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Aardahl, Christopher L. "Electrodynamic trapping, manipulation, and Raman characterization of single particles and fine particulate clouds /." Thesis, Connect to this title online; UW restricted, 1997. http://hdl.handle.net/1773/9863.
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Kadiri, Youssef. "Soil Penetrometer with Ramon Sampling, Fluorescence and Reflected Light Imaging: A Feasibility Study." Thesis, Montana State University, 2005. http://etd.lib.montana.edu/etd/2005/kadiri/KadiriY0505.pdf.
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This thesis describes the feasibility and capabilities of a Fluorescence Imaging and Raman Probe (FIRP). This miniature instrument will combine reflected light and fluorescence imaging and Raman spectroscopy for potential exobiology or terrestrial environmental use. With the help of a penetrometer, the probe might be used to assess the presence of life on Mars and gain an understanding of Martian soil. Furthermore, this thesis will delineate how this penetrometer may be used to detect underground constituents and pollutants present on our own planet. The proposed FIRP will be incorporated into a penetrometer that will go several meters below the surface seeking bio-signatures and information about soil composition. Microscopic imaging with reflected light will provide morphological context, fluorescence imaging can provide biomass detection, and Raman spectrometry can provide chemical identification of imaged material. The fluorescence technique will mainly depend on the performance of a non-cooled low-noise monochrome imaging camera, optical filters, and high efficiency light emitting diodes in the UV and visible. This miniature instrument will be connected by optical fiber to a surface platform that will host the Raman spectrometer and Raman laser excitation source. This thesis will show the experimental results of a bench-top proof of concept system. Images and spectra were collected and analyzed. Important choices and characteristics of the optical design are discussed relative to Raman and fluorescence detection. Finally, the thesis will propose a prototype of a compact device that combines both sensing methods and is compatible with a penetrometer platform.
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Muguro, Kennedy Mwaura. "Effects of polarization in a distributed raman fibre amplifier." Thesis, Nelson Mandela Metropolitan University, 2011. http://hdl.handle.net/10948/d1014621.
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The need to exploit the large fibre bandwidth and increase the reach has seen the application of the Raman fibre amplifier (RFA) become indispensable in modern light wave systems. The success and resilience of RFAs in optical communication is deeply rooted in their unique optical properties and new technologies which have allowed the amplifier to come of age. However, the full potential of RFAs in optical communication and other applications are yet to be realized. More so are its polarization properties which still remain largely unexploited and have not been fully understood. In this work, fundamental issues regarding distributed RFA have been investigated with the aim of acquiring a better understanding of the amplifier polarization characteristics which have potential applications. In particular the effects of polarization mode dispersion (PMD) and polarization dependent loss (PDL) have been demonstrated both by simulation and experiment. The possibility of Raman polarization pulling in single mode fibres (SMFs) has also been addressed. Polarization sensitivity of RFA has been known for a long time but the clear manifestation of it has become evident in the advent of modern low PMD fibre. Unlike EDFAs which make use of special doped fibre, RFAs require no special fibre for operation. Besides, RFA uses a very long length of fibre and as such the fibre polarization characteristics come into play during amplification. In the demonstrations presented in this thesis a fibre of PMD coefficient < 0.05 pskm-1/2 was regarded as low PMD fibre while one having coefficient ≥ 0.05 pskm-1/2 was categorized to have high PMD unless otherwise stated. Several experiments were performed to evaluate the RFA gain characteristics with respect to fibre PMD and the system performance in the presence of noise emanating from amplified spontaneous emission (ASE). Analysis of Raman gain statistics was done for fibres of low and high PMD coefficients. The statistics of PDG and on-off gain were eventually used to demonstrate the extraction of PMD coefficients of fibres between 0.01- 0.1 pskm-1/2 using a forward pumping configuration. It was found that, at increasing pump power a linear relationship exists between forward and backward signal gain on a dB scale. The interaction of PDL and Raman PDG in the presence of PMD were observed at very fundamental level. It was found the presence of PDL serves to reduce the available on-off gain. It was also established that the presence of PMD mediates the interaction between PDG/PDL. When PMD is high it reduces PDG but the presence of PDL introduces a wavelength dependent gain tilting for WDM channels. Further analysis revealed that signal polarization is influenced by the pump SOP due to the pulling effect which is present even at moderate pump power.
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Nicolas, Rana. "Squeezing light in nanoparticle-film plasmonic metasurface : from nanometric to atomically thin spacer." Thesis, Troyes, 2015. http://www.theses.fr/2015TROY0028/document.
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Les plasmons polaritons de surface (SPP) et les plasmons localisés de surface (LSP) font l’objet de nombreuses investigations du fait de leur fort potentiel technologique. Récemment, une attention particulière a été portée à des systèmes supportant ces deux types de résonances en déposant des nanoparticules (NPs) métalliques sur des films minces métalliques. Plusieurs études ont mis en évidence le couplage et l’hybridation entre modes localisés et délocalisés. Cependant, une compréhension en profondeur des propriétés optiques et du potentiel de ces interfaces est toujours manquante. Nous avons mené ici une étude de systèmes NPs/film couplés. Nous avons étudié à la fois expérimentalement et théoriquement l’influence d’une couche séparatrice ultra-mince en SiO2 ainsi que l’évolution des différents modes plasmoniques pour différentes épaisseurs. Nous avons ainsi mis en lumière que de tels systèmes couplés offrent des propriétés optiques exaltées et une large accordabilité spectrale. Nous avons aussi cherché à diminuer l’épaisseur de la couche séparatrice vers le cas ultime monoatomique en utilisant le graphène. Du fait du caractère non-diélectrique de celui-ci, nous avons mis en évidence un comportement optique inattendu de la résonance plasmonique. Nous avons expliqué celui-ci par la mise en évidence du dopage du graphène par les NPs, ce qui est un premier pas en direction de dispositifs optoélectroniques à base de graphène. Enfin, après avoir amélioré notre compréhension théorique de ces systèmes, nous avons évalué leur potentiel comme capteurs SERS ou LSP<br>Surface plasmon polariton (SPP) and Localized surface plasmon (LSP) have attracted numerous researchers due to their high technological potential. Recently, strong attention was paid to the potential of SPP and LSP combinations by investigating metallic nanoparticles (NPs) on top of metallic thin films. Several studies on such systems have shown the coupling and hybridization between localized and delocalized modes. In this work, we propose a full systematic study on coupled NP/film systems with Au NPs and Au films. We investigate both experimentally and theoretically the influence of an ultra-thin SiO2 dielectric spacer layer, as well as the evolution of the plasmonic modes as the spacer thickness increases. We show that coupled systems exhibit enhanced optical properties and larger tunability compared to uncoupled systems. We also compare these results with those measured for coupled interfaces using graphene as a non-dielectric sub-nanometer spacer. Introducing graphene adds complexity to the system. We show that such coupled systems also exhibit enhanced optical properties and larger tunability of their spectral properties compared to uncoupled systems as well as unexpected optical behavior. We explain this behavior by evidencing graphene doping by metallic NPs, which can be a first step towards graphene based optoelectronic devices. After establishing a deep understanding of coupled systems we perform both SERS and RI sensing measurements to validate the high potential of these plasmonic interfaces
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Souther, Nathan Jon. "Light Shift Measurements of Cold Rubidium Atoms using Raman Pump-Probe Spectroscopy." Miami University / OhioLINK, 2009. http://rave.ohiolink.edu/etdc/view?acc_num=miami1250622906.
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Bassi, Andrea Li. "X-ray and light scattering from nanostructured thin films." Thesis, Durham University, 2000. http://etheses.dur.ac.uk/4631/.
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The object of this thesis is the study of nanostructured thin films using inelastic fight scattering and elastic x-ray scattering techniques. Their use in combination with other techniques is a powerful tool for the investigation of nanostructured materials. X-ray, Raman and Brillouin characterisation of cluster-assembled carbon films, promising for applications in the field of catalysis, hydrogen storage and field emission, is here presented. X-ray reflectivity (XRR) provided a measure of the density. Raman spectroscopy showed that the local bonding in these amorphous films depends on the size distribution of the clusters and that it is possible to select the cluster size in order to grow films with tailored properties. Brillouin scattering provided a characterisation at the mesoscopic scale and an estimate of the elastic constants, revealing a very soft material. XRR was employed to study density, layering and roughness of a wide range of amorphous carbon films grown with different techniques. Some films possess an internal layering due to plasma instabilities in the deposition apparatus. By comparing XRR with Electron Energy Loss Spectroscopy, a unique value for the electron "effective mass" was deduced and a general relationship between sp(^3)-content and density was found. XRR and H effusion were used to determine the hydrogen content. A study of the size-dependent melting temperature in tin nanoparticle thin films was undertaken with a combined use of X-Ray Diffraction (XRD) and light scattering. A redshift in the position of a Rayleigh peak in the temperature-dependent Brillouin measurements was shown to be related to the melting of the nanoparticles and explained by an effective medium model. XRD also provided information on the low-level of stress in the particles. Low-frequency Raman scattering was used to study the behaviour of the acoustic modes of a single particle as a function of temperature.
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Chikkaraddy, Rohit. "Light and single-molecule coupling in plasmonic nanogaps." Thesis, University of Cambridge, 2018. https://www.repository.cam.ac.uk/handle/1810/274552.
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Plasmonic cavities confine optical fields at metal-dielectric interfaces via collective charge oscillations of free electrons within metals termed surface plasmon polaritons (SPPs). SPPs are confined in nanometre gaps formed between two metallic surfaces which creates an optical resonance. This optical resonance of the system is controlled by the geometry and the material of the nanogap. The focus of this work is to understand and utilize these confined optical modes to probe and manipulate the dynamics of single-molecules at room temperature. In this thesis, nanogap cavities are constructed by placing nanoparticles on top of a metal-film separated by molecular spacers. Such nanogaps act as cavities with confined optical fields in the gap. Precise position and orientation of single-molecules in the gap is obtained by supramolecular guest-host assembly and DNA origami breadboards. The interaction of light and single-molecules is studied in two different regimes of interaction strength. In the perturbative regime molecular light emission from electronic and vibrational states is strongly enhanced and therefore is used for the detection of single-molecules. In this regime the energy states remain unaltered, however profound effects emerge when the gap size is reduced to < 1 nm. New hybridized energy states which are half-light and half-matter are then formed. Dispersion of these energies is studied by tuning the cavity resonance across the molecular resonance, revealing the anti-crossing signature of a strongly coupled system. This dressing of molecules with light results in the modification of photochemistry and photophysics of single-molecules, opening up the exploration of complex natural processes such as photosynthesis and the possibility to manipulate chemical bonds.
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Bright, Andrew G. "Mechanistic Insights into the Stabilisation of Biopharmaceuticals using Glycine Derivatives. The Effect of Glycine Derivatives on the Crystallisation, Physical Properties and Behaviour of Commonly used Excipients to Stabilise Antigens, Adjuvants and Proteins in the Solid State." Thesis, University of Bradford, 2015. http://hdl.handle.net/10454/15943.
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This dissertation has focused on studying the effect of four glycine derivatives on the solid state properties of mannitol, glycine, and sucrose when freeze dried into blended mixtures. The primary goal was to assess their value for use in the stabilisation of vaccines in the solid state, by examining key physical and chemical characteristics, which have been documented to be beneficial to the stabilisation of biopharmaceutical formulations. The novel excipients; dimethyl glycine, and trimethyl glycine, were shown to retard the crystallisation and increase the overall glass transition temperature, of mannitol, when freeze dried as evidenced by DSC and Powder X-ray diffraction. Mannitol’s glass transition temperature increased from 100C to 12.650C and 13.610C when mixed with methyl-glycine and dimethyl glycine respectively. The glycine derivatives did not show the same effect on sucrose which remained amorphous regardless of the concentration of the other excipient. The different behaviour with the sucrose system was thought to be due to relatively high glass transition temperature of sucrose. Conversely glycine remained highly crystalline due it’s relatively low glass transition temperature. The novel excipient formulations were also assessed for their effect on the aggregation of the adjuvant aluminium hydroxide when freeze dried by Dynamic Light Scattering (DLS).The formulations containing the glycine derivatives all caused a decrease in the aggregation size of the adjuvant from ~26 μm, to 185 nm in the presence of methyl glycine. The effects of lysozyme and viral antigen on the adjuvants were also examined showing that the addition of the virus did not affect the size of the aggregates formed, however lysozyme showed significant decreases in the aggregates formed. Examination of the freezing method were also made showing that faster freezing rates produced smaller aggregates of the adjuvant. When investigating the rate at which the excipients lost water during secondary drying there was evidence of the formation of hydrates of glycine, trimethyl glycine, and mannitol has shown that the glycine derivatives have attributes which would be beneficial in stabilising vaccines in the solid state when freeze dried.
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Bradley, Larry D. "Pressure and temperature effects on bacteriorhodopsin light to dark adaptation studied by near-infrared raman spectroscopy." Honors in the Major Thesis, University of Central Florida, 1994. http://digital.library.ucf.edu/cdm/ref/collection/ETH/id/123.
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This item is only available in print in the UCF Libraries. If this is your Honors Thesis, you can help us make it available online for use by researchers around the world by following the instructions on the distribution consent form at http://library.ucf.edu/Systems/DigitalInitiatives/DigitalCollections/InternetDistributionConsentAgreementForm.pdf You may also contact the project coordinator, Kerri Bottorff, at kerri.bottorff@ucf.edu for more information.<br>Bachelors<br>Arts and Sciences<br>Physics
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Sjöqvist, Jonas. "Light interactions in flexible conjugated dyes." Doctoral thesis, Linköpings universitet, Beräkningsfysik, 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-109011.
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In this thesis methodological developments have been made for the description of flexible conjugated dyes in room temperature spectrum calculations. The methods in question target increased accuracy and efficiency by combining classical molecular dynamics (MD) simulations with time-dependent response theory spectrum calculations. For absorption and fluorescence spectroscopies a form of conformational averaging is used, where the final spectrum is obtained as an average of spectra calculated for geometries extracted from ground and excited state MD simulations. For infrared and Raman spectroscopies averaged spectra are calculated based on individual spectra, obtained for zero-temperature optimized molecular structures, weighted by conformational statistics from MD trajectories. Statistics for structural properties are also used in both cases to gain additional information about the systems, allowing more efficient utilization of computational resources. As it is essential that the molecular mechanics description of the system is highly accurate for methods of this nature to be effective, high quality force field parameters have been derived, describing the molecules of interest in either the MM3 or CHARMM force fields. These methods have been employed in the study of three systems. The first is a platinum(II) actylide chromophore used in optical power limiting materials, for which a ultraviolet/visible absorption spectrum has been calculated. The second is a family of molecular probes called luminescent conjugated oligothiophenes, used to detect and characterize amyloid proteins, for which both absorption and fluorescence spectra have been calculated. Finally, infrared and Raman spectra have been calculated for a group of branched oligothiophenes used in organic solar cells. In addition, solvation effects have been studied for conjugated poly\-eletrolytes in water, resulting in the development of two solvation models suitable for this class of molecules. The first uses a quantum meachanics/molecular mechanics (QM/MM) description, in which the solute mole\-cule is described using accurate quantum mechanical methods while the surrounding water molecules are described using point charges and polarizable point dipoles. The second discards the water entirely and removes the ionic groups of the solute. The QM/MM model provides highly accurate results while the cut-down model gives results of slightly lower quality but at a much reduced computational cost. Finally, a study of protein-dye interactions has been performed, with the goal of explaining changes in the luminescence properties of the LCO chromophores when in the presence of amyloid proteins. Results were less than conclusive.
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Mhaouech, Imed. "Étude du transport de charges dans le niobate de lithium massif et réalisation de fonctions électro-optiques dans le niobate de lithium périodiquement polarisé." Thesis, Université de Lorraine, 2017. http://www.theses.fr/2017LORR0032/document.
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Le premier volet de cette thèse est consacré à la modélisation des phénomènes de transport dans le LN. Partant d'une analyse critique des modèles de bande usuels, nous montrons leur inadéquation dans le cas du LN et nous proposons un modèle de saut basé sur la théorie des petits polarons. Nous étudions d'abord par simulation Monte-Carlo la décroissance d'une population de polarons liés NbLi4+ relaxant vers des pièges profonds FeLi3+. Nous montrons que les pièges FeLi3+ ont des rayons effectifs particulièrement grands, rayons qui augmentent encore à température décroissante, et limitent considérablement les longueurs de diffusion des polarons. Les résultats de simulations sont ensuite confrontés aux résultats expérimentaux obtenus par différentes techniques ; Absorption photo-induite, Raman, Enregistrement holographique et Pompe-sonde. Le deuxième volet de cette thèse est consacré aux applications électro-optiques dans le LN périodiquement polarisé (PPLN). Sous l’effet d’une tension électrique, l’indice de réfraction du PPLN est périodiquement diminué et augmenté, formant ainsi un réseau d’indice activable électriquement. Un premier composant utilisant l’effet électro-optique dans du PPLN a été développé et démontré expérimentalement. Dans ce composant, la lumière est défléchie sous l’effet de la tension électrique par le réseau d’indice. Ce déflecteur de Bragg atteint une efficacité de diffraction proche de 100% avec une faible tension de commande de l’ordre de 5 V. Un deuxième composant a également été proposé, où la lumière se propage perpendiculairement aux parois de domaines du PPLN. Dans cette configuration un réflecteur de Bragg électro-optique peut être réalisé<br>The first part of this thesis is devoted to the modeling of transport phenomena in the LN. From a critical analysis of the usual band models, we show their inadequacy in the case of LN and we propose a hopping model based on the theory of small polarons. We first study by Monte-Carlo simulation the population decay of bound polarons NbLi4+ in deep traps FeLi3+. We show that the traps (FeLi3+) have particularly large effective radii, which increase further at decreasing temperature, and considerably limit the diffusion lengths of the polarons. The results of simulations are then compared with experimental results obtained by different techniques; Light-induced absorption, Raman, Holographic storage and Pump-Probe. The second part of this thesis is devoted to electro-optical applications in the periodically poled LN (PPLN). Under the effect of an electrical voltage, the refractive index of the PPLN is periodically decreased and increased, thus forming an electrically activatable index grating. A first component using the electro-optical effect in PPLN has been developed and demonstrated experimentally. In this component, the light is deflected under the effect of the electrical voltage by the index grating. This Bragg deflector achieves a diffraction efficiency of close to 100% with a low drive voltage of the order of 5 V. A second component has also been proposed, where light propagates perpendicularly to the domain walls of the PPLN. In this configuration an electro-optic Bragg reflector can be realized
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Sirotkin, Sergey. "Low frequency modes from small nanoparticles (metal nanocrystals) to large nanospheres (viruses) : an inelastic light scattering study." Phd thesis, Université Claude Bernard - Lyon I, 2010. http://tel.archives-ouvertes.fr/tel-00847063.
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The doctoral thesis "Low frequency modes from small nanoparticles (metal nanocrystals) to large nanospheres (viruses): an inelastic light scattering study" is dedicated to investigations of the acoustic properties of different nano-objects : small metal nanoparticles and nanocrystals (D < 30 nm) and large colloid/viral particles (D _ 200 nm). Inelastic light Raman/Brillouin scattering is used as the main research tool to probe the nanoparticle vibrations and to determine their elastic and mechanical parameters. In the first chapter, the well developed theory of elasticity is used to perform a qualitative and nomenclatural analysis of solid sphere vibrations ; several theoretical models allowing to describe the nanoparticle vibrational behavior within a surrounding medium and how the eigenvibrations are modified due to inner crystalline elastic anisotropy are discussed. The second chapter is dedicated to the description of the physics of inelastic light scattering which derives from the fluctuations of the polarizability induced by vibrations. Two types of inelastic light scattering are described : Brillouin scattering which results from the coupling of incident light (photon) with acoustic propagative waves (phonon) in a bulk substance and Raman scattering which is a result of the interaction between an incident photon and localized vibrations, hence nanoparticle vibrations in the present study. As essential in our study, the detailed description and principles of operation of the spectroscopic tools (tandem Fabry-Perot) used to perform these very low frequency inelastic light scattering spectroscopies (between 3 and 300 GHz typically) are given. The third chapter focuses on the study of low frequency modes from small metallic nanoparticles. Three systems are investigated : AuAg and Cu nanoparticles embedded in a vitreous matrix and Au nanocrystals deposited on a surface. The AuAg system allowed to study a notably rich Raman spectrum featuring contributions from fundamental modes and high order harmonics. The experimental data were found to compare rather well with theoretical predictions, thereby providing more insight into the essential ingredients of Raman scattering from nanoparticle modes. The study of deposited Au nanocrystals allowed characterizing the effect of nanocrystalline quality which results in a partial lifting of degeneracy of the nanoparticle modes due to elastic anisotropy. Investigating the wavelength dependence of the Raman spectrum allows a differentiation between single nanocrystals and multiply twinned nanoparticles. Both embedment effects and nanocrystallinity effects are integrated in the study of Cu nanoparticles grown in a glass matrix, where the influence of annealing conditions on the produced nanoparticles was investigated. It was shown that different annealing temperatures [...] result in very different low frequency Raman profiles. [...] The forth chapter reports on the exploration of the possible use of the low frequency inelastic light scattering probe in the characterization of large viruses, as illustrated in the third chapter for small nanoparticles. In order to address the change of the light selection rules as the wavelength of the exciting light becomes comparable to the size of the nanoparticles, the behaviors of the viruses are compared to those of polymer colloids. Ultra Small Angle X-ray Scattering and Atomic Force Microscopy are used to first ensure the comparableness of viruses and polystyrene colloids in terms morphologies. On the basis of the inelastic light scattering data obtained for PS colloids [...], we discuss the difficult interpretation in termsof eigenmodes of the virus counterparts.
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Vernaz-Gris, Pierre. "Preparation of large cold atomic ensembles and applications in efficient light-matter interfacing." Thesis, Sorbonne université, 2018. http://www.theses.fr/2018SORUS060/document.
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Cette thèse de doctorat en co-tutelle a été centrée sur des expériences d’optique quantique faisant intervenir de grands ensembles atomiques. L’étude de l’interaction entre la lumière et la matière et l’augmentation de leur couplage dans ces systèmes sont des étapes fondamentales pour le développement et l’amélioration de protocoles de génération, de stockage et de manipulation d’information quantique. Le travail de thèse exposé ici traite en particulier de l’évolution des techniques de préparation d’ensembles atomiques denses, des protocoles de lumière arrêtée et de lumière stationnaire développés et étudiés expérimentalement. Les ensembles d’atomes froids préparés par refroidissement laser dans les deux réalisations expérimentales ont été portés jusqu’à des épaisseurs optiques de plusieurs centaines, à des températures d’une dizaine de microkelvin. De plus, l’adressage de ces ensembles dans des configurations symétriques ont permis l’étude de protocoles basés sur le renversement temporel de la conversion de lumière en excitations atomiques collectives. Ces améliorations ont mené au stockage de bits quantiques par transparence induite électromagnétiquement, et de lumière cohérente par symétrie temporelle dans une mémoire Raman, tous deux à des record d’efficacité, à de plus de 50%. Ce travail a également conduit à l’étude expérimentale de la lumière stationnaire et de nouveaux protocoles en découlant<br>This cotutelle PhD thesis revolves around quantum optics experiments which involve large atomic ensembles. The study of light-matter interaction and its enhancement are crucial steps in the development and progress of quantum information generation, storage and processing protocols. The work presented here focuses on the evolution of large atomic ensemble preparation techniques, on the development and experimental investigation of stopped and stationary light protocols. Laser-cooled atomic ensembles in both experimental realisations have been brought to optical depths of a few hundreds, at temperatures of tens of microkelvin. Moreover, addressing these ensembles in symmetric configurations has enabled the study of protocols based on the temporal reversal of the mapping of light to collective atomic excitations. These enhancements have led to the storage of qubits based on electromagnetically-induced transparency, and the optical storage in a backward-retrieval Raman scheme, both demonstrating efficiency records, above 50%. This work has also led to the experimental investigation of stationary light and new protocols based on it
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El, Alami Amal. "Mise en oeuvre de biocapteurs en vue de la détection de pesticides dans l'eau par diffusion Raman exaltée." Thesis, Le Mans, 2017. http://www.theses.fr/2017LEMA1010/document.
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La diffusion Raman exaltée de surface (SERS) est utilisée pour la mise au point d’un biocapteur capable de détecter des pesticides dans l’eau, en se basant sur le suivi de l’activité enzymatique de l’Acétylcholinestérase (ACHE). Les nanoparticules d’or sont utilisées comme substrats SERS actifs. Le signal Raman exalté de l’analyte est optimisé en testant plusieurs types de nanoparticules.Le Raman SERS a permis la détection directe du Paraoxon (PO) et du carbaryl (CA) et la possibilité de suivi de l’activité de l’ACHE. En absence d'inhibiteurs, la molécule d’acétylcholine (ATC) est transformée en acide acétique et en choline par l’enzyme ACHE. La mesure de l’activité de l’ACHE repose sur le suivi des concentrations en ATC car sa transformation est inhibée en présence de pesticides. Il a été ainsi possible d’établir une relation linéaire entre la concentration de pesticides et l’exaltation du signal Raman de l’ATC non transformé. La méthode a permis la détection du PO et du CA, avec une limite de détection beaucoup plus faible que la détection directe. Ce biocapteur basé sur l’activité de l’ACHE a ensuite été utilisé pour l'évaluation d’autres polluants (inhibiteurs d’ACHE) comme les additifs contenus dans les plastiques notamment. Enfin, nous avons développé une seconde approche qui consistait à mesurer l’activité de l’ACHE en utilisant la diffusion dynamique de la lumière. En effet, nous avons montré que les paramètres physicochimiques (agrégation) des AuNPs en contact avec certaines molécules, sont fortement influencés par l’activité enzymatique de l’ACHE. C’est ce phénomène d’instabilité qui nous a permis de distinguer entre les deux cas : absence et présence de PO<br>Surface-enhanced Raman scattering (SERS) was used to develop a biosensor for the detection of pesticides through the monitoring of the enzymatic activity of acetylcholinesterase (ACHE). Gold nanoparticles (AuNPs) were used as an active SERS substrate. The enhanced Raman signal of the analyte is optimized by testing several types of nanoparticles. Raman SERS allowed the direct detection of Paraoxon (PO) and carbaryl (CA) pesticides and the possibility of follow-up of the activity of the ACHE. In the absence of inhibitors, the acetylcholine (ATC) is transformed into acetic acid and choline by the enzyme ACHE. The measurement of ACHE activity is performed through the monitoring of ATC concentrations because its transformation is inhibited in the presence of pesticides. Results showed a linear correlation between the concentration of pesticides and the SERS signal of the untransformed ATC. The method was optimized for the quantification of paraoxon and carbaryl with a limit of quantification much lower than the one obtained with a direct detection. Their identification was also possible using chemometrics. This biosensors, based on the ACHE activities, was applied to the evaluation of emergent pollutants: additives of commercial polymers. Our results suggested that most of the tested polymers contained molecules that act as inhibitors of the ACHE. Finally, we propose another very simple approach to measure the ACHE activity using dynamic light scattering measurements. We found that the physicochemical parameters (aggregation) of AuNPs were strongly influenced by the enzymatic activity of ACHE when in contact with specified molecules, allowing to detect the presence of PO
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Marshall, Bruce Russell. "Raman scattering in ocean water." 1989. http://catalog.hathitrust.org/api/volumes/oclc/24084207.html.
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Yu-Chien, Chou. "Light Emission from Si Nanowires by Raman Effect." 2006. http://www.cetd.com.tw/ec/thesisdetail.aspx?etdun=U0016-1303200709322286.
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Chou, Yu-Chien, and 周佑謙. "Light Emission from Si Nanowires by Raman Effect." Thesis, 2006. http://ndltd.ncl.edu.tw/handle/60931639225325733689.
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碩士<br>國立清華大學<br>材料科學工程學系<br>94<br>Silicon-based optical devices have been attracting people’s eyes recently because it can totally revolutionize the bottleneck in today’s IC fabrication industry due to diminishing dimension of component by using photons instead of electrons as data carrier and create a pioneering avenue toward photonic generation. Latterly, some investigating groups successfully demonstrated the first all-silicon laser based on Raman scattering and exhibited as a forerunner for us. In behalf of breaking through several drawbacks as well as ameliorating the performance compared with the previous work, we utilize specific qualities of one-dimensional nanomaterials as backbone to construct silicon nanowires-based optical devices. Therefore, in this thesis we introduce several different growth mechanisms of nanowires and successful synthesize silicon nanowires via diverse fabrication processes in order to optimize the morphology of samples, meanwhile, investigate influence from different experimental parameters. Besides, we further examine unique physical and optical characteristics of silicon nanowires dependent on shape, diameter or orientation occurred from variation of different fabrication processes. In conclusion, we prove that one dimension silicon nanowires indeed promote poor light emission in bulk silicon and achieve better controllability though adequate fabrication process. In the future, we will expect to actualize the lasing effect and further carry out active multifarious optical devices, even realizing a silicon nanowires based optical circuit within one single chip.
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"Silicon planar lightwave circuits: raman amplification and polarization processing." 2004. http://library.cuhk.edu.hk/record=b6073665.
Texte intégralRésumé :
Liang Tak-keung.<br>"June 2004."<br>Thesis (Ph.D.)--Chinese University of Hong Kong, 2004.<br>Includes bibliographical references.<br>Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web.<br>Mode of access: World Wide Web.<br>Abstracts in English and Chinese.
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洪韻婷. "Enhancement and Control of Nanoscale Light-Matter InteractionPart 1: Study of Surface Enhanced Raman Effect of Self-Assembled Gold Nanoparticles Part 2: Mode Conversion in Plasmonic Nanocircuits." Thesis, 2012. http://ndltd.ncl.edu.tw/handle/80165493808639739895.
Texte intégralRésumé :
碩士<br>國立清華大學<br>化學系<br>100<br>Surface enhanced Raman spectroscopy (SERS) has ultrahigh sensitivity and is now wide used. SERS makes use of rough metal surfaces or metallic nanoparticles to enhance the Raman scattering of a specimen. However, the mechanism of the enhancement effect is still open to question. Thus, in the first part of the thesis, we try to study and compare the SERS signals from thiophenol molecules attached to self-assembled gold nanoparticles with distinct shape, size and facet. We also make an assumption to explain the experimental data from the aspect of electromagnetic theory by analyzing the near-field intensity of gold nanoparticles and chemical effect by calculating the surface area of gold nanoaprticles and binding energies of thiophenol molecules adsorbed on different crystal facets. We discovered that rhombic dodecahedron gold nanoparticles with facet have the largest Raman scattering intensity and the comparative SERS intensities predicted by theoretical calculations also consist with the experimental data. This research provides a criterion of choosing SERS-active substrates hereafter.
Besides, for the sake of controlling the interaction between light with matter, we propose and design mode converters in a plasmonic nanocircuit by manipulating the phase of surface plasmon on TWTL to achieve passive or active control of the guided modes and then it is capable of controlling the impedance of the optical field. Hence, it offers the possibility to handle nanoscale light-matter interaction. The mode conversion transforms successfully at will between transverse magnetic (TM) mode and transverse electric (TE) mode by means of differing in the path length or cross section between two wires as well as the surrounding refractive index. To realize the mode converters and monitor the optical phenomena, I build up an optical system containing a home-made confocal laser scanning microscope and a near-field scanning microscope.
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Sete, Eyob Alebachew. "Quantum Coherence Effects in Novel Quantum Optical Systems." Thesis, 2012. http://hdl.handle.net/1969.1/ETD-TAMU-2012-08-11400.
Texte intégralRésumé :
Optical response of an active medium can substantially be modified when coherent superpositions of states are excited, that is, when systems display quantum coherence and interference. This has led to fascinating applications in atomic and molecular systems. Examples include coherent population trapping, lasing without inversion, electromagnetically induced transparency, cooperative spontaneous emission, and quantum entanglement.
We study quantum coherence effects in several quantum optical systems and find interesting applications. We show that quantum coherence can lead to transient Raman lasing and lasing without inversion in short wavelength spectral regions--extreme ultraviolet and x-ray--without the requirement of incoherent pumping. For example, we demonstrate transient Raman lasing at 58.4 nm in Helium atom and transient lasing without inversion at 6.1 nm in Helium-like Boron (triply-ionized Boron). We also investigate dynamical properties of a collective superradiant state prepared by absorption of a single photon when the size of the sample is larger than the radiation wavelength. We show that for large number of atoms such a state, to a good approximation, decays exponentially with a rate proportional to the number of atoms. We also find that the collective frequency shift resulting from repeated emission and reabsorption of short-lived virtual photons is proportional to the number of species in the sample. Furthermore, we examine how a position-dependent excitation phase affects the evolution of entanglement between two dipole-coupled qubits. It turns out that the coherence induced by position-dependent excitation phase slows down the otherwise fast decay of the two-qubit entanglement. We also show that it is possible to entangle two spatially separated and uncoupled qubits via interaction with correlated photons in a cavity quantum electrodynamics setup. Finally, we analyze how quantum coherence can be used to generate continuous-variable entanglement in quantum-beat lasers in steady state and propose possible implementation in quantum lithography.