Dissertations / Theses on the topic 'Ultrafast microscopy'
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Li, Jing. "Ultrafast thermoreflectance microscopy." Thesis, Boston University, 2013. https://hdl.handle.net/2144/11118.
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Thesis (Ph.D.)--Boston UniversityAs electronic and photonic devices shrink to the nanoscale, heat dissipation becomes the bottleneck for performance. As a result, understanding and controlling nanoscale thermal transport in thin films and across interfaces is a critical issue requiring new experimental tools. In this thesis, the development of an ultrafast thermoreflectance microscope for high resolution thermal property imaging is described. It can function as a time domain thermoreflectance (TDTR) or frequency domain thermoreflectance (FDTR) system. Design and implementation of the optical system will be introduced in detail. A thermal model derived from heat transfer theory is used to analyze the experimental data and obtain quantitative property maps for bulk and thin-film samples. The system is used to obtain temperature dependent thermal properties of single crystal diamond and thin film VO2, as well as thermal property maps of several thin film samples.
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Block, Alexander. "Quantifying nanoscale carrier diffusion with ultrafast optical and photocurrent microscopy." Doctoral thesis, Universitat Politècnica de Catalunya, 2019. http://hdl.handle.net/10803/668392.
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Heat transport in solids is one of the oldest problems in physics, dating back to the earliest formulations of thermodynamics. The classical laws of heat conduction are valid as long as the observed time and length scales are larger than the relaxation time and mean free path of the underlying microscopic heat carriers, such as electrons and phonons. With the advent of ultrafast lasers and nanoscale systems these regimes can now be surpassed and new refined models of heat transport are needed. In particular, the interaction of ultrashort light pulses with matter can excite electrons to high temperatures, leading to a local non-equilibrium of electrons and phonons. Under these conditions, also the transport properties of the carriers are altered.
So far, these effects have typically been studied in the time domain. The cooling of photo-excited hot electrons has been studied both in metals as well as novel 2D materials, such as graphene. However, due to a lack of spatio-temporal resolution, it has not been possible to distinguish the effects of hot-electron diffusion from other cooling mechanisms, such as electron-phonon coupling.
In this thesis, I directly track such ultrafast heat and carrier diffusion in space and time with ultrafast microscopy. By using the recently developed technique of probe-beam-scanning transient-absorption microscopy on thin gold films I directly resolve, for the first time, a transition from hot-electron diffusion to phonon-limited diffusion on the picosecond timescale. I support the understanding of these complex dynamics by theoretical modeling of the thermo-optical response based on a two-temperature model.
I apply the same technique to study hot carrier diffusion in atomically thin monolayer graphene. By comparing differently prepared samples, I study the strong influence of external parameters, such as production type, substrate, and environment on carrier diffusion.
Finally, I study hot carrier diffusion in exfoliated and encapsulated graphene devices with a novel technique of ultrafast spatio-temporal photocurrent microscopy based on the photothermoelectric effect. I extract diffusion dynamics for electrically characterized samples with the help of theoretical spatio-temporal modeling, thereby testing the fundamental relationship between electrical and thermal carrier transport.
The precise quantification of ultrafast and nanoscale carrier transport with these state-of-the-art techniques leads to a broader understanding of non-equilibrium dynamics and could ultimately help the design, optimization, and heat management of the next generation of ultra-compact (opto-) electronic devices, such as solar cells, photodetectors, or integrated circuits.El transporte de calor en sólidos es uno de los problemas más antiguos de la física, que se remonta a las primeras formulaciones de la termodinámica. Las leyes clásicas de la conducción de calor son válidas cuando las escalas de tiempo y longitud observadas sean mayores que el tiempo de relajación y la trayectoria libre media de los portadores de calor microscópicos subyacentes, como los electrones y los fonones. Con la llegada de los láseres ultrarrápidos y los sistemas a nanoescala, estos regímenes ahora pueden superarse por lo cual se necesitan nuevos modelos refinados de transporte de calor. En particular, la interacción de pulsos de luz ultracortos con la materia puede excitar electrones a altas temperaturas, lo que lleva a un desequilibrio local de electrones y fonones. En estas condiciones, también se modifican las propiedades de transporte de los portadores de calor. Hasta ahora, estos efectos han sido típicamente estudiados en el dominio del tiempo. El enfriamiento de electrones calientes fotoexcitados se ha estudiado tanto en metales como en nuevos materiales bidimensionales, como el grafeno. Sin embargo, debido a la falta de resolución espacio-temporal, no ha sido posible distinguir los efectos de la difusión de electrones calientes de otros mecanismos de enfriamiento, como el acoplamiento de electrones y fonones. En esta tesis, hago un seguimiento directo de la difusión del calor y sus portadores en el espacio y el tiempo con microscopía ultrarrápida. Al utilizar la técnica recientemente desarrollada de microscopía de absorción transitoria con escaneo de sonda en películas de oro delgadas, resuelvo directamente, por primera vez, una transición de la difusión de electrones calientes a la difusión limitada por fonones en la escala de tiempo de picosegundos. Apoyo la comprensión de estas dinámicas complejas mediante el modelado teórico de la respuesta termo-óptica basada en un modelo de dos temperaturas. Aplico la misma técnica para estudiar la difusión de portadores calientes en una capa de grafeno atómicamente delgado. Al comparar muestras preparadas de manera diferente, estudio la fuerte influencia de los parámetros externos, como el tipo de producción, el sustrato y el entorno sobre la difusión del portador. Finalmente, estudio la difusión de portadores en dispositivos de grafeno exfoliados y encapsulados con una técnica novedosa de microscopía de fotocorriente espacio-temporal ultrarrápida basada en el efecto fototermoeléctrico. Extraigo dinámicas de difusión para muestras caracterizadas eléctricamente con la ayuda del modelado espacio-temporal teórico, probando así la relación fundamental entre el transporte eléctrico y térmico. La cuantificación precisa del transporte de los portadores ultrarrápido y a nanoescala con estas técnicas de vanguardia lleva a una comprensión más amplia de la dinámica del no equilibrio y podría, en última instancia, ayudar al diseño, la optimización y la gestión del calor de la próxima generación de dispositivos (opto-)electrónicos ultracompactos, como células solares, fotodetectores o circuitos integrados.
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Wong, Tsz-wai Terence, and 黃子維. "Optical time-stretch microscopy: a new tool for ultrafast and high-throughput cell imaging." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2013. http://hub.hku.hk/bib/B5066234X.
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The exponential expansion in the field of biophotonics over the past half-century has been leading to ubiquitous basic science investigations, ranging from single cell to brain networking analysis. There is also one biophotonics technology used in clinic, which is optical coherence tomography, mostly for high-speed and high-resolution endoscopy. To keep up such momentum, new biophotonics technologies should be aiming at improving either the spatial resolution or temporal resolution of optical imaging. To this end, this thesis will address a new imaging technique which has an ultra-high temporal resolution. The applications and its cost-effective implementations will also be encompassed.
In the first part, I will introduce an entirely new optical imaging modality coined as optical time-stretch microscopy. This technology allows ultra-fast real-time imaging capability with an unprecedented line-scan rate (~10 million frames per second). This ultrafast microscope is renowned as the world’s fastest camera. However, this imaging system is previously not specially designed for biophotonics applications. Through the endeavors of our group, we are able to demonstrate this optical time-stretch microscopy for biomedical applications with less biomolecules absorption and higher diffraction limited resolution (<2 μm). This ultrafast imaging technique is particularly useful for high-throughput and high-accuracy cells/drugs screening applications, such as imaging flow cytometry and emulsion encapsulated drugs imaging.
In the second part, two cost-effective approaches for implementing optical time-stretch confocal microscopy are discussed in details. We experimentally demonstrate that even if we employ the two cost-effective approaches simultaneously, the images share comparable image quality to that of captured by costly specialty 1μm fiber and high-speed ( >16 GHz bandwidth) digitizer. In other words, the cost is drastically reduced while we can preserve similar image quality.
At the end, I will be wrapping up my thesis by concluding all my work done and forecasting the future challenges concerning the development of optical time-stretch microscopy. In particular, three different research directions are discussed.published_or_final_version
Electrical and Electronic Engineering
Master
Master of Philosophy
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Bücker, Kerstin. "Characterization of pico- and nanosecond electron pulses in ultrafast transmission electron microscopy." Thesis, Strasbourg, 2017. http://www.theses.fr/2017STRAE014/document.
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Cette thèse présente une étude des impulsions électroniques ultra-brèves en utilisant le nouveau microscope électronique en transmission ultrarapide (UTEM) à Strasbourg. La première partie porte sur le mode d’opération stroboscopique, basé sur l’utilisation d’un train d’impulsions d’électrons de l’ordre de la picoseconde pour l’étude des phénomènes réversibles ultrarapides. L’étude paramétrique effectuée a permis de révéler les dynamiques fondamentales des impulsions électroniques. Des mécanismes inconnus jusqu’alors et décisifs dans les caractéristiques des impulsions ont été dévoilés. Il s’agit des effets de trajectoire, qui limitent la résolution temporelle, et du filtrage chromatique, qui impacte la distribution en énergie et l’intensité du signal. Ces connaissances permettent aujourd’hui un paramétrage affiné de l’UTEM de manière à satisfaire les divers besoins expérimentaux. La deuxième partie concerne l’installation du mode d’opération complémentaire : le mode « singel-shot ». Ce mode fait appel à une impulsion unique d’intensité élevé et d’une durée de l’ordre de la nanoseconde pour l’étude des phénomènes irréversibles. L’UTEM de Strasbourg étant le premier instrument single-shot équipé d’un spectromètre de perte d’énergie des électrons (EELS), l’influence de l’aberration chromatique a pu été étudiée en détail. Elle s’est dévoilée être une limitation majeure pour la résolution en imagerie, nécessitant d’ajuster le bon compromis avec l’aberration sphérique d’une part et l’intensité du signal d’autre part. Enfin, la faisabilité de mener des études en EELS ultrarapide avec une seule impulsion nanoseconde a pu être démontrée, ceci constituant une première mondiale. Ce résultat très prometteur ouvre un tout nouveau domaine d’expériences résolu en tempsThis thesis presents a study of ultrashort electron pulses by using the new ultrafast transmission electron microscope (UTEM) in Strasbourg. The first part focuses on the stroboscopic operation mode which works with trains of picosecond multi-electron pulses in order to study ultrafast, reversible processes. A detailed parametric study was carried out, revealing fundamental principles of electron pulse dynamics. New mechanisms were unveiled which define the pulse characteristics. These are trajectory effects, limiting the temporal resolution, and chromatic filtering, which acts on the energy distribution and signal intensity. Guidelines can be given for optimum operation conditions adapted to different experimental requirements. The second part starts with the setup of the single-shot operation mode, based on intense nanosecond electron pulses for the investigation of irreversible processes. Having the first ns-UTEM equipped with an electron energy loss spectrometer, the influence of chromatic aberration was studied and found to be a major limitation in imaging. It has to be traded off with spherical aberration and signal intensity. For the first time, the feasibility of core-loss EELS with one unique ns-electron pulse is demonstrated. This opens a new field of time-resolved experiments
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Danz, Thomas Christian [Verfasser]. "Ultrafast transmission electron microscopy of a structural phase transition / Thomas Christian Danz." Göttingen : Niedersächsische Staats- und Universitätsbibliothek Göttingen, 2021. http://d-nb.info/1239061234/34.
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Ge, Xiaowei. "Nonlinear Microscopy Based on Femtosecond Fiber Laser." University of Dayton / OhioLINK, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=dayton1556914609069399.
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Barlow, Aaron M. "Spectral Distortions & Enhancements In Coherent Anti-Stokes Raman Scattering Hyperspectroscopy." Thesis, Université d'Ottawa / University of Ottawa, 2015. http://hdl.handle.net/10393/32388.
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Coherent anti-Stokes Raman scattering microscopy is a versatile technique for label-free imaging and spectroscopy of systems of biophysical interest. Due to the coherent nature of the generated signals, CARS images and spectra can often be difficult to interpret. In this thesis, we document how distortions and enhancements can be produced in CARS hyperspectroscopy as a result of the instrument, geometrical optical effects, or unique molecular states, and discuss how these effects may be suppressed or exploited in various CARS applications.
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Ganz, Thomas. "Supercontinuum generation by chirped pulse compression for ultrafast spectroscopy and broadband near-field microscopy." Diss., lmu, 2011. http://nbn-resolving.de/urn:nbn:de:bvb:19-148551.
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Ciesielski, Richard [Verfasser], and Achim [Akademischer Betreuer] Hartschuh. "Ultrafast dynamics in single nanostructures investigated by pulse shaping microscopy / Richard Ciesielski. Betreuer: Achim Hartschuh." München : Universitätsbibliothek der Ludwig-Maximilians-Universität, 2016. http://d-nb.info/1111505330/34.
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Chung, Hsiang-Yu [Verfasser], and Franz X. [Akademischer Betreuer] Kärtner. "Advanced fiber-optic ultrafast laser sources for multiphoton microscopy / Hsiang-Yu Chung ; Betreuer: Franz X. Kärtner." Hamburg : Staats- und Universitätsbibliothek Hamburg, 2020. http://d-nb.info/1213901227/34.
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Keunecke, Marius [Verfasser]. "Ultrafast electron dynamics measured with a novel time-resolved high-repetition rate momentum microscopy setup / Marius Keunecke." Göttingen : Niedersächsische Staats- und Universitätsbibliothek Göttingen, 2021. http://d-nb.info/1230628428/34.
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Caruso, Giuseppe Mario. "Development of a coherent ultrafast transmission electron microscope based on a laser-driven cold field emission source." Thesis, Toulouse 3, 2019. http://www.theses.fr/2019TOU30140.
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L'étude de la physique des systèmes à l'échelle nanométrique nécessite idéalement une résolution spatiale atomique et une résolution temporelle de l'ordre de la femtoseconde. La microscopie électronique en transmission ultra-rapide (UTEM), qui combine une résolution temporelle inférieure à la picoseconde et une résolution spatiale nanométrique, est récemment apparue comme un outil unique doté de résolutions spatio-temporelles sans précédent. Cependant, les performances des premiers UTEMs étaient limitées par la brillance des photocathodes utilisées comme source d'électrons ultra-rapide. Dans ce contexte, il a été vite réalisé que les UTEMs utilisant des sources d'électrons déclenchées par laser et basées sur des pointes métalliques comme émetteur, permettraient de dépasser cette limitation. L'objectif de cette thèse est de décrire le développement d'un microscope électronique en transmission ultra-rapide basé sur ce type de source dites " source à émission de champ froide ", pouvant fonctionner en mode continu ou ultra-rapide. L'émission d'électrons d'une nanopointe de tungstène est déclenchée par des impulsions laser femtosecondes, qui sont fortement focalisées par des composants optiques insérés proche de la cathode. La brillance mesurée est la plus grande mesurée à ce jour dans un UTEM. En associant cette nouvelle source de brillance élevée à un système d'injection/cathodoluminescence composé d'un miroir parabolique installé au-dessus du porte-échantillon, l'UTEM peut être utilisé pour réaliser des expériences TEM-pompe-sonde ultra-rapides résolues dans le temps. Les possibilités d'un tel instrument pour l'imagerie ultra-rapide, la diffraction, l'holographie électronique et la spectroscopie sont présentées. Une attention particulière a été accordée aux applications en nano-optique. La spectroscopie électronique de gain d'énergie (EEGS) permet notamment d'étudier les excitations optiques de nano-systèmes à travers les modifications du spectre d'énergie des électrons. La possibilité de synchroniser facilement les impulsions d'électrons libres ultra-courts avec l'excitation optique de l'échantillon dans les UTEM est essentielle pour l'observation d'interactions électron/photon fortement non linéaires. Ces expériences nous ont permis de caractériser les propriétés spectro-temporelles du faisceau d'électrons ultra-courts. La dernière partie propose une discussion des premières expériences d'holographie électronique hors-axe réalisées avec des impulsions électroniques ultra-rapides. En effet, la dose d'électrons dans le plan de l'échantillon étant considérablement réduite en raison du faible taux de répétition du train d'impulsions électronique, les hologrammes ultra-rapides sont obtenus dans des conditions dites " low dose " complexes. En conséquence, les paramètres expérimentaux couramment utilisés pour l'acquisition d'hologrammes avec des TEM conventionnels ne peuvent pas être directement utilisés en mode ultra-rapide. Des études expérimentales ont été réalisées pour déterminer les conditions optimales pour l'holographie électronique hors-axe ultra-rapide. L'influence de la dose, la longueur de cohérence de la source, les conditions d'illumination et les instabilités de l'instrument ont été systématiquement prises en compteThe investigation of the physics of nanoscale systems ideally requires atomic spatial resolution and femtosecond time-resolution. Ultrafast Transmission Electron Microscopy (UTEM) combining subpicosecond temporal resolution and nanometer spatial resolution has recently emerged as a unique tool with unprecedented spatio-temporal resolutions. However, the performances of the first UTEMs were limited by the brightness of the photocathodes used as ultrafast electron source. In this context, it was soon realized that UTEMs relying on laser-driven electron sources based on nanoscale emitters would overcome this limitation. The aim of this thesis is to report the development of an ultrafast Transmission Electron Microscope based on a cold field emission source, which can operate either in DC or ultrafast mode. Electron emission from a tungsten nanotip is triggered by femtosecond laser pulses, which are tightly focused by optical components integrated inside a cold-field emission source close to the cathode. The measured brightness is the largest reported so far for UTEMs. Combining this new high brightness source with an injection/Cathodoluminescence system, composed of a parabolic mirror placed above the sample holder, the UTEM can be used to perform time-resolved ultrafast pump-probe TEM experiments. The possibilities of such an instrument for ultrafast imaging, diffraction, electron holography and spectroscopy are presented. Particular attention has been paid on applications in nano-optics. In particular, Electron Energy Gain Spectroscopy (EEGS) allows to investigate the optical excitations of nanosystems in the energy domain. The ability to easily synchronize ultrashort free electron pulses with the optical excitation of the sample in UTEMs is essential for the observation of strongly nonlinear electron/photon interactions. These experiments will enable us to characterize the spectro-temporal properties of the ultrashort electron beam. Off-axis electron holography performed with ultrafast electron pulses are finally discussed. The electron dose in the specimen plane is considerably reduced due to the low repetition rate of the electron pulse train. This peculiar property of ultrafast FE-TEMs implies that ultrafast holograms are acquired in low-dose-like conditions. As a consequence, the experimental parameters commonly used for the acquisition of off-axis electron holograms with conventional TEMs cannot be directly implemented in the ultrafast mode. Experimental studies were performed to find the optimum conditions for ultrafast off-axis electron holography. Influence of the dose, the coherence length of the source, the illumination condition and the instrument instabilities have been addressed
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Khalil, Lama. "Ultrafast study of Dirac fermions in topological insulators." Thesis, Université Paris-Saclay (ComUE), 2018. http://www.theses.fr/2018SACLS344/document.
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Cette thèse présente une étude expérimentale des propriétés électroniques de deux matériaux topologiques, notamment l’isolant topologique tridimensionnel irradié Bi₂Te₃ et le super-réseau topologique naturel Sb₂Te. Les deux systèmes ont été étudiés par des techniques basées sur la spectroscopie de photoémission. Les composés Bi₂Te₃ ont été irradiés par des faisceaux d’électrons de haute énergie. L’irradiation avec des faisceaux d’électrons est une approche très prometteuse pour réaliser des matériaux qui sont vraiment isolants dans le volume, afin de mettre en évidence le transport quantique dans les états de surface protégés. En étudiant une série d’échantillons de Bi₂Te₃ par la technique de spectroscopie de photoémission résolue en temps et en angle (trARPES), nous montrons que les propriétés topologiques des états de surface de Dirac sont conservées après irradiation électronique, mais leurs dynamiques ultra-rapides de relaxation sont très sensibles aux modifications reliées aux propriétés du volume. De plus, nous avons étudié la structure électronique des bandes occupées et inoccupées du Sb₂Te. En utilisant la microscopie de photoémission d’électrons à balayage (SPEM), nous avons constamment trouvé diverses régions non équivalentes sur la même surface après avoir clivé plusieurs monocristaux de Sb₂Te. Nous avons pu identifier trois terminaisons distinctes caractérisées par différents rapports stœchiométriques de surface Sb/Te et possédant des différences claires dans leurs structures de bandes. Pour la terminaison dominante riche en tellure, nous avons également fourni une observation directe des états électroniques excités et de leurs dynamiques de relaxation en ayant recours à la technique trARPES. Nos résultats indiquent clairement que la structure électronique de surface est fortement affectée par les propriétés du volume du super-réseau. Par conséquent, pour les deux systèmes, nous montrons que la structure électronique de surface est absolument connectée aux propriétés du volumeThis thesis presents an experimental study of the electronic properties of two topological materials, namely, the irradiated three-dimensional topological insulator Bi₂Te₃ and the natural topological superlattice phase Sb₂Te. Both systems were investigated by techniques based on photoemission spectroscopy. The Bi₂Te₃ compounds have been irradiated by high-energy electron beams. Irradiation with electron beams is a very promising approach to realize materials that are really insulating in the bulk, in order to emphasize the quantum transport in the protected surface states. By studying a series of samples of Bi₂Te₃ using time- and angle-resolved photoemission spectroscopy (trARPES) we show that, while the topological properties of the Dirac surface states are preserved after electron irradiation, their ultrafast relaxation dynamics are very sensitive to the related modifications of the bulk properties. Furthermore, we have studied the occupied and unoccupied electronic band structure of Sb₂Te. Using scanning photoemission microscopy (SPEM), we have consistently found various nonequivalent regions on the same surface after cleaving several Sb₂Te single crystals. We were able to identify three distinct terminations characterized by different Sb/Te surface stoichiometric ratios and with clear differences in their band structure. For the dominating Te-rich termination, we also provided a direct observation of the excited electronic states and of their relaxation dynamics by means of trARPES. Our results clearly indicate that the surface electronic structure is strongly affected by the bulk properties of the superlattice. Therefore, for both systems, we show that the surface electronic structure is absolutely connected to the bulk properties
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Kolodziej, Charles. "Laser Spectroscopic Studies of Ultrafast Charge Transfer Processes in Solar Cell Materials." Case Western Reserve University School of Graduate Studies / OhioLINK, 2020. http://rave.ohiolink.edu/etdc/view?acc_num=case1586371698913592.
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Ganz, Thomas [Verfasser], and Ferenc [Akademischer Betreuer] Krausz. "Supercontinuum generation by chirped pulse compression for ultrafast spectroscopy and broadband near-field microscopy / Thomas Ganz. Betreuer: Ferenc Krausz." München : Universitätsbibliothek der Ludwig-Maximilians-Universität, 2011. http://d-nb.info/102665355X/34.
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Rubiano, da Silva Nara [Verfasser], Claus [Akademischer Betreuer] Ropers, Claus [Gutachter] Ropers, and Stefan [Gutachter] Mathias. "Ultrafast Lorentz Microscopy using High-Coherence Electron Pulses / Nara Rubiano da Silva ; Gutachter: Claus Ropers, Stefan Mathias ; Betreuer: Claus Ropers." Göttingen : Niedersächsische Staats- und Universitätsbibliothek Göttingen, 2019. http://d-nb.info/1185757678/34.
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Bormann, Reiner [Verfasser], Claus [Akademischer Betreuer] Ropers, and Markus [Akademischer Betreuer] Münzenberg. "Development and characterization of an electron gun for ultrafast electron microscopy / Reiner Bormann. Betreuer: Claus Ropers. Gutachter: Claus Ropers ; Markus Münzenberg." Göttingen : Niedersächsische Staats- und Universitätsbibliothek Göttingen, 2015. http://d-nb.info/1080609954/34.
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Bormann, Reiner Verfasser], Claus [Akademischer Betreuer] Ropers, and Markus [Akademischer Betreuer] [Münzenberg. "Development and characterization of an electron gun for ultrafast electron microscopy / Reiner Bormann. Betreuer: Claus Ropers. Gutachter: Claus Ropers ; Markus Münzenberg." Göttingen : Niedersächsische Staats- und Universitätsbibliothek Göttingen, 2015. http://nbn-resolving.de/urn:nbn:de:gbv:7-11858/00-1735-0000-0028-867D-4-8.
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Yong, Chaw Keong. "Ultrafast carrier dynamics in organic-inorganic semiconductor nanostructures." Thesis, University of Oxford, 2012. http://ora.ox.ac.uk/objects/uuid:b2efdc6a-1531-4d3f-8af1-e3094747434c.
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This thesis is concerned with the influence of nanoscale boundaries and interfaces upon the electronic processes that occur within the inorganic semiconductors. Inorganic semiconductor nanowires and their blends with semiconducting polymers have been investigated using state-of-the-art ultrafast optical techniques to provide information on the sub-picosecond to nanosecond photoexcitation dynamics in these systems. Chapters 1 and 2 introduce the theory and background behind the work and present a literature review of previous work utilising nanowires in hybrid organic photovoltaic devices, revealing the performances to date. The experimental methods used during the thesis are detailed in Chapter 3. Chapter 4 describes the crucial roles of surface passivation on the ultrafast dynamics of exciton formation in gallium arsenide (GaAs) nanowires. By passivating the surface states of nanowires, exciton formation via the bimolecular conversion of electron-hole plasma can observed over few hundred picoseconds, in-contrast to the fast carrier trapping in 10 ps observed in the uncoated nanowires. Chapter 5 presents a novel method to passivate the surface-states of GaAs nanowires using semiconducting polymer. The carrier lifetime in the nanowires can be strongly enhanced when the ionization potential of the overcoated semiconducting polymer is smaller than the work function of the nanowires and the surface native oxide layers of nanowires are removed. Finally, Chapter 6 shows that the carrier cooling in the type-II wurtzite-zincblend InP nanowires is reduced by order-of magnitude during the spatial charge-transfer across the type-II heterojunction. The works decribed in this thesis reveals the crucial role of surface-states and bulk defects on the carrier dynamics of semiconductor nanowires. In-addition, a novel approach to passivate the surface defect states of nanowires using semiconducting polymers was developed.
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Mitchell, Claire A. "Photoporation and optical manipulation of plant and mammalian cells." Thesis, University of St Andrews, 2015. http://hdl.handle.net/10023/6328.
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Optical cell manipulation allows precise and non-invasive exploration of mammalian cell function and physiology for medical applications. Plants, however, represent a vital component of the Earth's ecosystem and the knowledge gained from using optical tools to study plant cells can help to understand and manipulate useful agricultural and ecological traits. This thesis explores the potential of several biophotonic techniques in plant cells and tissue. Laser-mediated introduction of nucleic acids and other membrane impermeable molecules into mammalian cells is an important biophotonic technique. Optical injection presents a tool to deliver dyes and drugs for diagnostics and therapy of single cells in a sterile and interactive manner. Using femtosecond laser pulses increases the tunability of multiphoton effects and confines the damage volume, providing sub-cellular precision and high viability. Extending current femtosecond photoporation knowledge to plant cells could have sociological and environmental benefits, but presents different challenges to mammalian cells. The effects of varying optical and biological parameters on optical injection of a model plant cell line were investigated. A reconfigurable optical system was designed to allow easy switching between different spatial modes and pulse durations. Varying the medium osmolarity and optoinjectant size and type affected optoinjection efficacy, allowing optimisation of optical delivery of relevant biomolecules into plant cells. Advanced optical microscopy techniques that allow imaging beyond the diffraction limit have transformed biological studies. An ultimate goal is to merge several biophotonic techniques, creating a plant cell workstation. A step towards this was demonstrated by incorporating a fibre-based optical trap into a commercial super-resolution microscope for manipulation of cells and organelles under super-resolution. As proof-of-concept, the system was used to optically induce and quantify an immunosynapse. The capacity of the super-resolution microscope to resolve structure in plant organelles in aberrating plant tissue was critically evaluated.
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Feist, Armin [Verfasser], Claus [Akademischer Betreuer] Ropers, Claus [Gutachter] Ropers, Tim [Gutachter] Salditt, and Klaus [Gutachter] Sokolowski-Tinten. "Next-Generation Ultrafast Transmission Electron Microscopy – Development and Applications / Armin Feist ; Gutachter: Claus Ropers, Tim Salditt, Klaus Sokolowski-Tinten ; Betreuer: Claus Ropers." Göttingen : Niedersächsische Staats- und Universitätsbibliothek Göttingen, 2018. http://d-nb.info/1165304872/34.
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Priebe, Katharina Elisabeth [Verfasser], Claus [Akademischer Betreuer] Ropers, Stefan [Gutachter] Mathias, and Thomas [Gutachter] Baumert. "Coherent Control and Reconstruction of Free-Electron Quantum States in Ultrafast Electron Microscopy / Katharina Elisabeth Priebe ; Gutachter: Stefan Mathias, Thomas Baumert ; Betreuer: Claus Ropers." Göttingen : Niedersächsische Staats- und Universitätsbibliothek Göttingen, 2018. http://d-nb.info/114995471X/34.
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Berberian, Delsalle Tiphaine. "Nouvelle source laser pour des applications en neuroscience." Thesis, université Paris-Saclay, 2021. http://www.theses.fr/2021UPASP011.
Full textAbstract:
Les neurosciences, dont l'objectif à terme est de guérir les maladies neurodégénératives, sont en train de vivre de grandes avancées transformationnelles. Parmi celles-ci, on note le développement de capteurs neuronaux efficaces permettant la détection de potentiels d’action individuels ainsi que l'apparition de nouveaux actuateurs optogénétiques. L'existence de sources laser femtoseconde, plus ou moins énergétiques, dans la gamme spectrale d'absorption à 2 photons de ces molécules permet une investigation tout-optique de réseaux de neurones in vivo et en 3D.Le manuscrit s'inscrit dans un projet faisant collaborer différents acteurs dans le domaine de la Recherche : le Laboratoire Charles Fabry pour l'aspect laser et l'Institut de la Vision pour la réalisation d'images biologiques inédites sur des sujets in vivo, ainsi que dans le domaine industriel : Amplitude Systèmes, leader mondial dans les lasers à fibres femtoseconde, et ALPhANOV, association à but non lucratif qui développe et intègre des systèmes optiques. Le but est de réaliser un outil permettant une activation multicellulaire en 3D suivi d’un diagnostique permettant d’analyser la réponse neuronale à l’échelle de la milliseconde. Pour cela, je présente le développement d'un laser spécifique (avec des impulsions de durée suffisamment courte et intense) permettant une excitation à 2 photons parallélisée. De plus ce laser émet dans la gamme spectrale des bio-activateurs et biocapteurs utilisés, ce qui en fait une source totalement originale.Le développement de ce laser femtoseconde à base de fibre thulium est détaillé. Ce laser dispose de deux sorties : une sortie haute cadence pour l'imagerie et une sortie haute énergie pour la photo-activation. Cette thèse comporte un volet expérimental et technologique important lié à la conception et à l’analyse de sources laser impulsionnelles. Les performances démontrées ici pour la voie haute cadence est l'émission d'une puissance de 10 W autour de 1950 nm à une cadence de 40 MHz. La voie haute énergie développée, quant à elle, a permis à démontrer la génération d'impulsions de 10 µJ autour de 1950 nm. Une fois la conversion en fréquence effectués les performances obtenues sont suffisamment prometteuses pour déclencher des premiers tests sur des échantillons biologiquesNeurosciences, whose ultimate goal is to cure neurodegenerative diseases, are undergoing major transformational advances. Among these is the development of efficient neural sensors allowing the detection of individual action potentials as well as the emergence of new optogenetic actuators. The existence of femtosecond laser sources, more or less energetic, in the 2-photon absorption spectral range of these molecules allows an all-optical investigation of neural networks in vivo and in 3D.The manuscript is part of a project involving different actors in the field of Research: the Laboratoire Charles Fabry for the laser aspect and the Institut de la Vision for the production of previously unseen biological images on subjects in vivo, as well as in the industrial field: Amplitude Systèmes, world leader in femtosecond fiber lasers, and ALPhANOV, a non-profit association which develops and integrates optical systems. The goal is to produce a tool allowing multicellular activation in 3D followed by a diagnostic allowing the analysis of the neuronal response at the millisecond scale. For this, I present the development of a specific laser (with pulses of sufficiently short and intense duration) allowing parallelized 2-photon excitation. In addition, this laser emits in the spectral range of the bio-activators and biosensors used, which makes it a completely original source.The development of this femtosecond laser based on thulium fiber is detailed. This laser has two outputs: a high speed output for imaging and a high energy output for photo-activation. This thesis includes an important experimental and technological part related to the design and analysis of pulsed laser sources. The performance demonstrated here for the high repetition rate channel is the emission of a power of 10 W around 1950 nm at a rate of 40 MHz. The high-energy channel developed, for its part, made it possible to demonstrate the generation of pulses of 10 µJ around 1950 nm. Once the frequency conversion has been carried out, the performance obtained is sufficiently promising to trigger initial tests on biological samples
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Kim, Daekeun Ph D. Massachusetts Institute of Technology. "Ultrafast optical pulse manipulation in three dimensional-resolved microscope imaging and microfabrication." Thesis, Massachusetts Institute of Technology, 2009. http://hdl.handle.net/1721.1/49759.
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Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2009.Includes bibliographical references.
The availability of lasers with femtosecond, ultrafast light pulses provides new opportunities and challenges in instrument design. This thesis addresses three aspects of utilizing ultrafast light pulses in two-photon excitation microscopy. First, optical fibers are routinely used in many optical instruments but their use in two-photon microscopy is very limited. As ultrafast light pulses propagate through conventional fiber optics, light pulses are dispersed and broadened, as a result of nonlinear interactions between light and material. Two-photon excitation efficiency is reduced with pulse broadening. The recent development of photonic crystal fibers allows unprecedented control of light properties through them. This thesis provides a thorough quantitative characterization of different conventional optical fibers and photonic crystal fibers enabling better utilization of these fibers for two-photon microscopic imaging. Second, two-photon microscopic imaging is relatively slow due to the sequential nature of raster scanning. Several groups have recently sought to overcome this limitation by developing a 3D-resolved wide-field two-photon microscope using the concept of temporal focusing that is based on manipulating the dispersion of ultrafast light pulses spatially. However, the existing temporal focusing systems have poor optical sectioning capability and, due to a shortage of illumination power, low actual frame rate. In this thesis, a comprehensive mathematical model is derived for temporal focusing two-photon microscope taking key instrument design parameters into account.
(cont.) By optimizing instrument design and the use of high two-photon cross section quantum dots, we demonstrate single quantum dot imaging at micron level resolution at video rate. Lastly, we realize that the temporal focus concept may also be used for microfabrication. A prototype three-dimensional lithographic microfabrication system is developed and micro patterning capability based on photobleaching process is demonstrated.
by Daekeun Kim.
Ph.D.
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Mishchik, Konstantin. "Ultrafast laser-induced modification of optical glasses : a spectroscopy insight into the microscopic mechanisms." Phd thesis, Université Jean Monnet - Saint-Etienne, 2012. http://tel.archives-ouvertes.fr/tel-00966418.
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Local refractive index changes (RIC) are the building blocks of laser-induced optical functions in bulk transparent materials, where the use of a fused silica as a target material plays a paramount role. Depending on the regime of laser interaction ultra-short pulses can induce positive isotropic refractive index changes (usually denoted as type I) or produce self-arranged nano-scale layered structures resulting in form birefringence (type II). In this thesis we have studied two objectives related to these material transformations. From the one side, we qualitatively determined the effects of the focused ultra-short laser pulses on the fused silica and borosilicate glasses. With the independent control of the energetic dose, pulse duration and focusing conditions, the isotropic type I and birefringent type II traces could be performed with the certain optical properties. Finally, complex polarization sensitive devices were designed and fabricated. From the other side, as these types of RIC have consequences in the functionality and the performances of 3D embedded optical devices, an investigation of the laser-induced structures is particularly useful. We applied photoluminescence and Raman microscopy (RM) to investigate defect formation and glass network reorganization paths. The proposed spectroscopy study distinguishes type I and type II regions by presence and distribution of silicon clusters and non-bridging oxygen hole centers (NBOHC). RM reveals signs of compaction of the glass network in the RIC regions. At the same time, zones with high concentration of NBOHC where no visible RIC and densification signs were detected. Assuming that these zones are precursors of permanent visible modification, we propose a scenario of cold defect-assisted densification realized in type I irradiation regime. This, thereby, revises the densification paths in fused silica
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Matos, Raimundo Duarte de Joana Cristina. "Ultrafast Nanoscale 3D Coherent X-ray Imaging." Thesis, Université Paris-Saclay (ComUE), 2019. http://www.theses.fr/2019SACLS372.
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Les techniques d'imagerie sans lentille permettent d'aller au-delà des limites inhérentes à la microscopie classique (à l'aide de lentille par exemple). La configuration d’imagerie par diffraction cohérente permet d'imager des objets noncristallins à des résolutions limitées en principe à la longueur d'onde (soit quelques dizaines de nanomètres à quelques angströms dans le domaine XUV à X, respectivement). Le travail de cette thèse a consisté à développer et améliorer, expérimentalement et numériquement, des nouvelles techniques d'imagerie 2D et 3D, de résolution nanométrique et en simple tir femtoseconde. Nous constatons cependant que les techniques d‘imagerie sans lentille peuvent être limitée par les aberrations et la cohérence partielle. Des améliorations des techniques d’holographie par correction de front d’onde et de la cohérence sont proposées. In fine, l’exploitation des propriétés de la source permet l’optimisation de la lecture des figures de diffraction ou des hologrammes afin d’obtenir une image la plus fidèle possible en un flash femtoseconde unique. En exploitant des concepts de vision machine, cette thèse a ensuite montré la possibilité d’accéder à la 3D en simple tir à partir de deux figures de diffraction X cohérente prise simultanément sur deux angles stéréo. Ceci ouvre la voie à l'exploration de la matière sur des volumes nanométriques (voxels) résolus à la femtosecondeCoherent lensless imaging techniques can break the limitations associated with conventional microscopy techniques. The configuration of coherent diffraction imaging makes it possible to image isolated non-crystalline objects with spatial resolutions limited, in principle, only by the illuminated wavelength (i.e. a few tens of nanometers to a few angstroms in the XUV and X domains, respectively). In this thesis, we develop and improve, experimentally and numerically, 2D and 3D lensless imaging techniques, for nanometric resolutions in a femtosecond single shot. Responding to the limitations of these techniques to aberrations and partial coherence, here, improvements of wavefront and spatial-coherence correction in holographic techniques are proposed. Indeed, the exploitation of the source properties makes possible to optimise the reconstruction from diffraction patterns or holograms in order to obtain the most faithful image possible in a single femtosecond flash. By exploiting machine vision concepts, this thesis also shows the possibility of accessing 3D information in single shots, extracted from two coherent X-ray diffraction patterns, taken simultaneously from two stereo angles. This opens the way towards the exploration of matter on nanometric volumes (voxels) solved at unmatched temporal resolutions
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Mermillod-Blondin, Alexandre. "Analysis and optimization of ultrafast laser-induced bulk modifications in dielectric materials." Saint-Etienne, 2007. http://www.theses.fr/2007STET4004.
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By focusing an ultrashort pulse of light in the volume of a transparent dielectric, free carrier generation takes place via nonlinear ionization. A substantial part of the laser energy is deposited into the free carrier gas, transferred into the bulk, and a material with new optical properties emerges upon energy relaxation. Phase contrast (PCM) and optical transmission microscopy (OTM) techniques are employed to characterize the morphology of the laser-induced refractive index change in the bulk of amorphous silica and N-BK7. The experimental results are correlated with a theoretical estimation of the energy deposited in the vicinity of the focal plane based on the resolution of the nonlinear Schrödinger equation. In fused silica, the formation of a void is connected with the appearance of a high energy exposure upon nonlinear propagation. A time-resolved study of the laser generated refractive index modifications with sub-picosecond and sub-micrometer resoltion is performed. This analysis points out the importance of the thermal mechanisms and of the subsequent thermochemical transformations in laser modification of bulk dielectrics. By using an adaptative pulse shaping apparatus, we demonstrate that optical structures that do not normally appear in standard ultrafast irradiation conditions can be generated. In particular, we report the onset of large positive refractive index regions in BK7. Finally, the flexibility offered by temporal pulse manipulation is exploited for microprocessing purposes. We demonstrate writing of embedded waveguiding structures at optical frequencies in the bulk of BK7En focalisant une impulsion lumineuse ultra brève dans la masse d'un matériau diélectrique transparent, un mécanisme d'ionisation non-linéaire peut conduire à la création de porteurs libres. L'énergie lumineuse est alors efficacement déposée. Après relaxation de l'énergie, un matériau avec de nouvelles propriétés optiques est obtenu. Les propriétés optiques de ce matériau transformé ainsi que la morphologie de la zone altérée sont caractérisés en microscopie à contraste de phase et en microscopie optique classique. Les échantillons étudiés sont principalement la silice pure et le N-BK7. Les observations expérimentales sont corrélées avec une estimation théorique de la densité d'énergie déposée obtenue en résolvant l'équation de Schrödinger non-linéaire. Dans la silice pure, l'apparition d'une micro-cavité est ainsi associée à une région de forte exposition à l'énergie lumineuse. Une étude basée sur un dispositif de microscopie de phase et de microscopie classique caractérisée par une résolution spatiale submicrométrique et une résolution temporelle subpicoseconde est également présentée. Cette analyse révèle l'importance des phénomènes thermiques et des effets thermomécaniques. En optimisant la forme temporelle de l'impulsion, nous démontrons la possibilité de conduire le matériau de manière permanente dans des états inaccessibles lorsqu'on se limite à une irradiation ultra brève classique. En particulier, nous montrons l'existence de régions de densités élevées dans le BK7 après irradiation. Enfin, la souplesse offerte par la mise en forme temporelle est employée afin de réaliser l'écriture de guides d'ondes enterrés dans le BK7
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Ayche, Kenza. "Propriétés mécaniques et structurales d'encapsulants polymères utilisés en microélectronique : effet de la température et de l'humidité." Thesis, Le Mans, 2017. http://www.theses.fr/2017LEMA1005/document.
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L’engouement mondial pour les appareils nomades et la course à la sobriété énergétique font de la diminution de la taille des systèmes microélectroniques (MEMS) un enjeu majeur pour les prochaines années. Les micro batteries au lithium sont aujourd'hui le moyen le plus efficace pour stocker et alimenter des dispositifs avec une très forte densité énergétique. Les incorporer dans des cartes de crédit comportant un écran et des touches intégrés est l’un des défis que relèvent les multinationales comme ST Micro Electronics. Ces micro batteries contiennent cependant du lithium métallique qui peut s'avérer très dangereux quand il est en contact avec de l’eau ou de l’air humide. Ainsi, afin de protéger les composants à une exposition à l’humidité, une encapsulation de l’ensemble de la batterie est nécessaire. L'encapsulation polymère a l’avantage, comparativement à d’autres matériaux, de présenter un faible coût de mise en forme et un faible poids. Cependant, de tels systèmes d'encapsulation sont aujourd'hui insuffisants pour garantir une durée de vie de plusieurs années des composants car en présence d’humidité ou d’une variation de température importante la tenue mécanique des assemblages peut être fragilisée. L'objectif de la thèse est donc de réaliser et d'étudier le comportement mécanique et structural d’assemblage de couches minces de polymères et de métaux en température et en humidité. Deux types de polymères ont été choisis pour ce projet :1. Le chlorure de polyvinylidène (PVDC), un polymère commercial très utilisé pour ses bonnes propriétés barrières à l'eau 2. Un oligomère acrylate reticulable par voie thermique et UV synthétisé au sein de l'IMMMThe increasing number of mobile devices and the race to energy sobriety make the decrease of the size of microelectronic systems (MEMS) a major challenge. Today, Lithium micro batteries are currently the best solution for high-power-and-energy applications. Incorporate them into credit cards containing a screen or associate them to electronic sensors for the supervision is the challenge which raises international companies such as ST Microelectronics. However, these micro batteries contain some lithium metal which can be dangerous if the metallic lithium is in contact with water or humid air. In addition, the substance can spontaneously ignite in the contact of the humidity. So, in order to avoid the problems of safety, we absolutely have to protect the lithium contained in our micro batteries using an encapsulation layer. Polymeric encapsulation has the advantage, compared with other materials (ceramic, metal), to present a moderate cost of shaping and a low weight. However, such systems of encapsulation are today insufficient to guarantee a satisfactory life cycle of components. Indeed, in the presence of humidity or of a too important temperature variation, the mechanical assemblies can be weakened and engender an irreparable break. The objective of the thesis is therefore to realize and study the mechanical and structural behavior of assembly of thin layers of polymers and metals in temperature and humidity.Two types of polymers were selected for this project:1. Polyvinylidene chloride (PVDC), a commercial polymer widely used for its good barrier properties to water.2. A thermally and UV-crosslinkable acrylate oligomer synthesized in the IMMM
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Shih, Sheng-Chih, and 施勝志. "The Applications of Ultrafast Laser in Microscopic Imaging：RF OBIC＆SHG Microscopy." Thesis, 2002. http://ndltd.ncl.edu.tw/handle/55135142189129102869.
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碩士國立中山大學
物理學系研究所
90
In this study，we apply the broad bandwidth and high energy pulse of ultrafast laser to experiment on RF OBIC and second harmonic generation. In this paper a novel method is presented for characterizing high frequency response and behavior of ultra high-speed photosensitive semiconductor devices and the set-up is capable of generating excitation at RF bandwidths of greater than 1.8 THz. In addition，the collagen of dentine is able to generate the second harmonic in the ultraviolet region, so we develop a high performance transmission mode laser scanning microscope for obtaining SHG images of a tooth slice. We also study wavelength dependence and polarization dependence.
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Rubiano, da Silva Nara. "Ultrafast Lorentz Microscopy using High-Coherence Electron Pulses." Doctoral thesis, 2019. http://hdl.handle.net/11858/00-1735-0000-002E-E628-A.
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Villafana, Tana Elizabeth. "Ultrafast Pump-Probe Microscopy in Cultural Heritage Research." Diss., 2015. http://hdl.handle.net/10161/9934.
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The materials and working method of a painting can reveal important information about our cultural history, as well as lend the conservator the necessary knowledge for treatment options. The removal of a cross-section sample reveals the three-dimensional (3d) structure of the painting and can be used to identify materials. However, cross-section samples are destructive and provide only local information. Nonlinear optical ultrafast pump-probe microscopy, originally developed for biomedical imaging, can provide high resolution 3d images with chemical contrast. In this dissertation, I adapt pump-probe microscopy to multiple materials and applications in cultural heritage research. Pump-probe dynamics were found to be sensitive to the ratio of the two chromophores present in the precious blue pigment lapis lazuli and its synthetic analogs, ultramarines blue and violet. Virtual pump-probe cross-sections were combined with nonlinear fluorescence contrast to study differences between the interactions of paper supports with inorganic crystalline pigments and organic dyes. Multiple early Italian paintings (The Crucifixion by Puccio Capanna, The Martyrdom of St. Alexander and The Body of Christ Supported by Angels attributed to Lorenzo Lotto) were imaged in-situ, in conjunction with traditional conservation science methods, as a part of a technical case study. Thus, pump-probe microscopy offers an important new tool for gaining fundamental insights into our cultural heritage.
Dissertation
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Peng, Wei-tung, and 彭偉棟. "Pump-Probe Based Ultrafast Time-Resolved Laser Scanning Microscopy." Thesis, 2005. http://ndltd.ncl.edu.tw/handle/92504115411109677492.
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碩士國立中山大學
光電工程研究所
93
Recently, lifetime imaging has become a subject of intensive research. Lifetime is an important parameter to understand the dynamics of targeted objects and its applications ranges from fluorescence decay of biological objects to relaxation of semiconductor materials and devices. Many methods, such as time-correlated single photon counting (TCSPC) and phase detection in frequency domain, were developed to measure the characteristic lifetime. These methods are now rather matured and widely applied in various studies. However, these methods are only effective for lifetime longer than 100 picoseconds due to the bandwidth limitation of high-speed electronics. For even faster temporal resolution, novel techniques that do not rely on high-speed electronics will be required. In this study, we are integrating an autocorrelator with a galvo-based laser scanning microscope to enable imaging with very high temporal resolution. The principle and technique of pump-probe is implemented through the autocorrelator. In this way, imaging based pump-probe measurements can be realized. Specifically, we have applied the experimental setup so developed in measuring fluorescent dyes and semiconductor devices.
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Feist, Armin. "Next-Generation Ultrafast Transmission Electron Microscopy – Development and Applications." Thesis, 2018. http://hdl.handle.net/11858/00-1735-0000-002E-E48B-B.
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Bormann, Reiner. "Development and characterization of an electron gun for ultrafast electron microscopy." Doctoral thesis, 2015. http://hdl.handle.net/11858/00-1735-0000-0028-867D-4.
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Priebe, Katharina Elisabeth. "Coherent Control and Reconstruction of Free-Electron Quantum States in Ultrafast Electron Microscopy." Thesis, 2017. http://hdl.handle.net/11858/00-1735-0000-002E-E30D-2.
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"Ultrafast Femtosecond Laser Beam Shaping and Its Applications in Two-Photon Excitation Microscopy." 2016. http://repository.lib.cuhk.edu.hk/en/item/cuhk-1292485.
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Kuo, Yung-En, and 郭永恩. "Applications of Ultrafast Lasers on Super Resolution Microscopy and Investigation of Myocyte Cells." Thesis, 2010. http://ndltd.ncl.edu.tw/handle/72744340339819030368.
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碩士國立陽明大學
生醫光電工程研究所
98
Ultrafast pulsed laser (pulse width from tens femtosecond i.e. 10−15 second to picoseconds i.e. 10−12 second) is a mature laser technology which developed very well in recent years, it’s multiple applications are not only in industry but also academia. In academy, the applications include ultrafast phenomena, multi-photon microscopy, photochemistry and so on. In industry, it was applied in producing and processing on high precision components. This research utilizes the characteristic of ultrafast pulse lasers and investigates the application of far-field optical super-resolution microscopy and the research of mycyte cells stimulation. First we utilize the ultrafast pulse laser as our far-field super-resolution light source. Super-resolution microscopy is the foreground of the microscopy in recent 10~20 years. Because of the conventional optical microscopy are limited by diffraction limit, it can not resolve organelle structure and molecule interaction inside the cell , these properties usually occur under tens to a few nanometer scale, however the diffraction limit is about 200 nm. The far-field optical super-resolution we studied is called STED (Stimulated Emission Depletion) which was first innovated by Dr. Stefan W. Hell in 1994, who is now doing research in Max Plank Institute. The principle is using the “stimulated emission”, as we utilize another beam to make the outer area of fluorescence molecules to be stimulated emission, then the effective emitting area become smaller, so as to break the spatial diffraction limit, it can reach tens of nanometer spatial resolution. Secondly, we utilize ultrafast laser to generate stress wave to affect several living cells, and study the effect after the mechanical stress. When an amplify femtosecond pulsed laser is focused in fluid, high intensity energy induce ablation phenomenon and create transient shockwave and bubbles simultaneously. This micron range stress wave push and shake the cells. We estimate the cell growth rate by counting the cells numbers to see if the cells stimulated by the mechanical stress or not.
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(6318551), Jordan M. Snaider. "CARRIER TRANSPORT IN HYBRID LEAD HALIDE PEROVSKITES STUDIED BY ULTRAFAST PUMP-PROBE MICROSCOPY." Thesis, 2019.
Find full textAbstract:
Insight into the nanoscale carrier transport in the rapidly developing class of solutionprocessed semiconductors known as metal halide perovskites is the focal point for these studies.
Further advancement in fundamentally understanding photophysical processes associated with
charge carrier transport is needed to realize the true potential of perovskites for photovoltaic
applications. In this work, we study photogenerated carrier transport to understand the underlying
transport behavior of the material on the 10s to 100s nanometer lengthscales. To study these
processes, we employ a temporally-resolved and spatially-resolved technique, known as transient
absorption microscopy, to elucidate the charge carrier dynamics and propagation associated with
metal halide perovskites. This technique provides a simultaneous high temporal resolution (200
fs) and spatial resolution (50 nm) to allow for direct visualization of charge carrier migration on
the nanometer length scale. There are many obstacles these carriers encounter between
photogeneration and charge collection such as morphological effects (grain boundaries) and carrier
interactions (scattering processes). We investigate carrier transport on the nanoscale to understand
how morphological effects influence the materials transport behavior. Morphological defects such
as voids and grain boundaries are inherently small and traditionally difficult to study directly.
Further, because carrier cooling takes place on an ultrafast time scale (fs to ps), the combined
spatial and temporal resolution is necessary for direct probing of hot (non-equilibrium) carrier
transport. Here we investigate a variety of ways to enhance carrier transport lengthscales by studying how non-equilibrium carriers propagate throughout the material, as well as, carrier
cooling mechanisms to extend the non-equilibrium regime.
For optoelectronic devices based on polycrystalline semiconducting thin films, grain
boundaries are important to consider since solution-based processing results in the formation of
well-defined grains. In Chapter 3, we investigate equilibrium carrier transport in metal halide
perovskite thin films that are created via the highly desired solution processing method. Carrier
transport across grain boundaries is an important process in defining efficiency due to the literary
discrepancies on whether the grains limit carrier transport or not. In this work, we employ transient
absorption microscopy to directly measure carrier transport within and across the boundaries. By
selectively imaging sub-bandgap states, our results show that lateral carrier transport is slowed
down by these states at the grain boundaries. However, the long carrier lifetimes allow for efficient
transport across the grain boundaries. The carrier diffusion constant is reduced by about a factor
of 2 for micron-sized grain samples by the grain boundaries. For grain sizes on the order of ∼200
nm, carrier transport over multiple grains has been observed within a time window of 5 ns. These
observations explain both the shortened photoluminescence lifetimes at the boundaries as well as
the seemingly benign nature of the grain boundaries in carrier generation. The results of this work
provide insight into why this defect tolerant material performs so well.
Photovoltaic performance (power conversion efficiency) is governed by the ShockleyQueisser limit which can be overcame if hot carriers can be harvested before they thermalize. To
convert sunlight to usable electricity, the photogenerated charge carriers need to migrate long
distances and or live long enough to be collected. It is unclear whether these hot carriers can
migrate a long enough distance for efficient collection. In Chapter 4, we report direct visualization
of hot-carrier migration in methylammonium lead iodide (CH3NH3PbI3) thin films by ultrafast transient absorption microscopy. This work demonstrates three distinct transport regimes. (i)
Quasiballistic transport, (ii) nonequilibrium transport, and (iii) diffusive transport. Quasiballistic
transport was observed to correlate with excess kinetic energy, resulting in up to 230 nanometers
of transport distance that could overcome grain boundaries. The nonequilibrium transport
persisted over tens of picoseconds and ~600 nanometers before reaching the diffusive transport
limit. These results suggest potential applications of hot-carrier devices based on hybrid
perovskites to ultimately overcome the Shockley-Queisser limit.
In the next work, we investigated a way to extend non-equilibrium carrier lifetime, which
ultimately corresponds to an accelerated carrier transport. From the knowledge of the hot carrier
transport work, we showed a proof of concept that the excess kinetic energy corresponds to long
range carrier transport. To further develop the idea of harvesting hot carriers, one must investigate
a way to make the carriers stay hot for a longer period (i.e. cool down slower). In Chapter 5, we
slow down the cooling of hot carriers via a phonon bottleneck, which points toward the potential
to overcome the Shockley-Queisser limit. Open questions remain on whether the high optical
phonon density from the bottleneck impedes the transport of these hot carriers. We show a direct
visualization of hot carrier transport in the phonon bottleneck regime in both single crystalline and
polycrystalline lead halide perovskites, more specifically, a relatively new class of alkali metal
doped perovskites (RbCsMAFA), which has one of the highest power conversion efficiencies.
Remarkably, hot carrier diffusion is enhanced by the presence of a phonon bottleneck, the exact
opposite from what is observed in conventional semiconductors such as GaAs. These results
showcase the unique aspects of hot carrier transport in hybrid perovskites and suggest even larger
potential for hot carrier devices than previously envisioned by the initial results presented in
Chapter 4. The final chapter will be divided into two sections, as we summarize and highlight our
collaborative efforts towards homogenization of carrier dynamics via doping perovskites with
alkali metals and our work on two-dimensional hybrid quantum well perovskites. Further studies
on the champion solar cell (RbCsMAFA) were performed to elucidate the role inorganic cations
play in this material. By employing transient absorption microscopy, we show that alkali metals
Rb+
and Cs+
are responsible for inducing a more homogenous halide (Iand Br-
) distribution,
despite the partial incorporation into the perovskite lattice. This translates into improved electronic
dynamics, including fluorescence lifetimes above 3 µs and homogenous carrier dynamics, which
was visualized by ultrafast microscopy. Additionally, there is an improvement in photovoltaic
device performance. We find that while Cs cations tend to distribute homogenously across the
perovskite grain, Rb and K cations tend to phase segregate at precursor concentrations as low as
1%. These precipitates have a counter-productive effect on the solar cell, acting as recombination
centers in the device, as argued from electron beam-induced current measurements. Remarkably,
the high concentration of Rb and Cs agglomerations do not affect the open-circuit voltage, average
lifetimes, and photoluminescence distribution, further indicating the perovskite’s notorious defect
tolerance.
A new class of high-quality two dimensional organic-inorganic hybrid perovskite quantum
wells with tunable structures and band alignments was studied. By tuning the functionality of the
material, the strong self-aggregation of the conjugated organic molecules can be suppressed, and
2D organic-halide perovskite superlattice crystals and thin films can be easily obtained via onestep solution-processing. We observe energy transfer and charge transfer between adjacent
organic and inorganic layers, which is extremely fast and efficient (as revealed by ultrafast
spectroscopy characterizations). Remarkably, these 2D hybrid perovskite superlattices are stable, due to the protection of the bulky hydrophobic organic groups. This is a huge step towards the
practicality of using perovskites for optoelectronics, since stability is always a huge concern with
water-sensitive materials. The molecularly engineered 2D semiconductors are on par with III-V
quantum wells and are promising for next-generation electronics, optoelectronics, and photonics.
39
Gunther, Aimee Kirsten. "Ultrafast coincidence characteristics of entangled photons towards entangled two-photon absorption." Thesis, 2014. http://hdl.handle.net/10012/8234.
Full textAbstract:
Nonlinear optics has had extensive application into a vast array of scientific fields. One such nonlinear process, two-photon absorption (TPA), has had a wildly successful
adoption into the field of biological imaging and microscopy. As far and as fast as this field is progressing, limitations stemming from the use of ultrafast lasers are starting to appear.
In this work, an alternative nonclassical light source will be motivated for the application
of low photon-flux two-photon microscopy. The origin and properties of the chosen
nonclassical source, spontaneous parametric downconversion (SPDC), will be discussed along with the spatial and spectral properties modelled. Nonlinear processes such as TPA and sum frequency generation (SFG) will be viewed as "ultrafast coincidence measurements" of two photons arriving at a molecule within the time window of excitation. These ultrafast coincidence measurements will be viewed in an alternative manner: in terms of the second-order coherence from a light source. This degree of second-order coherence can be subdivided into two categories arising from different combinations of correlations within and between entangled photon pairs. Of interest, the energy-time correlations within the photon pair allow for enhancements in ultrafast coincidence rates over coherent light sources. The makings of an experimental setup to demonstrate enhanced rates from ultrafast two-photon coincidences taking place in SFG in a nonlinear crystal will be discussed.
40
Yang, Te-chen, and 楊德振. "The Applications of Ultrafast laser in Laser Scanning Microscopy：RFOBIC and Two Photon UV Fluorescence Microscopy." Thesis, 2004. http://ndltd.ncl.edu.tw/handle/27236912626240143267.
Full textAbstract:
碩士國立中山大學
物理學系研究所
92
In this study, the characteristic properties of the ultrafast laser exhibit sufficiently in the application of RFOBIC and two-photon UV fluorescence. This laser can be used to measure photonic components with fast responding speed due to the ultrashort pulse and broad bandwidth which is RF bandwidths of greater than 1.8THz. we have demonstrated the use of a frequency-doubled femtosecond optical parametric oscillator in generating two-photon excitation that is equivalent to ultraviolet(UV) light with wavelength less than 300 nm. This capability allows observation of some amino acids and enables excitation that is only possible with wavelength in UVB range(290 nm-320 nm)
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Shaheen, Basamat S. "Real-Space Imaging of Charge Carrier Dynamics in Photoactive Materials by 40 Scanning Ultrafast Electron Microscopy." Diss., 2019. http://hdl.handle.net/10754/653701.
Full textAbstract:
Surfaces of photoactive materials play a pivotal role in determining the interfacial properties and the photoconversion efficiency of optoelectronic devices. On the other hand, the fundamental photophysical processes of photo-generated carriers and their transport and recombination occur at extremely short timescales ranging from femtoseconds to nanoseconds. In order to provide a complete picture about the best working conditions of photoactive materials to improve their device performance, it is very essential to explore and decipher the ultrafast surface dynamics at nanoscale or even atomic levels. Four-dimensional scanning ultrafast electron microscopy (4D S-UEM) is the sole technique capable of surface-selective visualization of light-triggered carrier dynamics at nanometer scale. Herein, 4D S-UEM is used to investigate the effect of several key factors on the surface charge carrier dynamics of a variety of photoactive materials: (1) surface passivation in lnGaN nanowires, (2) deposition method in PbS quantum dots,(3) thickness in CdSe thin films, (4) crystal orientation in CdTe single crystals and (5) native oxide layer in Si wafers. Besides the visualization of surface charge carrier dynamics in these materials, new surface features were discovered such as the superior charge carrier diffusion on the surfaces of CdTe single crystals ≈ 10^4 times larger than that in their crystal's bulk. Furthermore, utilizing 4D S-UEM at low accelerating voltage of 1 kV enables monitoring the diffusion from underneath the surface region and discovering the reason behind the energy loss mechanism and ultrafast carrier recombination of surface charge carriers in solar cell materials, unlocking their interfacial behaviors at the nanoscale level. These new findings are believed to provide the foundation for potential applications of 4D S-UEM to be the method of choice in studies of surface dynamics in chemistry, materials science, and other disciplines. Furthermore, the work presented here provides the key to unlocking further optimizations of the surfaces and interfaces of photoactive materials, thus paving the way for more efficient optoelectronic devices.
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Tseng, Ming-Lun, and 曾銘綸. "Nano fabrication and measurement of phase-change thin film by ultrafast laser and atomic force microscopy." Thesis, 2010. http://ndltd.ncl.edu.tw/handle/82685684794523274472.
Full textAbstract:
碩士臺灣大學
物理研究所
98
Phase change materials has different optical and electrical properties in crystalline and amorphous state, it has been applied to versatile areas such as optical data storage, phase change memory, nanolithography. In this paper, we present a laser-induced forward transfer technique to fabricate the pattern with phase change material Ge2Sb2Te5. The as-deposited Ge2Sb2Te5 alloy films on a transparent substrate are transferred to the receiver substrate after a femto-second laser pulse irradiation (wavelength is 800 nm, and pulse duration is 140 femto-second). The dots patterns are fabricated with different volume and height-width ratio by changing the laser fluence and the thickness of the donor film. The topography of receiver substrate is studied by atomic force microscopy (AFM) and the optical measure system, the transfer properties are analyzed. According to the AFM measured information, we found that the dot diameter is function of Ge2Sb2Te5 donor film thickness and laser fluence. The dot size is around 14 nm (thickness) x 1500 nm (diameter). Fabrication of patterns composed of dots deposited on the receiver substrate was measured. This technique provides a simple way to form arbitrary pattern and has potential in future production of optical components, MEMS and phase-change memory.
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(6577541), Long Yuan. "Spatial and Temporal Imaging of Exciton Dynamics and transport in two-dimensional Semiconductors and heterostructures by ultrafast transient absorption microscopy." Thesis, 2019.
Find full textAbstract:
Recently, atomically thin two-dimensional (2D) layered materials such as graphene and transition metal dichalcogenides (TMDCs) have emerged as a new class of materials due to their unique electronic structures and optical properties at the nanoscale limit. 2D materials also hold great promises as building blocks for creating new heterostructures for optoelectronic applications such as atomically thin photovoltaics, light emitting diodes, and photodetectors. Understanding the fundamental photo-physics process in 2D semiconductors and heterostructures is critical for above-mentioned applications.
In Chapter 1, we briefly describe photo-generated charge carriers in two-dimensional (2D) transition metal dichalcogenides (TMDCs) semiconductors and heterostructures. Due to the reduced dielectric screening in the single-layer or few-layer of TMDCs semiconductors, Columbo interaction between electron and hole in the exciton is greatly enhanced that leads to extraordinary large exciton binding energy compared with bulk semiconductors. The environmental robust 2D excitons provide an ideal platform to study exciton properties in TMDCs semiconductors. Since layers in 2D materials are holding by weak van de Waals interaction, different 2D layers could be assembled together to make 2D heterostructures. The successful preparation of 2D heterostructures paves a new path to explore intriguing optoelectronic properties.
In Chapter 2, we introduce various optical microscopy techniques used in our work for the optical characterization of 2D semiconductors and heterostructures. These optical imaging tools with high spatial and temporal resolution allow us to directly track charge and energy flow at 2D interfaces.
Exciton recombination is a critical factor in determining the efficiency for optoelectronic applications such as semiconductor lasers and light-emitting diodes. Although exciton dynamics have been investigated in different 2D semiconductor, large variations in sample qualities due to different preparation methods have prevented obtaining intrinsic exciton lifetimes from being conclusively established. In Chapter 3, we study exciton dynamics in 2D TMDCs semiconductors using ultrafast PL and transient absorption microscopy. Here we employ 2D WS2 semiconductor as a model system to study exciton dynamics due to the low defect density and high quantum yield of WS2. We mainly focus on how the exciton population affects exciton dynamics. At low exciton density regime, we demonstrate how the interlayer between the bright and dark exciton populations influence exciton recombination. At high exciton density regime, we exhibit significant exciton-exciton annihilation in monolayer WS2. When comparing with the bilayer and trilayer WS2, the exciton-exciton annihilation rate in monolayer WS2 increases by two orders of magnitude due to enhanced many-body interactions at single layer limit.
Long-range transport of 2D excitons is desirable for optoelectronic applications based on TMDCs semiconductors. However, there still lacks a comprehensive understanding of the intrinsic limit for exciton transport in the TMDCs materials currently. In Chapter 4, we employ ultrafast transient absorption microscopy that is capable of imaging excitons transport with ~ 200 fs temporal resolution and ~ 50 nm spatial precision to track exciton motion in 2D WS2 with different thickness. Our results demonstrate that exciton mobility in single layer WS2 is largely limited by extrinsic factors such as charge impurities and surface phonons of the substrate. The intrinsic phonon-limited exciton transport is achieved in WS2 layers with a thickness greater than 20 layers.
Efficient photocarrier generation and separation at 2D interfaces remain a central challenge for many optoelectronic applications based on 2D heterostructures. The structural tunability of 2D nanostructures along with atomically thin and sharp 2D interfaces provides new opportunities for controlling charge transfer (CT) interactions at 2D interfaces. A largely unexplored question is how interlayer CT interactions contribute to interfacial photo-carrier generation and separation in 2D heterostructures. In Chapter 5, we present a joint experimental and theoretical study to address carrier generation from interlayer CT transitions in WS2-graphene heterostructures. We use spatially resolved ultrafast transient absorption microscopy to elucidate the role of interlayer coupling on charge transfer and photo-carrier generation in WS2-graphene heterostructures. These results demonstrate efficient broadband photo-carrier generation in WS2-graphene heterostructures which is highly desirable for atomically thin photovoltaic and photodetector applications based on graphene and 2D semiconductors.
CT exciton transport at heterointerfaces plays a critical role in light to electricity conversion using 2D heterostructures. One of the challenges is that direct measurements of CT exciton transport require quantitative information in both spatial and temporal domains. In order to address this challenge, we employ transient absorption microscopy (TAM) with high temporal and spatial resolution to image both bright and dark CT excitons in WS2-tetrance and CVD WS2-WSe2 heterostructure. In Chapter 6, we study the formation and transport of interlayer CT excitons in 2D WS2-Tetracene vdW heterostructures. TAM measurements of CT exciton transport at these 2D interfaces reveal coexistence of delocalized and localized CT excitons. The highly mobile delocalized CT excitons could be the key factor to overcome large CT exciton binding energy in achieving efficient charge separation. In Chapter 7, we study stacking orientational dependent interlayer exciton recombination and transport in CVD WS2-WSe2 heterostructures. Temperature-dependent interlayer exciton dynamics measurements suggest the existence of moiré potential that localizes interlayer excitons. TAM measurements of interlayer excitons transport reveal that CT excitons at WS2-WSe2 heterointerface are much more mobile than intralayer excitons of WS2. We attributed this to the dipole-dipole repulsion from bipolar interlayer excitons that efficiently screen the moiré potential fluctuations and facilitate interlayer exciton transport. Our results provide fundamental insights in understanding the influence of moiré potential on interlayer exciton dynamics and transport in CVD WS2-WSe2 heterostructures which has important implications in optoelectronic applications such as atomically thin photovoltaics and light harvesting devices.
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Jagannadh, Veerendra Kalyan. "Point-of-Care High-throughput Optofluidic Microscope for Quantitative Imaging Cytometry." Thesis, 2017. http://hdl.handle.net/2005/3274.
Full textAbstract:
Biological research and Clinical Diagnostics heavily rely on Optical Microscopy for analyzing properties of cells. The experimental protocol for con-ducting a microscopy based diagnostic test consists of several manual steps, like sample extraction, slide preparation and inspection. Recent advances in optical microscopy have predominantly focused on resolution enhancement. Whereas, the aspect of automating the manual steps and enhancing imaging throughput were relatively less explored. Cost-e ective automation of clinical microscopy would potentially enable the creation of diagnostic devices with a wide range of medical and biological applications. Further, automation plays an important role in enabling diagnostic testing in resource-limited settings.
This thesis presents a novel optofluidics based approach for automation of clinical diagnostic microscopy. A system-level integrated optofluidic architecture, which enables the automation of overall diagnostic work- ow has been proposed. Based on the proposed architecture, three different prototypes, which can enable point-of-care (POC) imaging cytometry have been developed. The characterization of these prototypes has been performed. Following which, the applicability of the platform for usage in diagnostic testing has been validated. The prototypes were used to demonstrate applications like Cell Viability Assay, Red Blood Cell Counting, Diagnosis of Malaria and Spherocytosis.
An important performance metric of the device is the throughput (number of cells imaged per second). A novel microfluidic channel design, capable of enabling imaging throughputs of about 2000 cells per second has been incorporated into the instrument. Further, material properties of the sample handling component (microfluidic device) determine several functional aspects of the instrument. Ultrafast-laser inscription (ULI) based glass microfluidic devices have been identi ed and tested as viable alternatives to Polydimethylsiloxane (PDMS) based microfluidic chips. Cellular imaging with POC platforms has thus far been limited to acquisition of 2D morphology. To potentially enable 3D cellular imaging with POC platforms, a novel slanted channel microfluidic chip design has been proposed. The proposed design has been experimentally validated by performing 3D imaging of fluorescent microspheres and cells. It is envisaged that the proposed innovation would aid to the current e orts towards implementing good quality health-care in rural scenarios. The thesis is organized in the following manner :
The overall thesis can be divided into two parts. The first part (chapters 2, 3) of the thesis deals with the optical aspects of the proposed Optofluidic instrument (development, characterization and validations demonstrating its use in poc diagnostic applications). The second part (chapters 4,5,6) of the thesis details the microfluidic sample handling aspects implemented with the help of custom fabricated microfludic devices, the integration of the prototype, func-tional framework of the device.
Chapter 2 introduces the proposed optofluidic architecture for implementing the POC tool. Further, it details the first implementation of the proposed platform, based on the philosophy of adapting ubiquitously available electronic imaging devices to perform cellular diagnostic testing. The characterization of the developed prototypes is also detailed.
Chapter 3 details the development of a stand-alone prototype based on the proposed architecture using inexpensive o -the-shelf, low frame-rate image sensors. The characterization of the developed prototype and its performance evaluation for application in malaria diagnostic testing are also presented. The chapter concludes with a comparative evaluation of the developed prototypes, so far.
Chapter 4 presents a novel microfludic channel design, which enables the enhancement of imaging throughput, even while employing an inexpensive low frame-rate imaging modules. The design takes advantage of radial arrangement of microfludic channels for enhancing the achievable imaging throughput. The fabrication of the device and characterization of achievable throughputs is presented. The stand-alone optofluidic imaging system was then integrated into a single functional unit, with the proposed microfluidic channel design, a viscoelastic effect based micro uidic mixer and a suction-based microfluidic pumping mechanism.
Chapter 5 brings into picture the aspect of the material used to fabricate the sample handling unit, the robustness of which determines certain functional aspects of the device. An investigative study on the applicability of glass microfluidic devices, fabricated using ultra-fast laser inscription in the context of the microfluidics based imaging flow cytometry is presented. As detailed in the introduction, imaging in poc platforms, has thus far been limited to acquisition of 2D images. The design and implementation of a novel slanted channel microfluidic chip, which can potentially enable 3D imaging with simplistic optical imaging systems (such as the one reported in the earlier chapters of this thesis) is detailed. A example application of the proposed microfludic chip architecture for imaging 3D fluorescence imaging of cells in flow is presented.
Chapter 6 introduces a diagnostic assessment framework for the use of the developed of m in an actual clinical diagnostic scenario. The chapter presents the use of computational signatures (extracted from cell images) to be employed for cell recognition, as part of the proposed framework. The experimental results obtained while employing the framework to identify cells from three different leukemia cell lines have been presented in this chapter.
Chapter 7 summarizes the contributions reported in this thesis. Potential future scope of the work is also detailed.
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Schröder, Benjamin. "Probing Light-Matter Interactions in Plasmonic Nanotips." Doctoral thesis, 2020. http://hdl.handle.net/21.11130/00-1735-0000-0005-1473-3.
Full text
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Yalcin, Sibel Ebru. "Characterization and interactions of ultrafast surface plasmon pulses." 2010. https://scholarworks.umass.edu/dissertations/AAI3427612.
Full textAbstract:
Surface Plasmon Polaritons (SPPs) are considered to be attractive components for plasmonics and nanophotonic devices due to their sensitivity to interface changes, and their ability to guide and confine light beyond the diffraction limit. They have been utilized in SPP resonance sensors and near field imaging techniques and, more recently, SPP experiments to monitor and control ultrafast charge carrier and energy relaxation dynamics in thin films. In this thesis, we discuss excitation and propagation properties of ultrafast SPPs on thin extended metal films and SPP waveguide structures. In addition, localized and propagating surface plasmon interactions in functional plasmonic nanostructures will also be addressed. For the excitation studies of ultrafast SPPs, we have done detailed analysis of femtosecond surface plasmon pulse generation under resonant excitation condition using prism coupling technique. Our results show that photon-SPP coupling is a resonant process with a finite spectral bandwidth that causes spectral phase shift and narrowing of the SPP pulse spectrum. Both effects result in temporal pulse broadening and, therefore, set a lower limit on the duration of ultrafast SPP pulses. These findings are necessary for the successful integration of plasmonic components into high-speed SPP circuits and time-resolved SPP sensors. To demonstrate interactions between localized and propagating surface plasmons, we used block-copolymer based self assembly techniques to deposit long range ordered gold nanoparticle arrays onto silver thin films to fabricate composite nanoparticle thin film structures. We demonstrate that these gold nanoparticle arrays interact with SPPs that propagate at the film/nanoparticle interface and therefore, modify the dispersion relation of SPPs and lead to strong field localizations. These results are important and advantageous for plasmonic device applications. For the propagation studies of ultrafast SPPs, we have designed and constructed a home-built femtosecond photon scanning tunneling microscope (fsPSTM) to visualize ultrafast SPPs in photonic devices based on metal nanostructures. Temporal and phase information have been obtained by incorporating the fsPSTM into one arm of a Mach-Zehnder interferometer, allowing heterodyne detection. Understanding plasmon propagation in metal nanostructures is a requirement for implementing such structures into optoelectronic and telecommunication technologies.