles de 25Gbaud/s.Une conclusion générale est tirée à la fin de la thèse. Des perspectives à court et moyen termes sont également tracées
In order to follow the new needs in terms of optical bandwidth, optical fiber communications require the elaboration of numerous building blocks: laser, modulator, photo-detector...and their integration with signal processing circuits. This thesis has for objective the conception and caracterisation of various active and passive building blocks using the hybrid III-V/Si technology. These building blocks are then used in photonic integrated circuits (PIC) with all the necessary emission and reception functions. This enables a reduced footprint, a lower power consumption and fabrication cost.After an introduction section, several passive elements are studied in detail in the second part: waveguides, bends, power splitters, waveguide crossings and hybrid 90°. All these designs present good performances compatible with their integration in PICsThe third part treats the problem of wavelength (de)-multiplexing. Three types of device were studied: a demultiplexer based on ring resonators, echelle gratings and arrayed waveguide gratings (AWG). For the echelle gratings, state-of-the-art performances were demonstrated, first on a sample with 16 channels separated 100GHz and on the other hand a sample with 4 channels separated 20nm with a flettened profile. A simulation method for the AWG was presented with experimental and theoretical results to support the method.The last part is about "active" devices and the integration of all the previous designs in PICs. The studied active components are the lasers, semi-conductor optical amplifiers (SOA), electro-absorption modulators (EAM) and finally silicon PN junctions used as phase modulators. Two generations of a tunable laser integrated with an EAM were studied with a transmission at 10Gbit/s over 50km. The next section studied I/Q modulators with an integrated tunable laser source, using either PN silicon junction modulators or EAM with a target speed of 25Gbaud/s.A general conclusion is drawn at the end of the thesis. Short term and mid-term perspectives were also drawn

Abstract The demands toward the development of simple and cost-effective fabrication methods of metallic structures with high lateral resolution on different substrates - applied in many fields of technology, such as in microelectronics, optoelectronics, micromechanics as well as in sensor and actuator applications - gave the idea to perform this research. Due to its simplicity, laser-assisted chemical liquid-phase deposition (LCLD) has been investigated and applied for the metallization of surfaces having practical importance (Si, GaAs, SiO2, Si3N4, etc.) since the beginning of the 80s. By the invention of novel substrates (polyimide, porous silicon), it was adequate to work out new precursors or just adopt old ones and optimise LCLD in order to fabricate metallic micro-patterns upon these materials for various purposes. According to the motivations mentioned above, LCLD was utilized for the fabrication of palladium (Pd) micro-patterns on polyimide (PI), polyimide/copper flexible printed circuit boards (PCBs), fused silica (SiO2) and silicon (Si). The selective metallization of porous silicon (PS) has been carried out with nickel (Ni). Depending on the types of lasers, either the focusing (Ar+ laser beam) or diaphragm projection (KrF and XeCl excimer laser pulses) method was employed. In the course of the work, various precursors of the corresponding metals have been investigated and utilized. In the beginning, the pyrolytic decomposition of palladium-amine complex ions ([Pd(NH3)4]2+) on PI by a scanned and focused Ar+ laser beam was optimised and discussed. Thick (up to several micrometers) and narrow (~ 10 μm) Pd conductor lines with electrical conductivity close to that of the bulk were obtained. In the continuation of these investigations, the precursor was developed further. [Pd(NH3)4]2+ was mixed with the solution of formaldehyde (HCOH) in order to induce the reduction of the metal complex ions. To our knowledge, we were the first - so far - who applied this solution and described the reaction. With the proper choice of the laser parameters, thin Pd films as catalyst layers for electroless copper plating were deposited utilizing Ar+ and excimer lasers as well. The chemically plated copper deposits - upon the obtained Pd film - have excellent electrical and good mechanical properties. In the second part of the thesis, three practical applications (metallization of via holes drilled in PI/Cu flexible PCBs, end-mirror fabrication on single-mode optical fibers, and carbon nanotube growth on Pd activated Si and Si/SiO2 substrates) of Pd LCLD were realized. The previously presented [Pd(NH3)4]2+ and [Pd(NH3)4]2+/HCOH precursors were employed for creating the catalyst Pd layers for the carbon nanotube chemical vapor-phase deposition and for the autocatalytic electroless chemical copper plating, respectively. Finally, a simple novel method was introduced for the area-selective metallization of PS. Since the surface of PS reduces spontaneously most metals from their aqueous solutions, it is difficult to realize localized metal deposition from liquid-phase precursors on it. We proposed the application of a stable Ni plating bath from which the metal deposits only when the PS is irradiated with photons having wavelength shorter than 689 nm, thus making possible an area-selective laser-assisted metal deposition. The deposited metal structures and patterns were analysed by field emission scanning electron microscopy (FESEM) equipped with energy dispersive spectrometer (EDS), by the milling and imaging modes of a focused ion beam system (FIB), optical microscopy, profilometry, resistance, and by reflectance measurements.

Ce memoire traite de la photosensibilite de fibres optiques en silice sous l'effet d'insolations realisees a l'aide d'un laser a arf. La realisation de l'etude a necessite la mise en place d'un nouveau dispositif d'inscription de reseaux de bragg. Les variations d'indice de refraction photoinduites dans les fibres optiques sont estimees en mesurant les caracteristiques spectrales de reseaux de bragg photoinscrits. Nous presentons une etude detaillee des conditions d'utilisation de ce dispositif. Nous discutons des hypotheses usuellement formulees lors de l'exploitation de la mesure des caracteristiques spectrales des reseaux de bragg. La seconde partie du memoire porte sur la photosensibilite de fibres dont le cur est dope par de l'oxyde de germanium. Nous montrons que les inscriptions de reseaux de bragg sont plus rapides lorsque #p = 193 nm que lorsque #p 244 nm. Cependant, lors de l'utilisation du laser a arf, l'insolation conduit frequemment a des cinetiques de croissances de reseaux de type iia. L'etude des mecanismes microscopiques mis en jeux lors des insolations uv nous a amene a proposer une methode originale d'utilisation du modele de kramers-kronig. L'insolation d'une fibre en silice par un rayonnement ultraviolet peut se traduire par differents effets indesirables. L'etude de la photosensibilite de fibres aluminosilicates dopees par des ions erbium a permis de mettre en evidence le caractere penalisant pour la realisation de lasers a fibres, des insolations realisees sur des fibres prealablement hydrogenees. Par ailleurs, nous avons etudie la photosensibilite d'un type de fibres en silice a cur dope par de l'azote. Il a ete possible d'induire des variations d'indice de refraction superieures a 110##3. Ces variations d'indice de refraction photoinduites sont extremement resistantes a l'elevation de temperature et aux radiations gamma.

Ce mémoire se compose de deux parties, la première consacrée à l'étude des processus multiphotoniques se produisant dans des fibres optiques fortement dopées avec des ions er3+ et yb3+, et la seconde à l'étude des défauts induits par différents traitements dans des fibres germanosilicates. En étudiant la spectroscopie d'émission des fibres fortement dopées, sous excitations visibles (488 nm) et infrarouge (790 - 880 nm), nous mettons en évidence les différents mécanismes aux émissions bleues, vertes et rouge observées. Deux principaux types de processus d'up - conversion peuvent alors être distingués : ceux faisant appel aux transferts d'énergie Yb er et ceux faisant intervenir le phénomène d'absorption dans l'état excité (ESA). L'influence de la longueur de fibre et des concentrations en ions de terre rare sur les efficacités respectives de chacun de ces deux mécanismes est ensuite abordée. Après une présentation bibliographique des différents défauts dans la silice et les fibres germanosilicates, nous présentons le phénomène appelé dépendance modale du spectre d'émission d'une fibre optique, c'est-à-dire la variation du spectre d'émission d'une fibre en fonction du mode excité. L'évolution avec la température d'une bande d'émission centrée autour de 600 nm nous permet ensuite d'attribuer cette émission à des radicaux péroxys. Nous montrons alors que ces radicaux péroxys peuvent être photoinduits dans le CUR des fibres par irradiation intense à 488 nm. Enfin, nous étudions par spectroscopie Raman et spectroscopie d'émission les défauts générés dans deux types de fibres germanosilicates irradiées à 240 nm. Une technique de filtrage spatial du mode excité permet alors de séparer les défauts photoinduits dans le CUR de ces fibres de ceux localisés près de l'interface CUR/gaine

Carbon fibre reinforced ceramic composites (Cf/C-SiC) have been explored as lightweight and durable disc in a friction brake. This composite was manufactured through infiltration of liquid silicon into a Cf/C perform. It has heterogeneous microstructure, composed of three key phases, silicon carbide, Cf/C, and un-reacted residual silicon. The development of the transfer layer on the friction surface of Cf/C-SiC was studied through microstructural image registration of the surface after a range of braking stops on a laboratory-scale dynamometer test rig. When an organic pad was used as the counter face brake pad, it was found that a steady transfer layer was developed in silicon regions right after initial stops; in carbon-fibre/carbon (Cf/C) regions and most of the silicon carbide region, the friction surfaces were unsteady and any possible friction transfer layers were hardly built up. Large voids and cracks/crevices likely became pools to quickly and efficiently collect the transferred materials generated by the friction, but the compacts formed inside the pools were susceptible to be stripped off by further braking operation. Three types of friction surfaces were generalized: type I, the friction transfer layer had a steady relationship with the matrix and respectable longevity; type II, the transfer layer had an unstable relationship with the matrix and poor durability; type III, the friction transfer layer had a steady relationship with the matrix but short lifetime. After testing against organic pads under the laboratory scale dynamometer testing condition, the friction surface of each key phase in Cf/C-SiC composites disc was studied by transmission electron microscopy (TEM). It was found that the transfer layer developed on Si consists of fine particles of metal silicides, silicates and minerals. The substrate damage of Si was not observed, while the precipitates having high oxygen content were found in the substrate. Formation of an interfacial bonding between transfer layer and silicon substrate is believed to be the key factor for the formation of a stable transfer layer on Si. However, the interfacial bonding between transferred materials and SiC was not detected. Kinks are common features developed on the friction surface of SiC. The interface between carbon fibre and carbon matrix was experienced mechanical damage, in form of microcracks, and the transferred material was developed in the interface. Instead of transfer layer, a thin amorphous film, produced by friction induced amorphisation of carbon fibre, was developed on top of carbon fibre.

Les nanomatériaux d'une part et les fibres optiques d'autre part sont au cœur de la révolution scientifique et technologique de ces dernières années. Cette thèse propose d'associer ces deux champs d'applications, afin d'élaborer un nouveau type de fibres optiques présentant un cœur solide nanostructuré par voie sol-gel dans le système silice-zircone dopé terre rare. En s'appuyant sur une étude rhéologique des sols de silice-zircone, ainsi que sur des analyses thermogravimétriques, thermodifférentielles et microstructurales des xérogels de silice-zircone, un protocole d'élaboration d'une telle fibre est mis en place. Les fibres ainsi élaborées sont alors caractérisées expérimentalement d'un point de vue microstructural (MEB, DRX) et d'un point de vue optique (transmission, profil d'indice, dispersion chromatique, pertes). Les propriétés de luminescence des différentes fibres non dopées et dopées avec des ions erbium et/ou ytterbium sont alors étudiées et les mécanismes qui en sont à l'origine sont discutés. L'ensemble de ce travail aboutit à la réalisation de fibres optiques présentant un cœur solide nanocomposite, possédant de bonnes propriétés de guidage et un faible niveau de pertes étant donné les applications visées. Des propriétés de luminescence originales ont finalement été mises en évidence au sein de ces fibres
The nanomaterials and the optical fibers are respectively in the center of the scientific and technological revolution of the last years. This thesis suggest to associate these two fields of applications, in order to elaborate new kinds of optical fibers, which present a solid core nanostructured by the sol-gel process in the silica-zirconia system doped with rare earth ions. Based on a rheological study of silica-zirconia sols, as well as thermogravimetric, thermodifferential and microstructural analysis of silica-zirconia xerogels, an elaboration method of such a fiber is defined. The so elaborated fibers are then characterized on a microstructural point of view (XRD, SEM), as well as on an optical point of view (transmission, index profile, chromatic dispersion, losses). The luminescence properties of the erbium and/or ytterbium doped fibers and undoped fibers are studied and the corresponding mechanisms are discussed. Whole of this work leads to the realization of optical fibers which present a solid nanocomposite core, with good waveguiding properties and weak losses, by taking into account the aimed applications. Original luminescence properties are finally highlighted

La photosensibilite d'un verre (verre massif, fibre ou guide planaire) peut etre definie de facon macroscopique comme une modification de la transmission spectrale et de l'indice de refraction du materiau soumis a une irradiation. L'insolation appropriee (en longueur d'onde, en forme et en intensite) de guides optiques permet de realiser des composants a reseaux de bragg utilises dans le domaine des capteurs et des telecommunications. Dans ce memoire, la stabilite thermique des reseaux de bragg photoinscrits dans les fibres optiques et guides d'onde planaires germanosilicates est etudiee afin de valider des modeles predictifs du vieillissement de ces composants. Ces reseaux ont ete inscrits avec un laser ultraviolet fonctionnant en regime pulse ou en regime continu. Deux methodes ont ete utilisees afin d'etudier la stabilite thermique des reseaux de bragg photoinscrits dans les fibres germanosilicates codopees avec du bore et de l'etain. La methode isochrone consiste a chauffer les reseaux pendant une periode fixe t en faisant varier la temperature t par palier de 50\c. La seconde methode appelee isotherme consiste a chauffer a temperature fixe t en chauffage a permis de valider le concept de l'energie de demarcation e d. Une etude de stabilite thermique des reseaux de bragg inscrits dans des fibres germanosilicates codopees avec du bore ou de l'etain a ete realisee sur une periode de trois ans en utilisant la methode isotherme
Les reseaux inscrits dans les fibres hydrogenees montrent une stabilite thermique inferieure a ceux inscrits dans les fibres non chargees en hydrogene. L'utilisation du bore comme codopant degrade fortement la tenue thermique des reseaux de bragg. Les reseaux de type iia presentent une stabilite thermique largement superieure aux reseaux de type i. Dans la deuxieme partie de ce travail, nous nous sommes propose d'etudier la photosensibilite et la stabilite des reseaux de bragg realises dans les films germanosilicates elabores par voie sol-gel. L'hydrogenation de ces guides a ete necessaire afin d'ameliorer leur photosensibilite. Des etudes de la surface insolee a l'aide de microscope a forces atomiques et du profilometre ont ete effectuees pour mieux comprendre les mecanismes a l'origine de la photosensibilite de ces guides. L'etude de la stabilite thermique des reseaux a ete realisee en utilisant la methode isochrone. Nous avons pu en deduire une estimation de l'amplitude de la variation d'indice photoinduite de l'ordre de 10 3 et les valeurs obtenues sont en accord avec les resultats obtenus dans les verres germanosilicates

Sous l'effet d'une insolation lumineuse (en général ultraviolette), l'indice de réfraction de la plupart des verres de silice se modifie de façon permanente. Cet effet est désigné sous le nom de photosensibilité. Le phénomène se révèle intéressant pour les télécommunications optiques dans la mesure où il permet l'inscription de composants optiques passifs dans le coeur des fibres optiques ou dans des films planaires. Dans le cadre de ce travail de doctorat, nous avons réalisé un ensemble d'études sur la photosensibilité de verres germanosilicates sous l'action d'insolations réalisées à l'aide d'un laser à ArF ([lambda]p=193nm)ou d'un laser à KrF ([lambda]p=248nm). Nous avons étudié trois différentes méthodes de sensibilisation des verres germanosilicates : l'hydrogénation à haute pression et à température ambiante, l'hypersensibilisation UV (hydrogénation, insolation unifor:me et dégazage) ainsi que la méthode de chargement en hydroxyles (élévation thermique à 1000ʿC durant un court instant puis dégazage). D'une part, il s'agissait de comparer les trois méthodes de sensibilisation des fibres optiques germanosilicates en terme d'efficacité, de 'stabilité des procédés et des variations d'indice ainsi que des pertes créées vers 1,5 micron. D'autre part, une étude destinée à préciser les mécanismes de la sensibilisation et les origines des changements d'indice a été présentée dans ce mémoire. A cet effet, nous avons enregistré les spectres d'excès de pertes induits dans l'infrarouge et l'ultraviolet lors de l'insolation UV de lames de préforme ou de fibres germanosilicates sensibilisées.

Ce sujet de recherche ambitionne le contrôle du procédé de réalisation in situ de nano-objets en matrice diélectrique en vue du développement de nouvelles applications. Les matrices de silice comportant des nanoparticules métalliques et semi-conductrices ont suscité un intérêt considérable en recherche fondamentale et appliquée dans le cadre de l’amélioration des catalyseurs, capteurs, ou de composant optiques linéaires et non linéaires. L’utilisation d’une irradiation laser est souvent mentionnée comme méthode prometteuse de croissance localisée. L’objet de ce travail est d’explorer les différentes possibilités de photo-cristallisation de différents types de nanoparticules dans des matrices poreuses ou vitreuses, en faisant varier les conditions de dopage et d’irradiation. Dans cette thèse, des monolithes de silice poreuse produits par le procédé sol-gel ont été post-dopés et densifiés. Une méthode simple, basée sur une irradiation laser, a été développée pour localiser la croissance des nanoparticules semi-conductrices (PbS, CdS) ou métalliques (Au, Ag) à l'intérieur de la matrice de silice poreuse. Les nanoparticules sont précipitées localement sous la surface du xérogels de silice en utilisant un laser visible continu, ou encore dans son volume par une irradiation infrarouge en régime femtoseconde. Il est ainsi apparu qu’une croissance par irradiation en régime femtoseconde dans le domaine infrarouge procède de mécanismes tout à fait différents de ceux d’une synthèse par insolation continue, où le thermique a un rôle prépondérant. Par ailleurs, il est montré que la taille des nanoparticules peut être ajustée par le choix de la concentration des précurseurs dans la solution de post-dopage, par la longueur d’onde du laser, sa puissance ou par la température dans le cas de la précipitation thermique. En outre, différentes méthodes ont été utilisées pour précipiter des nanoparticles métalliques (Ag, Cu) à l’intérieur d’une matrice de silice dense. Ces techniques sont basées soit sur la combinaison d’une insolation laser et d’un traitement thermique, soit uniquement sur des traitements thermiques sous des atmosphères différentes. La structuration spatiale de ces nanoparticules est effectuée par irradiation laser à impulsions, suivie d’un recuit à 600°C. Enfin, le dopage de verre massif par des nanoparticules de Cu a permis d’envisager leur utilisation pour fabriquer des cœurs de fibres optiques micro-structurées dopés. Les premiers tirages de capillaires ont montré que les nanoparticules de Cu peuvent être préservées après avoir subi une fusion à 2000°C
The thesis project aims to master the localization and organization of metallic and semiconducting nano-objects formed inside sol-gel silica materials for novel applications. The nanostructuration method used in this thesis is based on the laser irradiation and, if necessary, heat-treatment. The local character of the matter-light interaction leads to the formation of nano-objects only in the irradiated areas. Hence, it is possible to control the spatial distribution of the nano-crystallites as well as their size distribution by varying the irradiation parameters. In this thesis, porous silica monoliths produced via the sol-gel process were doped and densified. Different kinds of semiconductors (CdS, PbS) and metallic (Au, Ag) nanoparticles incorporated inside the porous SiO2 matrix have been precipitated with the assistance of laser irradiation at room temperature or by an annealing process. The local generation of nanoparticles could be performed directly on the surface of the silica xerogel using a visible continuous laser or inside the volume of the matrix by a femtosecond laser irradiation. Moreover, it has been shown that the nanoparticle size could be adjusted by choosing the concentration of the precursors in the post-doping solution, the laser wavelength, the irradiation power and/or the annealing temperature in the case of thermal precipitation. Furthermore, different methods were used to precipitate metallic nanoparticles (Ag or Cu) inside dense silica matrix. Those techniques are based on laser irradiations and/or heat treatments. Under pulsed laser irradiation, the space selective growth of noble metal nanoparticles was achieved in two steps: first, metallic nucleation centres were generated by the pulsed laser (nanosecond or femtosecond) in the irradiated areas; next, the metallic nanoparticles growth was obtained by annealing at 600°C. Besides, the doping of glassy matrices with copper nanoparticles allows foreseeing their use in the core of microstructured optical fibres. First capillary drawings have shown that the copper nanoparticles can be preserved after undergoing a melting at 2000°C

[EN] The processing of radiofrequency signals using photonics means is a discipline that appeared almost at the same time as the laser and the optical fibre. Photonics offers the capability of managing broadband radiofrequency (RF) signals thanks to its low transmission attenuation, a variety of linear and non-linear phenomena and, recently, the potential to implement integrated photonic subsystems. These features open the door for the implementation of multiple functionalities including optical transportation, up and down frequency conversion, optical RF filtering, signal multiplexing, de-multiplexing, routing and switching, optical sampling, tone generation, delay control, beamforming and photonic generation of digital modulations, and even a combination of several of these functionalities. This thesis is focused on the application of vector processing in the optical domain to radiofrequency signals in two fields of application: optical beamforming, and photonic vector modulation and demodulation of digital quadrature amplitude modulations. The photonic vector control enables to adjust the amplitude and phase of the radiofrequency signals in the optical domain, which is the fundamental processing that is required in different applications such as beamforming networks for direct radiating array (DRA) antennas and multilevel quadrature modulation. The work described in this thesis include different techniques for implementing a photonic version of beamforming networks for direct radiating arrays (DRA) known as optical beamforming networks (OBFN), with the objectives of providing a precise control in terrestrial applications of broadband signals at very high frequencies above 40 GHz in communication antennas, optimizing the size and mass when compared with the electrical counterparts in space application, and presenting new photonic-based OBFN functionalities. Thus, two families of OBFNs are studied: fibre-based true time delay architectures and integrated networks. The first allow the control of broadband signals using dispersive optical fibres with wavelength division multiplexing techniques and advanced functionalities such as direction of arrival estimation in receiving architectures. In the second, passive OBFNs based on monolithically-integrated Optical Butler Matrices are studied, including an ultra-compact solution using optical heterodyne techniques in silicon-on-insulator (SOI) material, and an alternative implementing a homodyne counterpart in germanium doped silica material. In this thesis, the application of photonic vector processing to the generation of quadrature digital modulations has also been investigated. Multilevel modulations are based on encoding digital information in discrete states of phase and amplitude of an electrical signal to enhance spectral efficiency, as for instance, in quadrature modulation. The signal process required for generating and demodulating this kind of signals involves vector processing (phase and amplitude control) and frequency conversion. Unlike the common electronic or digital implementation, in this thesis, different photonic based signal processing techniques are studied to produce digital modulation (photonic vector modulation, PVM) and demodulation (PVdM). These techniques are of particular interest in the case of broadband signals where the data rate required to be managed is in the order of gigabit per second, for applications like wireless backhauling of metro optical networks (known as fibre-to-the-air). The techniques described use optical dispersion in optical fibres, wavelength division multiplexing and photonic up/down conversion. Additionally, an optical heterodyne solution implemented monolithically in a photonic integrated circuit (PIC) is also described.
[ES] El procesamiento de señales de radiofrecuencia (RF) utilizando medios fotónicos es una disciplina que apareció casi al mismo tiempo que el láser y la fibra óptica. La fotónica ofrece la capacidad de manipular señales de radiofrecuencia de banda ancha, una baja atenuación, procesados basados en una amplia variedad de fenómenos lineales y no lineales y, recientemente, el potencial para implementar subsistemas fotónicos integrados. Estas características ofrecen un gran potencial para la implementación de múltiples funcionalidades incluyendo transporte óptico, conversión de frecuencia, filtrado óptico de RF, multiplexación y demultiplexación de señales, encaminamiento y conmutación, muestreo óptico, generación de tonos, líneas de retardo, conformación de haz en agrupaciones de antenas o generación fotónica de modulaciones digitales, e incluso una combinación de varias de estas funcionalidades. Esta tesis se centra en la aplicación del procesamiento vectorial en el dominio óptico de señales de radiofrecuencia en dos campos de aplicación: la conformación óptica de haces y la modulación y demodulación vectorial fotónica de señales digitales en cuadratura. El control fotónico vectorial permite manipular la amplitud y fase de las señales de radiofrecuencia en el dominio óptico, que es el procesamiento fundamental que se requiere en diferentes aplicaciones tales como las redes de conformación de haces para agrupaciones de antenas y en la modulación en cuadratura. El trabajo descrito en esta tesis incluye diferentes técnicas para implementar una versión fotónica de las redes de conformación de haces de en agrupaciones de antenas, conocidas como redes ópticas de conformación de haces (OBFN). Se estudian dos familias de redes: arquitecturas de retardo en fibra óptica y arquitecturas integradas. Las primeras permiten el control de señales de banda ancha utilizando fibras ópticas dispersivas con técnicas de multiplexado por división de longitud de onda y funcionalidades avanzadas tales como la estimación del ángulo de llegada de la señal en la antena receptora. En la segunda, se estudian redes de conformación pasivas basadas en Matrices de Butler ópticas integradas, incluyendo una solución ultra-compacta utilizando técnicas ópticas heterodinas en silicio sobre aislante (SOI), y una alternativa homodina en sílice dopado con germanio. En esta tesis, también se han investigado técnicas de procesado vectorial fotónico para la generación de modulaciones digitales en cuadratura. Las modulaciones multinivel codifican la información digital en estados discretos de fase y amplitud de una señal eléctrica para aumentar su eficiencia espectral, como por ejemplo la modulación en cuadratura. El procesado necesario para generar y demodular este tipo de señales implica el procesamiento vectorial (control de amplitud y fase) y la conversión de frecuencia. A diferencia de la implementación electrónica o digital convencional, en esta tesis se estudian diferentes técnicas de procesado fotónico tanto para la generación de modulaciones digitales (modulación vectorial fotónica, PVM) como para su demodulación (PVdM). Esto es de particular interés en el caso de señales de banda ancha, donde la velocidad de datos requerida es del orden de gigabits por segundo, para aplicaciones como backhaul inalámbrico de redes ópticas metropolitanas (conocida como fibra hasta el aire). Las técnicas descritas se basan en explotar la dispersión cromática de la fibra óptica, la multiplexación por división de longitud de onda y la conversión en frecuencia. Además, se presenta una solución heterodina implementada monolíticamente en un circuito integrado fotónico (PIC).
[CAT] El processament de senyals de radiofreqüència (RF) utilitzant mitjans fotònics és una disciplina que va aparèixer gairebé al mateix temps que el làser i la fibra òptica. La fotònica ofereix la capacitat de manipular senyals de radiofreqüència de banda ampla, una baixa atenuació, processats basats en una àmplia varietat de fenòmens lineals i no lineals i, recentment, el potencial per implementar subsistemes fotònics integrats. Aquestes característiques ofereixen un gran potencial per a la implementació de múltiples funcionalitats incloent transport òptic, conversió de freqüència, filtrat òptic de RF, multiplexació i demultiplexació de senyals, encaminament i commutació, mostreig òptic, generació de tons, línies de retard, conformació de feix en agrupacions d'antenes i la generació fotònica de modulacions digitals, i fins i tot una combinació de diverses d'aquestes funcionalitats. Aquesta tesi es centra en l'aplicació del processament vectorial en el domini òptic de senyals de radiofreqüència en dos camps d'aplicació: la conformació òptica de feixos i la modulació i demodulació vectorial fotònica de senyals digitals en quadratura. El control fotònic vectorial permet manipular l'amplitud i la fase dels senyals de radiofreqüència en el domini òptic, que és el processament fonamental que es requereix en diferents aplicacions com ara les xarxes de conformació de feixos per agrupacions d'antenes i en modulació multinivell. El treball descrit en aquesta tesi inclou diferents tècniques per implementar una versió fotònica de les xarxes de conformació de feixos en agrupacions d'antenes, conegudes com a xarxes òptiques de conformació de feixos (OBFN), amb els objectius de proporcionar un control precís en aplicacions terrestres de senyals de banda ampla a freqüències molt altes per sobre de 40 GHz en antenes de comunicacions, optimitzant la mida i el pes quan es compara amb els homòlegs elèctrics en aplicacions espacials, i la presentació de noves funcionalitats fotòniques per agrupacions d'antenes. Per tant, s'estudien dues famílies de OBFNs: arquitectures de retard en fibra òptica i arquitectures integrades. Les primeres permeten el control de senyals de banda ampla utilitzant fibres òptiques dispersives amb tècniques de multiplexació per divisió en longitud d'ona i funcionalitats avançades com ara l'estimació de l'angle d'arribada del senyal a l'antena receptora. A la segona, s'estudien xarxes de conformació passives basades en Matrius de Butler òptiques en fotònica integrada, incloent una solució ultra-compacta utilitzant tècniques òptiques heterodinas en silici sobre aïllant (SOI), i una alternativa homodina en sílice dopat amb germani. D'altra banda, també s'ha investigat en aquesta tesi tècniques de processament vectorial fotònic per a la generació de modulacions digitals en quadratura. Les modulacions multinivell codifiquen la informació digital en estats discrets de fase i amplitud d'un senyal elèctric per augmentar la seva eficiència espectral, com ara la modulació en quadratura. El processat necessari per generar i desmodular aquest tipus de senyals implica el processament vectorial (control d'amplitud i fase) i la conversió de freqüència. A diferència de la implementació electrònica o digital convencional, en aquesta tesi s'estudien diferents tècniques de processament fotònic tant per a la generació de modulacions digitals (modulació vectorial fotònica, PVM) com per la seva demodulació (PVdM). Això és de particular interès en el cas de senyals de banda ampla, on la velocitat de dades requerida és de l'ordre de gigabits per segon, per a aplicacions com backhaul sense fils de xarxes òptiques metropolitanes (coneguda com fibra fins l'aire). Les tècniques descrites es basen en explotar la dispersió cromàtica de la fibra òptica, la multiplexació per divisió en longitud d'ona i la conversió en freqüència. A més, es prese
Piqueras Ruipérez, MÁ. (2016). Photonic Vector Processing Techniques for Radiofrequency Signals [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/63264
TESIS

In this thesis, improved techniques for biomolecule analysis using capillary electrophoresis (CE) and matrix-assisted laser desorption/ionization-mass spectrometry (MALDI-MS) and hyphenations between those have been presented.A pre-concentration method which is possible to apply in both techniques, has also been investigated. In this work the off-line MS mode has been used either in the form of fractionation (Paper I) or by incorporating the MALDI target in the CE separation system (Paper II).In Paper I, a protocol for CE-MALDI analysis of cyanogen bromide digested bacteriorhodopsin (BR) peptides as model integral membrane protein peptides were established. Also, an improved protocol for partially automated manufacturing of a concentration MALDI-target plate is presented. The design of the targets was suitable for the fractions from the CE. A novel technique for the integration of CE to MALDI-MS using a closed-open-closed system is presented in Paper II, where the open part is a micro canal functioning as a MALDI target window. A protein separation was obtained and detected with MALDI-MS analysis in the micro canal. A method has been developed for detection of monosaccharides originating from hydrolysis of a single wood fiber performed in a micro channel, with an incorporated electromigration pre-concentration step preceding CE analysis in Paper III. The pre-concentration showed to be highly complex due to the fact that several parameters are included that affecting each other. In Paper IV a protocol using enzymatic digestion, MALDI-TOF-MS and CE with laser induced fluorescence (LIF) detection for the investigation of the degree of substitution of fluorescein isothiocyanate (FITC) to bovine serum albumin (BSA), as a contact allergen model system for protein-hapten binding in the skin, is presented. The intention of a further CE-MALDI hyphenation has been considered during the work. In Paper V 2,6-dihydroxyacetophenone (DHAP) was investigated, showing promising MALDI-MS matrix properties for hydrophobic proteins and peptides. 2,5-dihydroxybenzoic acid (DHB) was undoubtedly the better matrix for the hydrophilic proteins, but its performance for the larger and hydrophobic peptides was not optimal. Consequently, DHAP can be used as a compliment matrix for improved analysis of hydrophobic analytes.
QC 20101214

Nonlinear effects occur due to the modification of optical properties of a material medium by the presence of high intensity light such as lasers, resulting in the generation of new frequency components. The availability of low-loss silica fibers has not only led to a revolution in the field of optical communications but also the beginning of a new field of nonlinear fiber optics. Optical fibers have become the nonlinear medium of choice as they can confine high power light over long lengths and provide efficient thermal management. Additionally, fiber laser systems are rugged and compact due to efficient fusion splicing technology and the absence of external optics for alignment. Different applications require fiber lasers having different operating wavelengths, bandwidth, coherence, and/or power. While lasers are typically described as monochromatic or single-frequency sources, it is possible to create lasers with diverse spectral features. Broadband sources such as supercontinuum (SC) or optical frequency comb (OFC) can be generated using nonlinear effects. Depending on the regime of operation, various nonlinear effects become predominant. For example, in case of continuous-wave (cw) anomalously pumped SC, modulation instability (MI) seeded spectral broadening along with the combined effects of Four-Wave Mixing (FWM) and Stimulated Raman Scattering (SRS) results in a broad spectrum. For OFCs, bandwidth scaling is done using FWM. In narrow linewidth systems, Stimulated Brillouin Scattering (SBS) manifests as a threshold phenomenon limiting power scaling. Here, the intensity of scattered light grows exponentially when the incident light exceeds a certain value of threshold power. It was identified that in the aforementioned cases, poor spectral shape and control imposed limitations on system performance and use. In this thesis, we propose simple and easy-to-implement solutions to overcome these shortcomings. Thereby, opening up avenues for these diverse (broadband to narrowband) sources to be used in a wide range of applications. High power cw pumped SC sources have large bandwidth, high average power, and equalized spectra. At low powers, these sources exhibit poor spectral flatness and high sensitivity to the position of pump-wavelength with respect to the zero-dispersion of the nonlinear fiber. Obtaining a pump wavelength agile SC at lower, easily manageable optical powers is attractive for many applications such as imaging, spectroscopy, characterization, test and measurement. But current techniques require the use of complex system design with multiple pump lasers and/or significantly longer lengths of fibers. In this work, a two-stage broadening architecture (to increase pump incoherence) is proposed to improve the spectral flatness and successfully demonstrate for the first time, a cw pump wavelength flexible, low power (80 mW to 550 mW) SC with spectra spanning from 1300 nm to 2000 nm and a 10 dB bandwidth of over 400 nm. The resulting SC generation module is self-standing and uncorrelated with the specifications of the C-band pump source. This offers excellent practical benefits and makes for an ideal source for broadband low power applications. In addition to large bandwidth, OFCs have high temporal coherence and are widely used in Radio frequency (RF) photonics, optical arbitrary waveform generation, ultra-short pulse generation and optical communications. Direct bandwidth scaling of high-repetition-rate electro-optic (EO) frequency combs is limited by the power handling capability of modulators used. Significant bandwidth can be achieved by using nonlinear spectral broadening (in fibers) of a single laser comb, but conventional techniques produce an OFC with uneven spectra and hence limited flatness. Current techniques to improve the OFC profile require the use of complex architectures or optimization algorithms. We identified that by using tailored optical feedback to filter out an optimal set of comb lines, enhanced FWM and power redistribution is achieved, resulting in a smooth, bandwidth scaled OFC. The optimal result demonstrated is a 25 GHz frequency comb spanning 2.5 THz bandwidth in the C-band with ~0.5 W power and 100 usable sub-carriers (i.e., a ten-fold increment compared to the initial EO comb). The effective linewidth of an equalized OFC is greater than its discrete narrow linewidth sub-carriers. Since the enhancement in SBS threshold depends largely on the spectral width, SBS is suppressed in bandwidth scaled systems such as OFCs but becomes a limiting factor in power scaling of narrow linewidth systems. High power narrow linewidth fiber lasers have garnered significant interest over the last decade for their widespread use in industrial, scientific, and directed energy applications. SBS is the lowest threshold nonlinear effect in narrow linewidth cw fiber lasers and occurs as high peak power pulses propagating in the backward direction. These pulses cause catastrophic damage to the system and must be mitigated. While several SBS mitigation techniques exist, optical linewidth broadening through external phase modulation using white noise source (WNS) has become the preferred method for SBS suppression due to its simplicity and continuous tuning of linewidth through noise power and bandwidth control. But it was observed that the enhancement obtained experimentally with WNS was lower than the theoretical estimate. We attribute this to the non-ideal line shape of the WNS broadened laser where the signal tail overlaps with Brillouin gain spectrum causing increased SBS seeding. We anticipated that with better line shape control, the SBS seeding would be greatly minimized resulting in higher output powers. In this work, we synthesize a line shape with faster roll-off and improved flatness by incorporating dual sinusoid and noise modulation (DSNM). The effectiveness of the proposed technique is demonstrated experimentally using an in-house built multi-stage Ytterbium (Yb) doped fiber amplifier by optimizing the pumping scheme, gain fiber lengths, splices, and thermal management techniques to enable power scaling of a 30 mW narrow linewidth seed at 1064 nm to over 1 kW. We compare the results with that of pure WNS modulation at similar linewidths and demonstrate over 2.36X enhancement in SBS limited output power at ~7.3 GHz and >1 kW SBS unlimited output power at ~10.4 GHz in a fully polarization-maintained system. This makes for an excellent source in beam combining applications and remote detection.
Ministry of Electronics and Information technology (NNetra, Visvesvaraya PhD Scheme); Department of Science and Technology, Ministry of Science and Technology, India (NNetra)

This thesis explains architecture and techniques to generate high power, CW supercontinuum laser sources using standard Silica fibers as the nonlinear medium, pumped using high power CW Yb doped fiber lasers. Unlike the pulsed supercontinuum sources, the CW supercontinuum sources offer high average powers leading to spectacular power spectral densities at the output and can be realized at lower costs, in an all fiber architecture, which makes the system more compact and favorable towards power scaling. We have demonstrated a high power, all-fiber, wavelength tunable, fiber laser source that can operate in the L-band region (1.5-1.6 um), based on 6th order cascaded Raman amplification scheme, which can generate ~24 W of output power and is widely tunable from 1560-1590 nm. Using this laser we could pump the HNLF to generate a supercontinuum of ~700 nm bandwidth to powers as high as 35 W which is nearly double the output power than what has been previously demonstrated. To enhance the bandwidth and scale the output power, we have demonstrated a simple but highly impactful solution which uses the standard telecom fiber as the nonlinear medium. The supercontinuum generation module we demonstrated, is essentially a high efficiency cascaded Raman converter, which can take any CW, high power Ytterbium-doped fiber laser as the input and generate an octave spanning supercontinuum with an average power of ~34W, spanning over 1000nm (>1 octave) from 880nm to 1900nm at an efficiency of ~44%. The supercontinuum source exhibited excellent spectral and temporal stability for an extended duration of operation (>1 hour). The most highlighting result reported in this thesis is the record high output power that has been demonstrated from a CW supercontinuum so far. Using the recently proposed nonlinear power combining architecture we could leverage the output power (limited by available pump power) from the telecom fiber based octave spanning, CW supercontinuum. This involves nonlinear spectral power combining of outputs from multiple, independent, Yb lasers operating at different wavelengths as the pump sources, to generate supercontinuum at an efficiency of ~44% with a spectacular PSD of >3mW/nm from 850nm-1350 nm and an impressive PSD of >100mW/nm from 1350nm-1900nm at an output power of ~72 W.

碩士
國立高雄應用科技大學
光電與通訊研究所
96
The trivalent rare-earth-doped silica glasses based on 4f-4f transitions have recently attracted world attention as materials that can be used for high-efficiency fiber lasers. Among these materials, Yb3+-doped silica glass is an exceptionally promising fiber laser gain medium that exhibit highly efficient emission using InGaAs laser diodes as the excitations. The key advantages of the Yb3+-doped silica glass are the absence of intermediated energy levels between the two manifold levels of 2F7/2 ground state and 2F5/2 excited state, which can prevent up-conversion, excited state absorption, and self-quenching by cross relaxation, resulting in maintaining high Yb3+-doped concentration with the longer radiative lifetime. In this study, we used laser heated pedestal growth (LHPG) method to grow crystal fiber, which can grow with small diameters at very fast rate with computer control system. High quality Yb:YAG-silica fibers with a diameter ranging from 105 to 115 μm were grown. After the processes of alloy packaging, grinding, polishing, and coating, we successfully fabricated the Yb:YAG-silica fiber lasers. We discovered that the gradient concentration of Yb3+ ions distributed over the cross-section of fibers is helpful in guiding lights. The absorption, emission spectra and fluorescence lifetime of Yb:YAG-silica at room temperature have also been studied. The Yb3+ absorption band is centered at 976nm. It is also suitable to be pumped by InGaAs diode lasers. The main fluorescence band is also located around 976nm. The fluorescence lifetime of Yb:YAG-silica is about 450 s. The Yb:YAG-silica fiber with high doping concentration is a promising laser material for high power laser output . We have successfully implemented the Ti:sapphire laser (915 nm) pumped Yb:YAG-silica fiber lasers with a lasing wavelength of 1089 nm. The laser operates at a low threshold of 100 mW, and a maximum slope efficiency of 67.2%. The corresponding maximum output power is 654 mW. In the future, we will improve the cooling system, the alloy packaging, and coating to further increase the conversion efficiency and output power.

近年在矽光子學方面的研究日漸增多，主要原因是在高效能電腦，低成本通訊接取網絡及集成光學感應器等各方面有很大的潛在應用。以矽為原材料的各種光學器件已經被廣泛研究，包括電光調制器，光感應器和各式各樣主動及被動器件。但是由於矽是一種間接能隙的物質，即是由電子激發的電子電洞的結合是屬於非輻射躍遷，所以不可以得到光放大和激光器的效果。為了製作集成激光器，已經有很多不同的研究方案，例如在矽波導上摻雜鉺或是混合集成矽和-族半導體。在這篇論文中，我們提出並且論証了一個創新的方案去製作由光纖和矽波導混合而成的激光器，大大簡化了設計和生產過程。
在論文中，我們會集中討論選取光波長的器件及整體結構的設計。在首次的結構設計上，我們利用了分佈在矽波導兩側的布拉格反射鏡作為選取光波長的器件和一小段以鉺摻雜的光纖作為放大器。我們將會詳細形容該器件的設計、模擬效果和實驗結果。我們已經透過實驗証明了單波長的光纖－矽波導混合激光器，其側模抑制超過35分貝。
另一方面，為了製作多波長的光纖－矽波導混合激光器，我們利用微環諧震器來取代分佈在矽波導兩側的布拉格反射鏡作為選取光波長的器件。我們將會討論微環諧震器的設計以及達到穩定多波長的光纖和矽波導混合激光器的設計要求。
Motivated by potential applications for optical interconnects in high performance computing, low cost optical access networks in telecommunications and integrated optical sensors, there has been much research in recent years on silicon photonics. Different silicon-based photonic devices have been studied, including optical modulators, detectors and various types of active and passive components. However, since the bandgap of silicon is indirect, the recombination of carriers injected by electrical pumping is dominated by non-radiative transitions and thus it is not possible to get optical gain via current injection into silicon diodes.
To implement integrated laser, different approaches such as erbium doping on silicon waveguide and hybrid integration of III-V semiconductors on silicon have been investigated. In this thesis, we propose and demonstrate a novel approach for making a hybrid fiber-silicon laser to simplify the design and fabrication processes. We propose the use of Erbium-doped fiber (EDF) to provide gain and silicon devices to provide all the other functionalities needed for a modulated laser.
The thesis focuses on the design of wavelength selective element and the structure of hybrid fiber-silicon laser. The first design includes a silicon waveguide side-cladding distributed Bragg reflector (WSC-DBR) as the wavelength selective component on silicon-on-insulator (SOI) wafer and a short length of EDF as the gain medium. The details of design, simulation and experimental results of the WSC-DBR will be described. Single wavelength WSC-DBR hybrid fiber-silicon laser is demonstrated with a side mode suppression ratio (SMSR) of over 35dB.
We also investigate the use of a micro-ring resonator to replace WSC-DBR for selecting multiple wavelengths. Details of the micro-ring resonator are given and we discuss the requirement and design criteria to achieve stable multi-wavelength lasing.
Detailed summary in vernacular field only.
Detailed summary in vernacular field only.
Detailed summary in vernacular field only.
Fung, Ka Yan.
Thesis (M.Phil.)--Chinese University of Hong Kong, 2012.
Includes bibliographical references.
Abstracts also in Chinese.
ABSTRACTOF THESIS ENTITLED: --- p.ii
ACKNOWLEDGEMENT --- p.v
TABLE OF CONTENT --- p.vii
Chapter 1 --- INTRODUCTION --- p.10
Chapter 1.1 --- Photonic Integrated Circuits --- p.10
Chapter 1.2 --- Silicon Photonics --- p.13
Chapter 1.3 --- Lasers in Silicon --- p.20
Chapter 1.4 --- Motivation --- p.27
Chapter 1.5 --- References --- p.29
Chapter 2 --- ERBIUM DOPED FIEBR AND FIBER LASERS --- p.34
Chapter 2.1 --- Erbium doped fiber --- p.34
Chapter 2.2 --- Multi-wavelength lasers --- p.45
Chapter 2.3 --- References --- p.54
Chapter 3 --- SINGLE CHANNEL HYBRID FIBER-SILICON LASER --- p.59
Chapter 3.1 --- Introduction of Distributed Bragg reflector --- p.60
Chapter 3.2 --- Design of waveguide side-cladding distributed Bragg reflector --- p.63
Chapter 3.3 --- Simulation results of waveguide side-cladding distributed Bragg reflector --- p.66
Chapter 3.4 --- Device fabrication --- p.69
Chapter 3.5 --- Experimental results of waveguide side-cladding distributed Bragg reflector --- p.71
Chapter 3.6 --- Experimental results of hybrid fiber-silicon laser --- p.77
Chapter 3.7 --- Introduction of micro-ring resonator --- p.81
Chapter 3.8 --- Design of race track micro-ring resonator --- p.85
Chapter 3.9 --- Experimental results of race track micro-ring resonator --- p.88
Chapter 3.10 --- Experimental results of hybrid fiber-silicon laser with ring resonator --- p.95
Chapter 3.11 --- Summary --- p.99
Chapter 3.12 --- References --- p.101
Chapter 4 --- DUAL WAVELENGTH HYBRID FIBER SILICON LASER --- p.102
Chapter 4.1 --- Design of micro-ring resonator for dual wavelength --- p.103
Chapter 4.2 --- Experimental results of micro-ring resonator --- p.104
Chapter 4.3 --- Experimental results of dual wavelength hybrid fiber-silicon laser --- p.108
Chapter 4.4 --- Summary --- p.119
Chapter 4.5 --- References --- p.121
Chapter 5 --- DUAL WAVELENGTH VERTICAL GRATING COUPLER --- p.123
Chapter 5.1 --- Introduction of grating coupler --- p.123
Chapter 5.2 --- Design of dual wavelength vertical grating coupler --- p.125
Chapter 5.3 --- Simulation of dual wavelength vertical grating coupler --- p.127
Chapter 5.4 --- Experimental results of dual wavelength vertical grating coupler --- p.135
Chapter 5.5 --- Summary --- p.138
Chapter 5.6 --- References --- p.139
Chapter 6 --- CONCLUSION AND FUTURE WORK --- p.141
Chapter 6.1 --- Conclusion --- p.141
Chapter 6.2 --- Future work --- p.144
Chapter 6.3 --- References --- p.146
Chapter APPENDIX A: --- PUBLICATION LIST --- p.147
Chapter APPENDIX B: --- LIST OF TABLES --- p.149
Chapter APPENDIX C: --- LIST OF FIGURES --- p.150
Chapter APPENDIX D: --- METHODS OF LINEWIDTH MEASUREMENT --- p.155
Chapter APPENDIX E: --- EQUIPMENT INFORMATION --- p.164

碩士
國立中山大學
光電工程研究所
96
Recently, with the escalating demands for optical communication, the need to use broadband laser light sources in optical communication network system has increased. Henceforward, the broadband characteristes of Cr4+:YAG crystal fiber possess signifies its indispensability. Furthermore, Yb3+:YAG-silica also has its advantages in high power laser domain. In this thesis, the crystal fiber grown by the laser heated pedestal growth method is used as the laser gain medium with fused silica packaging technique. Cr4+:YAG double-clad crystal fiber with a core diameter as small as 11 μm was achieved. Moreover, a Yb3+:YAG-silica layer was formed due to the strong inter-diffusion between silica capillary and Yb3+:YAG crystal. When the silica all diffused into the Yb3+:YAG, a Yb3+:YAG-silica fiber with 125-μm core was obtained with waveguide structure. By directly coating the optical thin films onto the end faces of the two types of fibers, the laser configuration is compact and cost effective. Besides, heat dissipation is also improved. By Cu-Al alloy packaging, a record-low Cr4+:YAG double-clad crystal fiber laser was achieved with threshold of 0.75 mW and a record-high slope efficiency of 6.9% at room temperature. And we also successfully fabricate the Yb3+:YAG-silica fiber laser with low threshold (100 mW) and high efficiency (67.2%) at room temperature. In fiber laser development, we have successfully fabricated the coating of high-reflective thin films which match the faces of fiber heterostructure (single cladding and double cladding structures). It forms a cavity with anti-reflectivity for pumping wavelength and high-reflectivity for lasing wavelength. For these reasons, low threshold, high slope efficiency, and stable laser output have been achieved. Finally, through different thin-film designs, the strain effect between thin film and heterosubstrate is significantly reduced, which facilitates the realization of high performance fiber lasers.

Wong, Chi Yan.
Thesis (Ph.D.)--Chinese University of Hong Kong, 2013.
Includes bibliographical references (leaves 134-149).
Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web.
Abstract also in Chinese.

碩士
國立臺北科技大學
光電工程系研究所
102
In this thesis, we report on the theoretical and experimental investigation of a heavily Tm3+-doped silicate fiber. This silicate gain fiber has Tm3+ concentration of 7wt.% (8.35x1020/cm3). To the best of our knowledge, it is the highest concentration in Tm3+ doped fibers.The theoretical work is based on a commercial simulation code, LiekkiTM. Through the simulation, we verify that Tm3+ doped silicate fibers are more suitable than thulium-doped silica fibers for long-wavelength ASE emission. Furthermore, the laser and amplifier performance under the 793-nm and 1567-nm cladding pump are addressed. Finally, we experimentally demonstrate the potential of watt-level fiber amplifier and relatively long-wavelength fiber amplifier using the 50-cm 7wt.% Tm3+-doped silicate fiber. The 793nm laser diode was employed in our research to gain the advantage of “two-to-one” cross relaxation effect, enabling up to 200% quantum efficiency. The experiment work was divided into two parts. First, we have successfully developed linear and ring-cavity fiber laser at 1978.4 nm and 2013 nm with the slope efficiency of 33.8% and 15.9%, respectively. Second, a 1.48-W 1985-nm fiber amplifier as well as an 18.2 dB 2013-nm fiber amplifier were successfully demonstrated.

This thesis describes the development of microstructured rare-earth-doped silica fibres for high power lasers. Motivated by the demand for increasingly higher power fibre lasers, this research aims to overcome the power scaling limits from non-linear effects in optical fibres. The project focussed on the demonstration of the first air-clad holmium-doped silica fibre laser. Novel fabrication techniques were employed to directly drill air-claddings in preforms produced with modified chemical vapour deposition. Key limitations for increasing single-mode laser output powers are the onset of non-linear effects, the coupling of pump power from high-power low-brightness sources, and poor lasing efficiency. Holmium doped fibre lasers were identified as a promising pathway for overcoming these power scaling limits due to their potential for high efficiencies and long wavelength emission in silica. Low loss high numerical aperture air-clad fibres were used to address the limited pump coupling, which is a primary restriction for power scaling of holmium-doped fibre lasers. Low dopant concentration fibres were fabricated to prevent clustering of holmium ions, which can limit the efficiency of holmium lasers. To compensate for the reduced pump absorption, small cladding to core area ratios were used. Coupling ability of the reduced pump cladding area was achieved with the low-loss high numerical aperture air-claddings. Multiple cladding geometries were fabricated and characterised to show their suitability for fibre laser operation. The highest reported numerical aperture for holmium-doped double-clad silica fibre was achieved. Air-clad holmium-doped fibre lasers, pumped with in-house developed thulium lasers, were demonstrated. Over 10 W of output power at 2.1 μm was achieved with high beam quality. Mechanical, thermal and laser transition modelling was performed to analyse the lasing results. This revealed that the reduction of fibre length through changes in cladding geometry or increased dopant concentration are critical for efficient high-power double-clad holmium doped fibre lasers. Air-clad holmium-doped fibre lasers are an attractive pathway for increasing high-power fibre laser output powers. These findings show potential for compact infra-red laser sources, short fibre length laser applications, and are a key step in the development of efficient high-power directly-diode pumped holmium-doped fibre lasers.
Thesis (Ph.D.) -- University of Adelaide, School of Physical Sciences, 2016.

博士
國立交通大學
光電工程研究所
103
In this thesis, a narrow-linewidth and wavelength-tunable optical source at C-band (1520-1560 nm) was implemented by a ring structure of fiber laser with a mode-selective and high quality factor microcavity, so-called silicon-micro-ring-resonator (SMRR). Both of continuous-wave (CW) and mode-locking sources were demonstrated experimentally and incorporated with fiber optics technology. For CW source it operates single-longitudinal-mode (SLM) with a narrow linewidth of 4 KHz that possesses the ability to achieve a low bit-error-rate (BER). A tolerable alignment device for passive packaging ease is also considered here. Hence, SMRR was integrated with two straight waveguides and an efficient grating coupler (GC) for C-band transmission that the coupling loss between fiber and SMRR is reduced to 7 dB. Meanwhile, the GC was optimized for TE-polarization that makes tunable wavelength covers the whole C-band in a bandwidth of 35.2 nm through controlling of mode retardance inside cavity. This configuration eases the alignment tolerance (± 3 um) to 2-dimensions and shows the stably lasing modes was observed over 30 minutes. For case of mode-locking source operated by method of filter-driven four wave mixing, it exhibits a linewidth of less 1 KHz. Compared with prior arts, the proposed sources exhibit an advanced results, making the combination of microcavity and fiber optics, and it would be a new kind of wide-tunable low error optical source, offering beat signal with high spectral purity and providing additional bandwidth for wavelength-division-multiplexing in wired or wireless communication systems.

碩士
逢甲大學
光電學系
106
In the thesis, in order to achieve a single longitudinal mode output with wavelength-tunable erbium-doped fiber ring laser, and according to the recent development of SOI, it is very interesting to construct a unique fiber laser with a sigma-based ring resonator. It is expected to be applied in optical communication, optical sensing, material processing, spectroscopy and instruments, medical diagnostics, and optical imaging. In the first section, we proposed a wavelength-tunable erbium-doped fiber (EDF) ring laser with stable single-longitudinal-mode (SLM) oscillation is proposed and investigated. Here, a silicon-micro-ring-resonator (SMRR) can be applied in a laser cavity for tuning wavelength in the C-band range. To complete the SLM oscillation, an unpumped EDF-based saturable absorber (SA) is used to act as ultra-narrowband filter for suppressing other oscillation modes. Additionally, the output stabilities of power and wavelength in the proposed EDF ring laser are also executed and discussed. In the second section, we propose and investigate a wavelength-switchable EDF glasses-type compound-ring (GTCR) laser with SLM oscillation. To accomplish wavelength-tunable operation, a SMRR is utilized inside the ring cavity, when the birefringent loss of EDF laser is adjusted properly. Moreover, the GTCR configuration is proposed serving as the mode-filter for suppressing the multi-longitudinal-mode (MLM) to achieve the SLM oscillation. Here, the measured linewidth of output wavelength is ~61 kHz. The output stabilities of the proposed SMRR EDF compound-ring laser are also discussed experimentally. In the third section, we proposed a wavelength-selectable EDF ring laser with stable SLM operation is proposed and investigated. To complete the wavelength tunability and SLM output, the SMRR and unpumped EDF-based SA are applied in the laser cavity. The output powers and optical signal to noise ratios (OSNRs) are observed in the ranges from 0.9 to 2.0 dBm and 25.8 to 32.3 dB, respectively, in the tuning range of 1530.54 to 1557.81 nm. The output wavelength linewidth of ~25 kHz can be also achieved. Moreover, the observed output power and wavelength fluctuations are less than 0.8 dB and 0.08 nm in an observation time of 30 minutes. Keywords: erbium-doped fiber ring laser; silicon-micro-ring-resonator; single-longitudinal-mode

碩士
國立臺北科技大學
光電工程系研究所
105
Because of the eye-safe properties and strong water absorption, 2 m mode-locked fiber laser sources are of big interest in applications of medicine, environmental sensing and materials processing. In this paper,we report on the investigation of mode-locked fiber lasers utilizing a Tm3+-doped nano-engineered yttrium–alumina(YA) silica glass fiber and semiconductor saturable absorber mirrors(SESAMs). The gain fiber, produced by Dr. M. C. Paul’s group in India, presents several benefits, especially the high efficiency and low loss. The pump source is a 1567-nm lab-made double-cladding-pumped Er3+ doped fiber laser. We study the mode-locked laser operation, laser slope efficiency, and output spectra under different reflectivities. Two types of cavity reflector are used. One in the fiber Bragg grating and the other is the fiber loop mirror. We successfully demonstrate the potential of the novel Tm3+-doped yttrium–alumina–silica fiber to produce a self-starting passively mode-locked fiber laser.

石墨烯，由單層碳原子緊密排列成蜂巢狀的晶體結構，擁有卓越的電學性能和光學性能。這些優異的性能包括：極高的電子遷移率，超寬的吸收光譜，栅電壓調控光躍遷性質，飽和吸收性質。石墨烯的獨特光學性質已經被用來製造多種高性能的光電器件，包括光電探測器， 飽和吸收器， 光調製器和四波混頻的介質。同時，石墨烯的製造工藝可以與現代半導體標準製造工藝相兼容， 加上它穩定的化學性質， 石墨烯非常有潛力在未來半導體工業發展中發揮重要作用。
單層石墨烯可以透過97.7% 垂直入射的光，吸收2.3% 左右，並且吸收的光頻非常寬。雖然對於單層碳原子結構，這個吸收率很大，但是在一些器件中，我們需要更高的光吸收率。爲了突破單層石墨烯光吸收的極限，一種可行的辦法是延長石墨烯與光相互作用的長度。將單層石墨烯轉移到長的硅波導上，可以延長石墨烯與光作用的長度。除了線性光吸收特性，石墨烯的飽和吸收特性也有廣泛的應用。很多脉衝激光發生器是利用被動鎖模的原理，即激光器中的飽和吸收器將連續的光波轉變成頻率固定的脉衝。石墨烯已經被證明是恢復速度快、調製範圍大的飽和吸收器。 但是，石墨烯和硅波導結合作為飽和吸收器的特性和它們的應用還從來沒有被研究過。
在論文中，我們研究了石墨烯轉移到硅波導后的線形光學性質和飽和吸收特性。首先我們討論了石墨烯轉移的方法，然後我們通過實驗調查了石墨烯在貴波導上的線形光學性質和飽和吸收特性。爲了研究石墨烯/硅波導在被動鎖模光纖激光器中的作用，我們利用石墨烯/硅波導作為飽和吸收器製造了一個光纖激光器。之後，通過在激光腔體中加入可调滤波器， 我們用成功的演示了波長可調製被動鎖模光纖激光器。
多脉衝激光光源在光纖通信，測量學和光學器件性能鑒定中有重要作用。所以研究緊湊、穩定並且價格實惠的多脉衝鎖模激光器非常有意義。爲了實現多脉衝鎖模光纖激光器，我們將硅基濾波器和石墨烯/硅波導集成在一起. 在論文中，我們設計并優化了能被應用於多脉衝鎖模激光器的寬帶寬濾波器凹凸光栅。
Graphene, a single 2D sheet of carbon atoms arranged in a honeycomb lattice, has superior electrical and optical properties including extremely high charge-carrier mobility, broadband optical absorption, gate-variable optical transitions and saturable absorptions. Its unique optical properties have led to a range of promising optoelectronic devices, such as photo detectors, saturable absorbers, optical modulators and nonlinear media for four-wave mixing. Graphene’s complementary metal-oxide-semiconductor (CMOS) integration processes at wafer scale and its electrochemical stability make it a promising candidate for post CMOS electronics.
Monolayer grapheme transmits 97.7% of the normal incident light and absorbs 2.3%, independent of wavelength. In order to overcome the challenge of limited absorption of a monolayer and better exploit graphene optical properties, a long interaction length is needed. By integrating graphene directly on top of silicon waveguides, longer light/graphene interactions can be achieved. In addition to the linear optical properties of the graphene, its saturable absorption also finds useful applications. Many ultra-short pulse lasers are based on passive mode-locking, where a saturable absorber turns continuous wave output of the laser into a train of optical pulses. And graphene has been shown to make an excellent saturable absorber. However, the saturable absorption behavior of graphene-silicon wavguides and their applications have never been studied.
In this thesis, the linear and saturable absorption of monolayer graphene films transferred onto silicon waveguide are investigated. The transfer process of monolayer graphene to silicon waveguides is studied and linear and saturable absorption measurements are carried out. To investigate applications of graphene-silicon waveguides, a passive mode-lock fiber lasers in which graphene-silicon waveguides act as saturable absorbers to mode-lock pulses is constructed. By adding a tunable filter in cavity, a tunable mode-locked fiber laser based on graphene-silicon waveguide is demonstrated.
Multi-wavelength pulse sources are important for applications including optical fiber communication, instrumentation, and photonic component characterization. The availability of compact, reliable and cost effective multi-wavelength mode-locked lasers is of great importance. We also hope to build multiwavelength mode-locked fiber lasers by integrating CWDM silicon filters with graphene-silicon waveguides. The design process and optimization of a silicon filter called echelle grating is demonstrated.
Detailed summary in vernacular field only.
Detailed summary in vernacular field only.
Detailed summary in vernacular field only.
Detailed summary in vernacular field only.
Shi, Zerui.
Thesis (M.Phil.)--Chinese University of Hong Kong, 2013.
Includes bibliographical references.
Abstracts also in Chinese.
Chapter Chapter 1: --- Introduction --- p.1
Chapter 1.1 --- Photonic Integrated Circuit (PIC) --- p.1
Chapter 1.2 --- Silicon on Insulator (SOI) Photonics --- p.3
Chapter 1.2.1 --- SOI Waveguides --- p.5
Chapter 1.2.2 --- SOI Waveguide Based Wavelength Division Multiplexing --- p.6
Chapter 1.3 --- Graphene Photonics --- p.9
Chapter 1.3.1 --- Band Structure of Monolayer Graphene --- p.9
Chapter 1.3.2 --- Optical Absorption of Graphene --- p.13
Chapter 1.3.3 --- Graphene Based Passive Mode-Locked Fiber Lasers --- p.18
Chapter 1.4 --- Motivation --- p.22
Chapter 1.5 --- Thesis Outline --- p.23
Chapter 1.6 --- Reference --- p.24
Chapter Chapter 2: --- Optical Properties of Graphene-Silicon Waveguides --- p.27
Chapter 2.1 --- Fabrication and Transfer Process of Graphene-Silicon Waveguides --- p.28
Chapter 2.1.1 --- Fabrication of SOI Waveguides --- p.28
Chapter 2.1.2 --- Transfer Process of Monolayer Graphene onto SOI Waveguides --- p.29
Chapter 2.2 --- Linear Optical Absorption of Graphene-Silicon Waveguides --- p.35
Chapter 2.2.1 --- Introduction to Photoexcitation in Monolayer Graphene --- p.35
Chapter 2.2.2 --- Experimental Results of Linear Absorption --- p.37
Chapter 2.3 --- In-Plane Saturable Absorption of Graphene-Silicon Waveguides --- p.38
Chapter 2.3.1 --- Experimental Result of In-Plane Saturable Absorption of Graphene-Silicon Waveguides --- p.39
Chapter 2.3.2 --- Mechanism of Saturable Absorption of Graphene-Silicon Waveguides --- p.42
Chapter 2.4 --- Summary --- p.44
Chapter 2.5 --- Reference --- p.45
Chapter Chapter 3: --- Hybrid Graphene-Silicon Waveguides Based Mode-Locked Fiber Lasers --- p.47
Chapter 3.1 --- Background of Graphene Based Mode-Locked Fiber Lasers --- p.47
Chapter 3.1.1 --- Passive Mode-Locked Lasers Fundamentals --- p.47
Chapter 3.1.2 --- Review of Recent Works of Graphene Based Mode-Locked Fiber Lasers . --- p.52
Chapter 3.2 --- Hybrid Graphene-Silicon Waveguides Based Mode-Locked Fiber Lasers --- p.55
Chapter 3.2.1 --- Experimental Set Up and Results --- p.55
Chapter 3.2.2 --- Discussion --- p.59
Chapter 3.3 --- Tunable Graphene-Silicon Waveguides Based Mode-Locked Fiber Lasers --- p.62
Chapter 3.4 --- Summary --- p.66
Chapter 3.5 --- Reference --- p.66
Chapter Chapter 4: --- Conclusion and Future Work --- p.68
Chapter 4.1 --- Conclusion --- p.68
Chapter 4.2 --- Future Work --- p.69
Chapter 4.2.1 --- Design and Simulation Results of Echelle Grating --- p.69
Chapter 4.2.2 --- Optimization and Experiment Results of Echelle Gratings --- p.77
Chapter 4.2.3 --- Integration of Echelle Grating with SOI Waveguides --- p.82
Chapter 4.3 --- Summary --- p.84
Chapter 4.4 --- Reference --- p.85
Chapter APPENDIX A: --- PUBLICATION LIST --- p.86
Chapter APPENDIX B: --- LIST OF FIGURES --- p.87
Chapter APPENDIX C: --- LIST OF TABLES --- p.91
Chapter APPENDIX D: --- atlab Code of Simulation of Echelle Grating --- p.92

碩士
國立成功大學
光電科學與工程研究所
97
In this paper, we divided the research of fiber lasers into two parts. First, in fiber lasers, we solved the damage problem present at the output facet in high-peak power laser systems. Unlike other approaches, such as the use of a large core fiber, which would produce multimode laser output, or the use of fusion-splicing coreless end caps to increase the spot size at the silica-air interface, which would limit the allowable bend radius of the fiber, in this paper, we bonded an optical flat at the fiber exit facet to decrease intensity and to maintain good beam quality with a matched refraction index of the bond. We also showed that the output power efficiency through the bond could reach up to 96 %. The bond could increase the reliability of a high-peak power fiber laser demonstrated beyond 1 kW with a 70 nanosecond pulse width and a repetition rate of 80 kHz. Secondly, we extended the application of the bonding process to replace costly Fiber Bragg Grating (FBG) with the optical filter by a silicate bonding process. We set up a simple fiber laser system with the optical filter and showed the transmission efficiency of the filter could reach up to 88 % and operated the bond in the CW fiber laser system to produce 3.17 W laser power at 1.1 μm. The low manufacturing cost and good temperature stability made the optical filter an excellent candidate for FBG.