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Dissertations / Theses on the topic 'Molecular Photonics'
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1
Gray, David. "Molecular organic photonics." Thesis, Durham University, 1994. http://etheses.dur.ac.uk/5593/.
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The work presented in this thesis is derived from experimentation in the field of molecular organic photonics. This is done from the standpoint that devices cannot be understood without recourse to the molecular properties and vice versa. A background of nonlinear optics and a brief introduction to the origins of molecular organic nonlinearity is given to aid understanding of the main points of the argument. The dipole moment of several organics was calculated using a simple capacitance method which has been successfully applied to reactive species. These dipole moment results were necessary in the extraction of βʷ from the µβʷ extracted from the EFISH technique. This experiment was performed at 1.064µm and 1.907µm with the latter wavelength being applied to the first in a new class of organic molecules. Results of the work on a number of techniques relevant to thin film devices are also presented. This culminated in an amplitude modulator case study that brought all the techniques together. Finally a discussion on the links between molecular and device related properties justifies the approach taken.
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Keogh, Gary Peter. "The application of coherent Raman scattering to molecular photonics." Thesis, Imperial College London, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.243375.
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McKee, Erik. "Femtosecond Filament Interaction as a Probe for Molecular Alignment." Master's thesis, University of Central Florida, 2013. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/5991.
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Femtosecond laser filamentation is a highly nonlinear propagation mode. When a laser pulse propagates with a peak power exceeding a critical value Pcr (5 GW at 800 nm in air), the Kerr effect tends to collapse the beam until the intensity is high enough to ionize the medium, giving rise to plasma defocusing. A dynamic competition between these two effects takes place leaving a thin and weakly ionized plasma channel in the trail of the pulse.
When an ultrafast laser pulse interacts with molecules, it will align them, spinning them about their axis of polarization. As the quantum rotational wave packet relaxes, the molecules will experience periodic field-free alignment. Recent work has demonstrated the effect of molecular alignment on laser filamentation of ultra-short pulses. Revival of the molecular alignment can modify filamentation parameters as it can locally modify the refractive index and the ionization rate. In this thesis, we demonstrate with simulations and experiments that these changes in the filament parameters (collapse distance and filament plasma length) can be used to probe molecular alignment in CO2.M.S.
Masters
Optics and Photonics
Optics and Photonics
Optics
4
Liu, Yuan. "Development of laser spectroscopy for elemental and molecular analysis." Doctoral diss., University of Central Florida, 2013. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/5978.
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Laser-Induced Breakdown Spectroscopy (LIBS) and Raman spectroscopy are still growing analytical and sensing spectroscopic techniques. They significantly reduce the time and labor cost in analysis with simplified instrumentation, and lead to minimal or no sample damage. In this dissertation, fundamental studies to improve LIBS analytical performance were performed and its fusion with Raman into one single sensor was explored.
On the fundamental side, Thomson scattering was reported for the first time to simultaneously measure the electron density and temperature of laser plasmas from a solid aluminum target at atmospheric pressure. Comparison between electron and excitation temperatures brought insights into the verification of local thermodynamic equilibrium condition in laser plasmas.
To enhance LIBS emission, Microwave-Assisted LIBS (MA-LIBS) was developed and characterized. In MA-LIBS, a microwave field extends the emission lifetime of the plasma and stronger time integrated signal is obtained. Experimental results showed sensitivity improvement (more than 20-fold) and extension of the analytical range (down to a few tens of ppm) for the detection of copper traces in soil samples.
Finally, laser spectroscopy systems that can perform both LIBS and Raman analysis were developed. Such systems provide two types of complimentary information – elemental composition from LIBS and structural information from Raman. Two novel approaches were reported for the first time for LIBS-Raman sensor fusion: (i) an Ultra-Violet system which combines Resonant Raman signal enhancement and high ablation efficiency from UV radiation, and (ii) a Ti:Sapphire laser based NIR system which reduces the fluorescence interference in Raman and takes advantage of femtosecond ablation for LIBS.Ph.D.
Doctorate
Optics and Photonics
Optics and Photonics
Optics
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Jemli, Khaoula. "Synthése et auto-assemblage de molécules de pérovskite pour la photonique et le marquage." Thesis, Université Paris-Saclay (ComUE), 2016. http://www.theses.fr/2016SACLN009/document.
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Cette thèse s’inscrit dans la conjoncture actuelle de la recherche et du développement des matériaux pour les énergies renouvelables et dispositifs optoélectroniques à bas coût. Nous avons développées des nouveaux matériaux de pérovskites 2D et 3D afin d’exploiter leurs propriétés originales dans le but de les intégrer dans un second temps dans des dispositifs photoniques et photovoltaïques. Le travail d’ingénierie moléculaire sur la flexibilité des pérovskites 2D a permis de moduler le gap optique, d’extraire des informations sur les propriétés excitonique ainsi que l’activation de la photoluminescence. Quant à la flexibilité de la mise en forme des nouvelles pistes ont été initiées. L’étude de cette pérovskite 3D spécialement MAPI est très utile pour les applications photovoltaïques. La connaissance des propriétés optiques, structurales et de transport est une clé majeure pour l’augmentation des rendements et la stabilité de ces cellulesThis thesis is involved in the current situation of research and development of materials for renewable energy and optoelectronic devices at low cost.We have developed new 2D and 3D perovskite materials to exploit their unique properties in order to integrate them in a second time in photonic and photovoltaic devices. The molecular engineering work on flexibility perovskites 2D allowed to modulate the optical gap, to extract information about the properties excitonqiue as well as activation of the photoluminescence. As to the flexibility of the layout of the new tracks were initiated.The study of this 3D perovskite especially MAPI is very useful for photovoltaic applications. The knowledge of the optical properties, structural and transport is a major key to increased yields and stability of these cells
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McDougall, Craig. "Advanced photonic methodologies for the 'in vitro' manipulation of cellular systems." Thesis, University of St Andrews, 2011. http://hdl.handle.net/10023/1876.
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This thesis investigates the application of a variety of optical techniques for the manipulation of single cells and their local micro-environment. The methodologies developed provide enhanced control over a single cell under study affording exquisite spatial and temporal control over biological processes of interest. The work presented within the thesis can be split into three distinct categories. The first of these provides an investigation in light activated “caged” molecular probes. This work generated several new compounds which were then applied to providing control over processes involved in pain, mitochondrial intracellular signalling and memory processes in the central nervous system. Application of caged neurotransmitters then demonstrates the first in vitro wavelength orthogonal photolysis of biologically relevant substances. Such a technique has great potential in the study of fundamental interactions within the processes underpinning memory and cognitive function. Secondly the application of optical injection techniques for the introduction of membrane impermeable species of interest is presented. An exploration of laser sources and optical systems has yielded two new strategies for optical injection. The targeted introduction of fluorescent stains, nucleic acids and gold nanoparticles to the interior of live mammalian cells demonstrates the power of these techniques. Thirdly, an investigation in optical trapping and optical injection provides simplified micromanipulation techniqes for application to biological studies. The use of capillaries as reservoirs for reagents of interest has realised a procedure for the reduction of large-scale chemical assays to a single cell level in static flow. When this technique is combined with intelligent control over the trapping laser source’s temporal behaviour, the interaction with the sample under study can be tailored for biological amiability or sample ablation. In this way a single laser source can be employed for the optical trapping and nanosurgery of a biological sample. A final study is presented demonstrating initial results for the targeted optical injection of caged compounds into mammalian cells. This methodology draws on the strengths of optical injection and caging technologies and presents a significant step forward in the level of control afforded over a biological system under study by optical techniques. The studies presented highlight the level of control and flexibility afforded by the application of optical manipulation and excitation strategies. Such optical methodologies extend the photonic tools available for enhanced studies in the life sciences.
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Zandbergen, Sander, and Sander Zandbergen. "Light-Matter Interactions in Various Semiconductor Systems." Diss., The University of Arizona, 2017. http://hdl.handle.net/10150/624528.
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Semiconductors provide an interesting platform for studying light-matter interactions due to their unique electrically conductive behavior which can be deliberately altered in useful ways with the controlled introduction of confinement and doping, which changes the electronic band structure. This area of research has led to many important fundamental scientific discoveries that have in turn spawned a plethora of applications in areas such as photonics, microscopy, single-photon sources, and metamaterials. Silicon is the prevalent semiconductor platform for microelectronics because of its cost and electrical properties, while III-V materials are optimal for optoelectronics because of the ability to engineer a direct bandgap and create versatile heterojunctions by growing binary, ternary, or quaternary compounds.
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Konrad, Alexander [Verfasser], and Alfred J. [Akademischer Betreuer] Meixner. "Nano-photonics on luminescent molecular systems and metal particles in optical sub-wavelength microresonators / Alexander Konrad ; Betreuer: Alfred J. Meixner." Tübingen : Universitätsbibliothek Tübingen, 2016. http://d-nb.info/1198122153/34.
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Beaudoin, Bertrand Julien. "Homodyne High-harmonic Spectroscopy: Coherent Imaging of a Unimolecular Chemical Reaction." Thèse, Université d'Ottawa / University of Ottawa, 2012. http://hdl.handle.net/10393/23173.
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At the heart of high harmonic generation lies a combination of optical and collision physics entwined by a strong laser field. An electron, initially tunnel-ionized by the field, driven away then back in the continuum, finally recombines back to rest in its initial ground state via a radiative transition. The emitted attosecond (atto=10^-18) XUV light pulse carries all the information (polarization, amplitude and phase) about the photorecombination continuum-to-ground transition dipolar field. Photorecombination is related to the time-reversed photoionization process. In this perspective, high-harmonic spectroscopy extends well-established photoelectron spectroscopy, based on charged particle detection, to a fully coherent one, based on light characterization. The main achievement presented in this thesis is to use high harmonic generation to probe femtosecond (femto=10^-15) chemical dynamics for the first time. Thanks to the coherence imposed by the strong driving laser field, homodyne detection of attosecond pulses from excited molecules undergoing dynamics is achieved, the signal from unexcited molecules acting as the reference local oscillator. First, applying time-resolved high-harmonic spectroscopy to the photodissociation of a diatomic molecule, Br2 to Br + Br, allows us to follow the break of a chemical bond occurring in a few hundreds of femtoseconds. Second, extending it to a triatomic (NO2) lets us observe both the previously unseen (but predicted) early femtosecond conical intersection dynamics followed by the late picosecond statistical photodissociation taking place in the reaction NO2 to NO + O. Another important realization of this thesis is the development of a complementary technique to time-resolved high-harmonic spectroscopy called LAPIN, for Linked Attosecond Phase INterferometry. When combined together, time-resolved high-harmonic spectroscopy and LAPIN give access to the complex photorecombination dipole of aligned excited molecules. These achievements lay the basis for electron recollision tomographic imaging of a chemical reaction with unprecedented angstrom (1 angstrom= 0.1 nanometer) spatial resolution. Other contributions dedicated to the development of attosecond science and the generalization of high-harmonic spectroscopy as a novel, fully coherent molecular spectroscopy will also be presented in this thesis.
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Clavel, Michael Brian. "Tensile-Strained Ge/InₓGa₁₋ₓAs Heterostructures for Electronic and Photonic Applications." Thesis, Virginia Tech, 2015. http://hdl.handle.net/10919/78129.
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The continued scaling of feature size in silicon (Si)-based complimentary metal-oxide-semiconductor (CMOS) technology has led to a rapid increase in compute power. Resulting from increases in device densities and advances in materials and transistor design, integrated circuit (IC) performance has continued to improve while operational power (VDD) has been substantially reduced. However, as feature sizes approach the atomic length scale, fundamental limitations in switching characteristics (such as subthreshold slope, SS, and OFF-state power dissipation) pose key technical challenges moving forward. Novel material innovations and device architectures, such as group IV and III-V materials and tunnel field-effect transistors (TFETs), have been proposed as solutions for the beyond Si era. TFETs benefit from steep switching characteristics due to the band-to-band tunneling injection of carriers from source to channel. Moreover, the narrow bandgaps of III-V and germanium (Ge) make them attractive material choices for TFETs in order to improve ON-state current and reduce SS. Further, Ge grown on InₓGa₁₋ₓAs experiences epitaxy-induced strain (ε), further reducing the Ge bandgap and improving carrier mobility. Due to these reasons, the ε-Ge/InₓGa₁₋ₓAs system is a promising candidate for future TFET architectures. In addition, the ability to tune the bandgap of Ge via strain engineering makes ε-Ge/InₓGa₁₋ₓAs heterostructures attractive for nanoscale group IV-based photonics, thereby benefitting the monolithic integration of electronics and photonics on Si. This research systematically investigates the material, optical, and heterointerface properties of ε-Ge/InₓGa₁₋ₓAs heterostructures on GaAs and Si substrates. The effect of strain on the heterointerface band alignment is comprehensively studied, demonstrating the ability to modulate the effective tunneling barrier height (Ebeff) and thus the threshold voltage (VT), ON-state current, and SS in future ε-Ge/InₓGa₁₋ₓAs TFETs. Further, band structure engineering via strain modulation is shown to be an effective technique for tuning the emission properties of Ge. Moreover, the ability to heterogeneously integrate these structures on Si is demonstrated for the first time, indicating their viability for the development of next-generation high performance, low-power logic and photonic integrated circuits on Si.Master of Science
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Ruiz, Tórtola Ángela. "Desarrollo de biosensores nanofotónicos de alta sensibilidad para la detección de biomarcadores microRNA en aplicaciones de diagnóstico médico." Doctoral thesis, Universitat Politècnica de València, 2021. http://hdl.handle.net/10251/172631.
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[ES] El interés en desarrollar biosensores de alta sensibilidad para identificar y cuantificar una amplia gama de moléculas ha aumentado notablemente durante las últimas décadas en numerosos campos de aplicación. Entre ellos probablemente el más demandado sea el diagnóstico médico, el cual ha sido impulsado por el descubrimiento de nuevos biomarcadores de enfermedades, tales como los miRNAs. No obstante, la mayoría de las técnicas existentes para realizar la detección requieren el uso de marcadores debido a la falta de sensibilidad para detectar analitos en bajas concentraciones. Las estructuras ópticas basadas en campo evanescente, donde la luz es usada para transformar interacciones bioquímicas en variaciones de las señales ópticas, constituyen una interesante alternativa para el desarrollo de este tipo de biosensores sin la necesidad de utilizar marcadores (label-free). Concretamente las estructuras fotónicas integradas en tecnología Silicon On Insulator exhiben alta sensibilidad, bajo límite de detección y alto nivel de multiplexación en aplicaciones de detección, especialmente cuando se utilizan materiales y procesos basados en silicio y compatibles con CMOS.
En esta Tesis Doctoral se muestra el desarrollo de un biosensor fotónico integrado label-free para la detección de oligonucleótidos, y más concretamente biomarcadores de cáncer miRNAs. Este biosensor está basado en la combinación de estructuras de band gap fotónico y la inmovilización de sondas de tipo molecular beacon sobre su superficie. La combinación de sendos elementos de transducción y bioreconomiento ha proporcionado una elevada sensibilidad en la detección de oligonucleótidos manteniendo un footprint por debajo de 100 µm2. El uso de este biosensor fotónico ha permitido también estudiar experimentalmente una novedosa técnica de amplificación de detección. Esta técnica explota el cambio conformacional sufrido por la sonda molecular beacon tras la hibridación con su oligonucleótido complementario, permitiendo alejar una partícula/molécula de la superficie del sensor, lo cual podría ser utilizado para amplificar la respuesta de detección del sensor.
Finalmente se propone una estrategia de regeneración en línea de los biosensores nanofotónicos desarrollados mediante una estrategia química basada en el uso de formamida. Esta estrategia no solo permite ahorrar tiempo sino que también reduce la variación entre las medidas obtenidas en experimentos diferentes, siendo especialmente útil cuando se testean niveles similares de analito.[CA] L'interés en desenvolupar biosensors d'alta sensibilitat per a identificar i quantificar una àmplia gamma de molècules ha augmentat notablement durant les últimes dècades en nombrosos camps d'aplicació. Entre ells probablement el més demandat siga el diagnòstic mèdic, el qual ha sigut impulsat pel descobriment de nous biomarcadors de malalties, com ara els miRNAs. No obstant això, la majoria de les tècniques existents per a realitzar la detecció requereixen l'ús de marcadors a causa de la falta de sensibilitat per a detectar anàlits en baixes concentracions. Les estructures òptiques basades en camp evanescent, on la llum és usada per a transformar interaccions bioquímiques en variacions dels senyals òptics, constitueixen una interessant alternativa per al desenvolupament d'aquesta tipus de biosensors sense la necessitat d'utilitzar marcadors (label-free). Concretament les estructures fotòniques integrades en tecnologia Silicon On Insulator exhibeixen alta sensibilitat, baix límit de detecció i alt nivell de multiplexació en aplicacions de detecció, especialment quan s'utilitzen materials i processos basats en silici i compatibles amb CMOS. En aquesta Tesi Doctoral es mostra el desenvolupament d'un biosensor fotònic integrat label-free per a la detecció d'oligonucleòtids, i més concretament biomarcadors de càncer miRNAs. Aquest biosensor està basat en la combinació d'estructures de band gap fotònic i la immobilització de sondes de tipus molecular beacon sobre la seua superfície. La combinació d'ambdós elements de transducció i bioreconeixement ha proporcionat una elevada sensibilitat en la detecció d'oligonucleòtids mantenint un footprint per davall de 100 µm². L'ús d'aquest biosensor fotònic ha permés també estudiar experimentalment una nova tècnica d'amplificació de detecció. Aquesta tècnica explota el canvi conformacional patit per la sonda molecular beacon després de la hibridació amb el seu oligonucleòtid complementari, permetent allunyar una partícula/molècula de la superfície del sensor, la qual cosa podria ser utilitzada per amplificar la resposta de detecció del sensor. Finalment es proposa una estratègia de regeneració en línia dels biosensors nanofotònics desenvolupats mitjançant una estratègia química basada en l'ús de formamida. Aquesta estratègia no sols permet estalviar temps sinó que també redueix la variació entre les mesures obtingudes en experiments diferents, sent especialment útil quan es testen nivells similars d'anàlit.
[EN] The interest in developing highly sensitive biosensors to identify and quantify a wide range of molecules has remarkably been increasing during the last decades in numerous application fields. Among them, medical diagnosis is probably the most demanded, which has been driven by the discovery of new biomarkers of diseases, such as miRNAs. However, most of the existing techniques to perform the detection require the use of labels due to the lack of sensitivity to detect analytes at low concentrations. Evanescent-wave optical structures, where light is used to transduce biochemical interactions into variations of the optical signals, are an interesting alternative for the development of this type of biosensors allowing a label-free detection. Specifically, the planar integrated photonic structures based on Silicon On Insulator technology exhibit an extremely high sensitivity, a low detection limit and a high level of multiplexing in detection applications, especially when using materials and processes based on silicon and being CMOS compatible. This PhD Thesis is focused on the development of label-free integrated photonic biosensors for the detection of oligonucleotides, and more specifically miRNA cancer biomarkers. This biosensor is based on the combination of photonic band gap structures and the immobilization of molecular beacon probes on its surface. The combination of both transduction and biorecognition elements has provided a very high sensitivity towards the detection of target oligonucleotides while keeping a sensor footprint below 100 µm2. The use of this photonic biosensor also allowed the experimental study of a novel detection amplification technique. This technique exploits the conformational change suffered by the molecular beacon probe after hybridization with its complementary oligonucleotide, allowing the displacement of a particle/molecule away from the sensor surface, what might be used for amplifying the sensor's detection response. Finally, an online regeneration strategy for nanophotonic biosensors developed through a chemical strategy based on the use of formamide is proposed. This strategy not only saves time but also reduces the variation between measurements obtained in different experiments, being especially useful when testing similar levels of analyte.
Ruiz Tórtola, Á. (2021). Desarrollo de biosensores nanofotónicos de alta sensibilidad para la detección de biomarcadores microRNA en aplicaciones de diagnóstico médico [Tesis doctoral]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/172631
TESIS
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Omasta, Lukáš. "Příprava a charakterizace tenkých vrstev nízkomolekulárních materiálů pro organickou fotoniku." Master's thesis, Vysoké učení technické v Brně. Fakulta chemická, 2013. http://www.nusl.cz/ntk/nusl-216943.
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This diploma thesis is focused on characterization of properties of new organic materials with respect to its potential application in organic photonics. The theoretical part contains a themed literature research on low molecular thin films for organic photonics, mainly phthalocyanines together with description and structure of the photovoltaic energy conversion. The practical part includes the preparation of thin layers of selected organic materials for organic photonics. Prepared thin films were characterized by optical methods and current voltage characteristics. Based on these results, the thin films and structure of solar cells were optimalized. Acquired data were used to determine the materials and structures suitable for photonics applications.
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Wang, Yanhua. "Theoretical Design of Molecular Photonic Materials." Doctoral thesis, Stockholm: Bioteknologi, Kungliga Tekniska högskolan, 2007. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-4333.
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Kuczynski, Andrzej Piotr. "Zwitterionic materials for photonic applications." Thesis, Cranfield University, 1992. http://dspace.lib.cranfield.ac.uk/handle/1826/10405.
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A series of zwitterionic materials of general formula R-D*-CH=C(CN)- CÖH4-C(CN)2', where D* is a pyridirium or quinolinium acceptor and R is a hydrophobic alkyl chain or an aryl group, were deposited using the Langmuir- Blodgett (LB) technique and their photochromic and nonlinear optical properties characterised. The materials are highly solvatochromic, exhibiting a broad photochromic charge transfer band in the visible region which bleaches when irradiated. LB films of the zwitterions, Z-ß-(1-hexadecyl-4-pyridinium)-a-cyano-4- styryldicyanomethanide (CMH33-P3CNQ) and the quinolinium analogue, Z-ß-(1- hexadecyl-4-quinolinium)-a-cyano-4-styryldicyanomethanide (CIÖH33-Q3CNQ), are non-centrosymmetric (Z-type). They exhibit sharp charge transfer bands at 495 n ana ses n respecivey with haf widths ai half maximum of 27 and zz mi. Unusually, mixed LB films of CIGH33-P3CNQ and C161-133-Q3CNQ exhibit a single sharp charge transfer band whose position is dependent upon the mole fraction and is finely tunable in the range 495 to 565 nm. These films are photobleached when irradiated at wavelengths which overlap the absorption bands, and may find potential applications a components of a multifrequency optical memory. Also, the unique peak wavelength tuning of the heteromolecular films enabled the effect of the position of the absorption band on second harmonic generation to be investigated for the first time. The zwitterionic materials have exciting norlinear optical properties and the strongest second harmonic intensity from any LB film has been obtained. LB films of the quinolinium zwitterion (CMH33-Q3CNQ) are non-centrosymmetric and the second harmonic intensity increases quadratically with the number of layers deposited to thicknesses of ca. 1 m. It is one of only five known materials to show such behaviour and the second-order susceptibility (xa) = 180 pm V* at 1064 nm) is the highest value obtained for a multilayer structure.
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Hu, Honghua. "Third Order Nonlinearity of Organic Molecules." Doctoral diss., University of Central Florida, 2012. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/5310.
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The main goal of this dissertation is to investigate the third-order nonlinearity of organic molecules. This topic contains two aspects: two-photon absorption (2PA) and nonlinear refraction (NLR), which are associated with the imaginary and real part of the third-order nonlinearity (x3) of the material, respectively. With the optical properties tailored through meticulous molecular structure engineering, organic molecules are promising candidates to exhibit large third-order nonlinearities. Both linear (absorption, fluorescence, fluorescence excitation anisotropy) and nonlinear (Z-scan, two-photon fluorescence, pump-probe) techniques are described and utilized to fully characterize the spectroscopic properties of organic molecules in solution or solid-state form. These properties are then analyzed by quantum chemical calculations or other specific quantum mechanical model to understand the origins of the nonlinearities as well as the correlations with their unique molecular structural features. These calculations are performed by collaborators. The 2PA study of organic materials is focused on the structure-2PA property relationships of four groups of dyes with specific molecular design approaches as the following: (1) Acceptor-[pi]-Acceptor dyes for large 2PA cross section, (2) Donor-[pi]-Acceptor dyes for strong solvatochromic effects upon the 2PA spectra, (3) Near-infrared polymethine dyes for a symmetry breaking effect, (4) Sulfur-squaraines vs. oxygen-squaraines to study the role of sulfur atom replacement upon their 2PA spectra. Additionally, the 2PA spectrum of a solid-state single crystal made from a Donor-[pi]-Acceptor dye is measured, and the anisotropic nonlinearity is studied with respect to different incident polarizations. These studies further advance our understanding towards an ultimate goal to a predictive capability for the 2PA properties of organic molecules. The NLR study on molecules is focused on the temporal and spectral dispersion of the nonlinear refraction index, n2, of the molecules. Complicated physical mechanisms, originating from either electronic transitions or nuclei movement, are introduced in general. By adopting a prism compressor / stretcher to control the pulsewidth, an evolution of n2 with respect to incident pulsewidth is measured on a simple inorganic molecule –carbon disulfide (CS2) in neat liquid at 700 nm and 1064 nm to demonstrate the pulsewidth dependent nonlinear refraction. The n2 spectra of CS2 and certain organic molecules are measured by femtosecond pulses, which are then analyzed by a 3-level model, a simplified “Sum-over-states” quantum mechanical model. These studies can serve as a precursor for future NLR investigations.ID: 031001375; System requirements: World Wide Web browser and PDF reader.; Mode of access: World Wide Web.; Adviser: Eric W. Van Stryland.; Co-adviser: David J. Hagan.; Title from PDF title page (viewed May 21, 2013).; Thesis (Ph.D.)--University of Central Florida, 2012.; Includes bibliographical references (p. 213-226).
Ph.D.
Doctorate
Optics and Photonics
Optics and Photonics
Optics
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Neitzke, Oliver Björn. "On the Integration of Single Emitters in Solids and Photonic Nano-Structures." Doctoral thesis, Humboldt-Universität zu Berlin, 2018. http://dx.doi.org/10.18452/19119.
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Quantentechnologien sind im Begriff sich von Laborversuchen zu effizienten Anwendungen zu entwickeln. Die Quantenzustände einzelner Photonen spielen dabei die Rolle als Bindeglied zwischen stationären Quantensystemen. Ein hybrider Ansatz wird verfolgt, um die Wechselwirkung gezielt zwischen im Wellenleiter geleiteten Photonen und gekoppelten Quantenemittern zu erreichen.
Die Dissertation untersucht zwei zentrale Aspekte solcher hybriden photonischen Quantentechnologien: die effiziente Erzeugung von Photonen und die Optimierung von photonischen Strukturen.
Der erste Teil dieser Arbeit behandelt die Entwicklung einer optischen Mikrotechnology. Integrierte nano-photonische Wellenleiter aus Siliziumnitrid wurden für die Kopplung zu Quantenemittern entworfen, optimiert und optisch untersucht. Das finale Design wurde erfolgreich in Kopplungsexperimenten verwendet, bei denen 42 % der Fluoreszenz eines einzelnen Moleküls an einen Wellenleiter gekoppelt wurde.
Der zweite Teil der Arbeit untersucht zwei Einzelphotonenquellen. Zunächst wurde ein neuartiger Einzelphotonenemitter basierend auf Defektzentren in Zinkoxid optisch bei tiefen Temperaturen untersucht. Es konnte im Zuge dieser Arbeit erstmals gezeigt werden, dass die Photonen von nano-strukturiertem Zinkoxid sehr schmalbandige Emission aufweisen.
Im letzten Teil, wird eine Einzelphotonenquelle bestehend aus einem organischen Molekül untersucht. Bei kryogenen Temperaturen wurden Lebenszeit-limitierte Linienbreiten auf den Molekülproben detektiert. Die Rabi-Oszillationen zwischen den Molekülzuständen konnten akkurat durch eine quantenmechanische Theorie beschrieben werden, wodurch die Vermessung der Dephasierung des Quantensystems durch die nanoskopische Umgebung präzise studiert werden konnte.
Die Ergebnisse dieser Arbeit zur Kopplung von Einzelphotonenquellen stellen die Grundlage für weitere Anwendungen durch eine photonische Quantentechnologie dar.Quantum technologies are on the verge to transition from laboratory experiments to efficient integrated applications. The quantum states of photons are the connecting link between individual stationary quantum systems. A hybrid approach is employed to tailor the interaction of routed photons with optically coupled quantum systems. The thesis investigates two core aspects of a hybrid photonic quantum technology: efficient single photon generation and optimized photonic micro-structures, suitable to form a hybrid system. In the first part of this work, nano-photonic integrated structures were optimized for efficient coupling to quantum emitters. Optical waveguides based on silicon nitride (SiN) were designed, fabricated, and optically characterized. The final design was successfully employed in coupling experiments, where up to 42% of the fluorescence from a single molecule was coupled to a waveguide. In the second part of this thesis two single photon sources are investigated towards their implementation into a hybrid photonic system. First, a novel single photon source based on a defect center in zinc oxide was optically investigated at room-temperature and cryogenic temperature. Spectrally narrow zero-phonon lines of the fluorescence from nano-structured zinc oxide were measured for the first time during this work. A second emitter system, based on an organic dye molecule was investigated in the final part of this research. At cryogenic temperatures, single molecules showed lifetime-limited linewidths of <50MHz. A resonant laser source drives Rabi oscillations, which are accurately described by the quantum mechanical theory of a two-level system. The system's decoherence was mapped, illustrating the quantum sensing capabilities of the system. The results presented in this thesis on coupling efficiencies and single emitter performance provide the necessary background of the elements composing a future hybrid technology.
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Peceli, Davorin. "Absorptive and Refractive Optical Nonlinearities in Organic Molecules and Semiconductors." Doctoral diss., University of Central Florida, 2013. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/5687.
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The main purpose of this dissertation to investigate photophysical properties, third order nonlinearity and free carrier absorption and refraction in organic materials and semiconductors. Special emphasis of this dissertation is on characterization techniques of molecules with enhanced intersystem crossing rate and study of different approaches of increasing triplet quantum yield in organic molecules. Both linear and nonlinear characterization methods are described. Linear spectroscopic characterization includes absorption, fluorescence, quantum yield, anisotropy, and singlet-oxygen generation measurements. Nonlinear characterization, performed by picosecond and femtosecond laser systems (single and double pump-probe and Z-scan measurements), includes measurements of the triplet quantum yields, excited-state absorption, two-photon absorption, nonlinear refraction and singlet and triplet-state lifetimes. The double pump-probe technique is a variant of the standard pump-probe method but uses two pumps instead of one to create two sets of initial conditions for solving the rate equations allowing a unique determination of singlet- and triplet-state absorption parameters and transition rates. The advantages and limitations of the the double pump-probe technique are investigated theoretically and experimentally, and the influences of several experimental parameters on its accuracy are determined. The accuracy with which the double pump-probe technique determines the triplet-state parameters improves when the fraction of the population in the triplet state relative to the ground state is increased. Although increased accuracy is in principle achievable by increasing the pump fluence in the reverse saturable absorption range, it is shown that the DPP is optimized by working in the saturable absorption regime. Two different approaches to increase intersystem crossing rates in polymethine-like molecules are presented: traditional heavy atom substitution and molecular levels engineering. Linear and nonlinear optical properties of a series of polymethine dyes with Br- and Se- atoms substitution, and a series of new squaraine molecules, where one or two oxygen atoms in a squaraine bridge are replaced with sulfur atoms, are investigated. A consequence of the oxygen-to-sulfur substitution in squaraines is the inversion of their lowest lying ??' and n?' states leading to a significant reduction of singlet-triplet energy difference and opening of an additional intersystem channel of relaxation. Experimental studies show that triplet quantum yields for polymethine dyes with heavy-atom substitutions are small (not more than 10%), while for sulfur-containing squaraines these values reach almost unity. Experimental results are in agreement with density functional theory calculations allowing determination of the energy positions, spin-orbital coupling, and electronic configurations of the lowest electronic transitions. For three different semiconductors: GaAs, InP and InAsP two photon absorption, nonlinear refraction and free carrier absorption and refraction spectrums are measured using Z-scan technique. Although two photon absorption spectrum agrees with the shape of theoretical prediction, values measured with picosecond system are off by the factor of two. Nonlinear refraction and free carrier nonlinearities are in relatively good agreement with theory. Theoretical values of the third order nonlinearities in GaAs are additionally confirmed with femtosecond Z-scan measurements. Due to large spectral bandwidth of femtosecond laser, three photon absorption spectrum of GaAs was additionally measured using picosecond Z-scan. Again, spectral shape is in excellent agreement with theory however values of three photon absorption cross sections are larger than theory predicts. ?Ph.D.
Doctorate
Optics and Photonics
Optics and Photonics
Optics
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Hurenkamp, Johannes Henricus. "Tuning energy transfer between chromophores switchable molecular photonic systems /." [S.l. : [Groningen : s.n.] ; University Library Groningen] [Host], 2008. http://irs.ub.rug.nl/ppn/.
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Barêa, Luís Alberto Mijam 1982. "Moléculas fotônicas para aplicações em engenharia espectral e processamento de sinais ópticos." [s.n.], 2014. http://repositorio.unicamp.br/jspui/handle/REPOSIP/276994.
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Orientador: Newton Cesário FrateschiTese (doutorado) - Universidade Estadual de Campinas, Instituto de Física Gleb Wataghin
Made available in DSpace on 2018-08-24T10:26:52Z (GMT). No. of bitstreams: 1 Barea_LuisAlbertoMijam_D.pdf: 8459370 bytes, checksum: 5dd565986711cb06cb24cf63d6d69372 (MD5) Previous issue date: 2014
Resumo: Sistemas fotônicos baseados em ressonadores na forma de anéis tem uma dependência fundamental dada pela relação estreita entre espaçamento espectral livre (Free Spectral Range, FSR), fator de qualidade total, Q, e o raio dos ressonadores, R. Nesta tese, nós quebramos esta dependência empregando moléculas fotônicas (Photonic Molecules, PMs) baseadas em múltiplos anéis internamente acoplados a um anel externo, que por sua vez está acoplado a um guia de onda. Aplicando o método de matriz de transferência (Transfer-Matrix Method, TMM) e programas robustos de simulação, nós projetamos três tipos de PMs baseada em uma plataforma de Silício-sobre-isolante (Silicon-on-Insulator, SOI). Este projeto mostrou que o acoplamento entre duas ou mais micro-cavidades ópticas, permite separações espectrais e hibridização dos modos quando as frequências ressonantes estão degeneradas nas cavidades, similar ao acoplamento fraco entre átomos. Estas PMs foram fabricadas com um processo convencional e compatível com a tecnologia CMOS, empregando uma Foundry, e suas caracterizações mostraram a emergência de dupletos, tripletos, quadrupletos e sextupletos de ressonâncias degeneradas, com alto Q e espaçamentos curtos, somente possíveis com anéis de algumas ordens de magnitude maiores em área. Estes resultados quebraram o paradigma da interdependência entre Q, FSR e R, evidenciando que é possível ter tempo de vida fotônico, espaçamento espectral e área independentes. As aplicações destas PMs em processamento de sinal óptico também foram demonstrados neste trabalho. Nós apresentamos o uso da molécula com dupleto de ressonâncias para extrair um sinal RF de 34.2 GHz, filtrando as bandas laterais de um sinal modulado. Também foi demonstrado que moduladores ópticos ultracompactos operando à 2.75 vezes acima do limite da largura de linha do ressonador pode ser obtido a partir da PM que apresenta um tripleto de ressonâncias, separadas de ~55 GHz. Finalmente, utilizando a molécula que permite obter um quadrupleto de ressonâncias, foi demonstrado a conversão de comprimento de onda totalmente óptico (multicasting) para quatro canais convertidos e separados de 40-60 GHz, utilizando apenas 1 mW de potência de controle
Abstract: Photonic systems based on microring resonators have a fundamental constraint given by the strict relationship among free spectral range (FSR), total quality factor (Q) and resonator size (R). In this thesis, we break this dependence employing CMOS compatible photonic molecules (PMs) based on multiple inner ring resonators coupled to an outer ring, which is coupled to a straight bus waveguide. Applying the transfer matrix method (TMM) and simulation robust programs, we project three types of PM based on scalable silicon-on-insulator (SOI) platform. This project shows that the coupling between two or more optical micro-cavities, allows spectral splitting and hybridization of the modes when the resonant frequencies are degenerated in the cavities, similar to weak coupling between atoms. These PMs were fabricated in a conventional CMOS Foundry and your characterization shows the emergence of doublet, triplet, quadruplet and sextuplet of degenerated resonances, with high-Q and close-spaced, only achievable with single-ring orders of magnitude larger in footprint. These results break the paradigm of the interdependence between Q, FSR and R, evidencing that is possible to have photonic lifetime, spectral spacing and footprint independents. The applications of these PMs in optical processing signal were also demonstrate in this work. We demonstrate the use of the doublet splitting for 34.2 GHz RF signal extraction by filtering the sidebands of a modulated optical signal. We also demonstrate that very compact optical modulators operating 2.75 times beyond its resonator linewidth limit may be obtained using the PM triplet splitting, with separation of ~ 55 GHz. Finally, using the quadruplet of resonances, we demonstrate four-channel all-optical wavelength multicasting using only 1 mW of control power, with converted channel spacing of 40-60 GHz
Doutorado
Física
Doutor em Ciências
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Shirdel, Javid. "Photo-physical characterization of flavin-pyrene-phenothiazine molecular photonic complexes." [S.l.] : [s.n.], 2007. http://deposit.ddb.de/cgi-bin/dokserv?idn=985128062.
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Felip, León Carlos. "Molecular Nanoparticles and Gels: Materials for Biomedical and Photonic Applications." Doctoral thesis, Universitat Jaume I, 2018. http://hdl.handle.net/10803/587103.
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The general objective of the present thesis is the study and development of low molecular weight gelators with photonic and biomedical applications.
Low molecular weight gelators derived from amino acids containing fluorescent moieties will be synthesized and characterized.
The energy transfer process occurring on a stimuli-responsive orthogonal two-component gelator will be studied, paving the way for possible light-harvesting applications.
The construction of a smart versatile gel that present aggregation induced emission will be carried out. The aggregation mode showed to have crucial implications on the AIE phenomenon.
Miniaturization of macroscopic molecular gels in nano- and micro-objects will be carried out. Biomedical applications of this new systems will be assessed.
New hybrid materials containing molecular gels and upconverting nanoparticles will be studied. The energetic and structural relationship among them will be assessed resulting in potential applications in photodynamic therapy.
4-amino-1,8-naphthalimide chromophore in self-assembled systems will be studied as nitric oxide sensor.L'objectiu general de la tesi és l'estudi i desenvolupament de molècules de baix pes molecular que s'auto-assemblen per a ser utilitzades en aplicacions fotòniques i biomèdiques. Es sintetitzaran i caracteritzaran noves famílies de gelants de baix pes molecular derivats d'aminoàcids que tenen fraccions fluorescents. S'avaluarà el procés de transferència d'energia que es duu a terme en gels moleculars reversibles auto-assemblats com a possible símil de sistemes naturals. S'estudiarà la construcció d'un nou gel versàtil que respongui als estímuls i que sofreix fenòmens d'emissió induïts per agregació degut a l'auto-organització en fibres. S'estudia la miniaturització de gels moleculars macroscòpics en nano i microgels moleculars. Es realitzarà un estudi fonamental d'un nou material híbrid basat en les relacions estructurals i energètiques entre dues àrees d'interès: Els gels moleculars fluorescents i les nanopartícules de conversió ascendent. S'estudia el comportament del cromòfor 4-amino-1,8-naftalimida en sistemes autoensamblats com a sensor d'òxid nítric (NO).
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Fulop, Tiberiu G. "From Electrodeposited InSb to Photonic Crystals and Nanopatterned Molecular Templates." Case Western Reserve University School of Graduate Studies / OhioLINK, 2004. http://rave.ohiolink.edu/etdc/view?acc_num=case1089900004.
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Sands, Anita Mary. "The ionization and dissociation of selected molecules by VUV photons." Thesis, Queen's University Belfast, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.343088.
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Kim, Younggu. "Novel organic polymeric and molecular thin-film devices for photonic applications." College Park, Md. : University of Maryland, 2006. http://hdl.handle.net/1903/4164.
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Thesis (Ph. D.) -- University of Maryland, College Park, 2006.Thesis research directed by: Department of Electrical and Computer Engineering. Title from t.p. of PDF. Includes bibliographical references. Published by UMI Dissertation Services, Ann Arbor, Mich. Also available in paper.
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Gray, Tomoko O. "Exploitation of molecular mobilities for advanced organic optoelectronic and photonic nano-materials /." Thesis, Connect to this title online; UW restricted, 2007. http://hdl.handle.net/1773/9908.
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Stewart, Beverly. "Computational chemistry applied to the excited state decay of molecular photonic devices." Thesis, University of Newcastle Upon Tyne, 2010. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.538922.
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Ford, J. S. "Applied molecular quantum electrodynamics : geometric aspects of the efficiency of photonic interactions." Thesis, University of East Anglia, 2015. https://ueaeprints.uea.ac.uk/59366/.
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This thesis presents applications of molecular quantum electrodynamics (MQED) to the analysis of resonance energy transfer (RET), molecular absorption and emission, and light scattering by molecules. An MQED framework describes such processes as a series of microscopic photonic interaction events. Multi-interaction processes entail intermediate states of the system’s evolution remaining unspecified, requiring careful interpretation. RET, as modified by coupling with the nearest molecule of the surrounding refractive medium, is investigated. Special attention is given to a system geometry where unmodified RET is impossible, so coupling with the third chromophore is essential. Two distinct treatments are given to emission by a multi-chromophore system, distinguished by different ways of framing the quantum system: Either all photons are virtual and chromophores share excitation, or real photons interact with a single unspecified chromophore. Anomalously high fluorescence-anisotropy is explainable with the latter analysis. Off-resonant light is known to modify the absorption behaviour of molecules: This weak-interaction is analysed with an MQED formulation modified by field dressing, modelling advanced media effects in the condensed phase. Within the electric-dipole approximation, hyper-Rayleigh scattering (HRS) is considered forbidden for centrosymmetric molecules: By including higher-multipole interactions, mechanisms enabling conventionally-forbidden HRS are discovered. For each process analysed, the main results are predictions for the efficiency or observable rate. The relative positions and orientations of the molecules and fields are the key variables, so the rate equations are typically complicated functions thereof. Where rate equations depend on molecular orientation, it is often appropriate to calculate the average value over all orientations, giving results applicable to the fluid phase. System geometry may exert very fine control – a process forbidden in one case may become allowed by a minor change of one chromophore’s alignment. This thesis contributes to understanding the precise requirements of molecular geometry that must inform the design of energy-transfer systems.
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Jannasch, Anita. "High performance photonic probes and applications of optical tweezers to molecular motors." Doctoral thesis, Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2017. http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-103696.
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Optical tweezers are a sensitive position and force transducer widely employed in physics and biology. In a focussed laser, forces due to radiation pressure enable to trap and manipulate small dielectric particles used as probes for various experiments. For sensitive biophysical measurements, microspheres are often used as a handle for the molecule of interest. The force range of optical traps well covers the piconewton forces generated by individual biomolecules such as kinesin molecular motors. However, cellular processes are often driven by ensembles of molecular machines generating forces exceeding a nanonewton and thus the capabilities of optical tweezers. In this thesis I focused, fifirst, on extending the force range of optical tweezers by improving the trapping e fficiency of the probes and, second, on applying the optical tweezers technology to understand the mechanics of molecular motors. I designed and fabricated photonically-structured probes: Anti-reflection-coated, high-refractive-index, core-shell particles composed of titania. With these probes, I significantly increased the maximum optical force beyond a nanonewton. These particles open up new research possibilities in both biology and physics, for example, to measure hydrodynamic resonances associated with the colored nature of the noise of Brownian motion. With respect to biophysical applications, I used the optical tweezers to study the mechanics of single kinesin-8. Kinesin-8 has been shown to be a very processive, plus-end directed microtubule depolymerase. The underlying mechanism for the high processivity and how stepping is affected by force is unclear. Therefore, I tracked the motion of yeast (Kip3) and human (Kif18A) kinesin-8s with high precision under varying loads. We found that kinesin-8 is a low-force motor protein, which stalled at loads of only 1 pN. In addition, we discovered a force-induced stick-slip motion, which may be an adaptation for the high processivity. Further improvement in optical tweezers probes and the instrument will broaden the scope of feasible optical trapping experiments in the future.
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Rappe, Andrew Marshall. "AB initio theoretical studies of transition-metal, molecular, and photonic band-gap materials." Thesis, Massachusetts Institute of Technology, 1992. http://hdl.handle.net/1721.1/29861.
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Bradley, Thomas David. "Atomic vapours filled hollow core photonic crystal fibre for magneto-optical spectroscopy." Thesis, University of Bath, 2014. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.616871.
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This thesis describes developments in atomic vapour loading in hollow core photonic crystal fibre (HC-PCF) for fabrication of atomic vapour loaded photonic microcells (PMC). These developments have been targeted at addressing some of the issues associated with loading atomic vapours in confined waveguiding geometries such as increased dephasing and physio-chemical wall absorptions. Atomic vapour loaded HC-PCF and PMC’s have applications in laser metrology, coherent optics and magneto optical spectroscopy. State of the art HC-PCF have been fabricated for loading with atomic vapour including both photonic bandgap (PBG) guiding and inhibited coupling (IC) hypocycloidal core shape Kagome HC-PCF. Record loss of 70 dB/km has been achieved in IC hypocycloid core shape Kagome HC-PCF in the spectral region centred at 800 nm. This fibre retains excellent single mode propagation combined with large core and increased optical bandwidth in comparison with specialist PBG HC-PCF optimised for operation around 800 nm. Aluminosilicate sol-gel coatings have been developed and successfully applied to the inner core wall of HC-PCF’s to reduce the atomic vapour surface interaction. Confining atomic vapours in micron scaled HC-PCF results in increased dephasing rates because of the frequent atom wall collisions. Anti relaxation coating materials have been applied to the inner core wall and the longitudinal relaxation time has been measured in coated and uncoated fibres utilising a magneto optical technique. Additionally sub Doppler transparencies are investigated in anti relaxation coated and uncoated HC-PCF.
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Beyer, Griffin Joseph. "Large Area 2D Electronic Molecular Sensor Arrays via Photonic Annealing of Amorphous Sputtered Mos2." University of Dayton / OhioLINK, 2020. http://rave.ohiolink.edu/etdc/view?acc_num=dayton1582624657416084.
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Cognee, Kevin. "Hybridization of open photonic resonators." Thesis, Bordeaux, 2020. http://www.theses.fr/2020BORD0002.
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Le contrôle de l'interaction entre la lumière et la matière est d'une importance capitale dans de nombreuses technologies modernes, avec des applications allant de la détection, aux télécommunications et à l'information quantique. Les résonateurs nanophotoniques permettent d'améliorer cette interaction par le confinement et le stockage du champ lumineux.Cette thèse étudie l'hybridation des modes propres des nano et microrésonateurs, et en particulier les propriétés de résonateurs hybrides composés d'une cavité diélectrique et de nanoantennes plasmoniques. Les résonateurs photoniques présentent toujours des pertes, en particulier par rayonnement, et ainsi, ne peuvent être bien décrits que dans le cadre de la théorie des modes quasi-normaux (quasinormal modes - QNM). Nous confirmons la pertinence de telles théories en étudiant numériquement et expérimentalement la perturbation de cavités diélectriques à facteurs de qualité élevés.Ensuite, nous proposons une théorie permettant d’étudier l'hybridation de plusieurs résonateurs pour ainsi prédire les propriétés de l’ensemble. Dans le cas d’hybrides antenne-cavité, des travaux antérieurs ont démontré le grand potentiel de ce type de résonateurs pour améliorer l'interaction lumière-matière au-delà de ce qui accessible avec leurs composants pris individuellement. Nous montrons ici, par le biais de travaux théoriques et expérimentaux, que ces résonateurs offrent également des degrés de contrôle supplémentaires sur les propriétés de la lumière émise, telles que la directionnalité, ou encore l’émission d’ondes présentant un moment angulaire orbital pur. Enfin, nous étudions les performances de tels résonateurs hybrides dans le cadre de l'optomécanique moléculaire. En effet, nous montrons qu'ils constituent une excellente plateforme pour augmenter la diffusion Raman, tout en offrant des canaux d’excitation et d’émission dont les propriétés peuvent-être contrôlées, pour les signaux de pompe et RamanThe control of the interaction between light and matter is of paramount importance in many modern technologies, with applications ranging from sensing to telecommunication and quantum information. Nanophotonic resonators allow to enhance this interaction by the storage and confinement of the light field.This thesis studies the hybridization of eigenmodes of nano- and microresonators, and in particular the properties of hybrid resonators composed of a dielectric cavity and plasmonic nanoantennas. Due to their lossy nature, in particular radiation, photonic resonators can only be well described in the framework of quasinormal modes theory (QNM). We confirm the relevance of such theories by investigating the physics of the perturbation of high-Q dielectric cavities aided by numerical and experimental works.Then we propose a theory to study the hybridization of multiple resonators and predict the properties of the ensemble. In the context of antenna-cavity hybrids, previous works have demonstrated the great potential of such resonators to enhance light-matter interaction further than what is achieved with their components taken individually. Here we show, with theoretical and experimental works that such resonators also offer additional degrees of control over the properties of the emitted light, such as directionality or beams carrying a pure orbital angular momentum. We furthermore investigate the performances of such hybrid resonators in the context of molecular optomechanics. Indeed, we show they can be an excellent platform to enhance Raman scattering, while simultaneously offering input and output channels with controllable properties for the pump and Raman signals
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Flynn, John J. "Optimizing the Discovery and Processability of Biologically Derived Molecular Glass Host Materials for Photonic Applications." University of Dayton / OhioLINK, 2020. http://rave.ohiolink.edu/etdc/view?acc_num=dayton1588192751503223.
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Jones, Andrew Michael. "Realizing a mid-infrared optically pumped molecular gas laser inside hollow-core photonic crystal fiber." Diss., Kansas State University, 2012. http://hdl.handle.net/2097/13775.
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Doctor of PhilosophyDepartment of Physics
Kristan L. Corwin
This research has focused on the development, demonstration, and characterization of a new type of laser based on optically-pumped gases contained within hollow optical fibers. These novel lasers are appealing for a variety of applications including frequency metrology in the mid-infrared, free-space communications and imaging, and defense applications. Furthermore, because of the hollow core fibers used, this technology may provide the means to surpass the theoretical limits of output power available from high power solid-core fiber laser systems. Gas-filled hollow-core fiber lasers based on population inversion from acetylene ([superscript]12C[subscript]2H[subscript]2) and hydrogen cyanide (HCN) gas contained within the core of a kagome-structured hollow-core photonic crystal fiber have now been demonstrated. The gases are optically pumped via first order rotational-vibrational overtones near 1.5 μm using 1-ns duration pulses from a home-built optical parametric amplifier. Narrow-band laser emission peaks in the 3-μm region corresponding to the ΔJ = ±1 dipole allowed rotational transitions between the pumped vibrational overtone modes and the fundamental C-H stretching modes have been observed in both molecules. High gain resulting from tight confinement of the pump and laser light together with the active gas permits these lasers to operate in a single pass configuration, without the use of any external resonator structure. Studies of the generated mid-infrared pulse energy, threshold energy, and slope efficiency as functions of the launched pump pulse energy and gas pressure have been performed and show an optimum condition where the maximum laser pulse energy is achieved for a given fiber length. The laser pulse shape and the laser-to-pump pulse delay have been observed to change with varying pump pulse energy and gas pressure, resulting from the necessary population inversion being created in the gases at a specific fiber length dependent on the launched pulse energy. Work is on going to demonstrate the first continuous wave version of the laser which may be used to produce a single coherent output from many mutually incoherent pump sources.
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Marie, Héléne. "Elaboration of a new sensor based on molecularly imprinted polymers for the detection of molecules in physiological fluids." Phd thesis, Université de Technologie de Compiègne, 2013. http://tel.archives-ouvertes.fr/tel-00977390.
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This thesis aimed at elaborating an optical sensor to detect molecules in a biological fluid. Two steroids and a xenobiotic were identified as biomarkers released in some body fluids: cyproterone acetate, cortisol and 2,4-dichlorophenoxyacetic acid respectively. On one hand, detection was performed by Molecularly Imprinted Polymers (MIPs). These tailor-made synthetic receptors display numerous qualities that foster their integration in sensors. MIPs were therefore developed against the targeted analytes. Formulation optimization was led thanks to experimental designs. On the other hand, optical transduction was made possible thanks to the structuring of a polymer into a photonic crystal. Opals were manufactured with a new process suitable for large scales and were used to mold MIPs in inverse opals. Thus, submicron structures of the polymer are responsible for the color of the sensor. A change of color is triggered by the recognition of the analyte by the polymer (upon swelling). Polymers studied displayed sufficient swelling observed by spectrophotometry. Finally, the work of this thesis consisted in elaborating polymer formulations and their integration in a sensor so as to detect an analyte with direct, rapid and unobtrusive means.
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McBride, Patrick M. "The Effect of Polarization and InGaN Quantum Well Shape in Multiple Quantum Well Light Emitting Diode Heterostructures." DigitalCommons@CalPoly, 2012. https://digitalcommons.calpoly.edu/theses/822.
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Previous research in InGaN/GaN light emitting diodes (LEDs) employing semi-classical drift-diffusion models has used reduced polarization constants without much physical explanantion. This paper investigates possible physical explanations for this effective polarization reduction in InGaN LEDs through the use of the simulation software SiLENSe. One major problem of current LED simulations is the assumption of perfectly discrete transitions between the quantum well (QW) and blocking layers when experiments have shown this to not be the case. The In concentration profile within InGaN multiple quantum well (MQW) devices shows much smoother and delayed transitions indicative of indium diffusion and drift during common atomic deposition techniques (e.g. molecular beam epitaxy, chemical vapor deposition). In this case the InGaN square QW approximation may not be valid in modeling the devices' true electronic behavior. A simulation of a 3QW InGaN/GaN LED heterostructure with an AlGaN electron blocking layer is discussed in this paper. Polarization coefficients were reduced to 70% and 40% empirical values to simulate polarization shielding effects. QW shapes of square (3 nm), trapezoidal, and triangular profiles were used to simulate realistic QW shapes. The J-V characteristic and electron-hole wavefunctions of each device were monitored. Polarization reduction decreased the onset voltage from 4.0 V to 3.0 V while QW size reduction decreased the onset voltage from 4.0 V to 3.5 V. The increased current density in both cases can be attributed to increased wavefunction overlap in the QWs.
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Chamanzar, Maysamreza. "Hybrid nanoplasmonic-nanophotonic devices for on-chip biochemical sensing and spectroscopy." Diss., Georgia Institute of Technology, 2012. http://hdl.handle.net/1853/50145.
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Hybrid plasmonic-photonic structures were introduced as novel platforms for on-chip biochemical sensing and spectroscopy. By appropriate coupling of photonic and plasmonic modes, a hybrid architecture was realized that can benefit from the advantages of integrated photonics such as the low propagation loss, ultra-high Q modes, and robustness, as well as the advantages of nanoplasmonics such as extreme light localization, large sensitivities, and ultra-high field enhancements to bring about unique performance advantages for efficient on-chip sensing. These structures are highly sensitive and can effectively interact with the target biological and chemical molecules. It was shown that interrogation of single plasmonic nanoparticles is possible using a hybrid waveguide and microresonator-based structure, in which light is efficiently coupled from photonic structures to the integrated plasmonic structures. The design, implementation, and experimental demonstration of hybrid plasmonic-photonic structures for lab-on-chip biochemical sensing applications were discussed. The design goal was to achieve novel, robust, highly efficient, and high-throughput devices for on-chip sensing. The sensing scenarios of interest were label-free refractive index sensing and SERS. Nanofabrication processes were developed to realize the hybrid plasmonic-photonic structures. Silicon nitride was used as the material platform to realize the integrated photonic structure, and gold was used to realize plasmonic nanostructures. Special optical characterization setups were designed and implemented to test the performance of these nanoplasmonic and nanophotonic structures. The integration of the hybrid plasmonic-photonic structures with microfluidics was also optimized and demonstrated. The hybrid plasmonic-photonic-fluidic structures were used to detect different analytes at different concentrations. A complete course of research from design, fabrication, and characterization to demonstration of sensing applications was conducted to realize nanoplasmonic and integrated photonic structures. The novel structures developed in this research can open up new potentials for biochemical sensors with advanced on-chip functionalities and enhanced performances.
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Brown, M. D. "Light harvesting and photoconversion efficiency enhancement in dye-sensitized solar cells via molecular and photonic advancements." Thesis, University of Oxford, 2012. http://ora.ox.ac.uk/objects/uuid:651f8967-5d8b-42aa-bee1-04e0bbc04cea.
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The main goal of this thesis is to investigate and develop the physics of dye-based photovoltaic physics through molecular and photonic routes. Numerous photovoltaics devices have been fabricated through the course of this work to study their characteristics, performance, physical composition and action. The relative youth of the field of dye-based optoelectronics provides extensive scope for new research which provides fascinating opportunities in terms of physical processes.This thesis is divided into two main projects; exploring the adaption of conventional dye-sensitized solar cells via starkly different routes which serendipitously culminated in striking similarities at their conclusion. The first route is through incorporating spectrally complementary dye molecules with the intention of extending the range of light absorption of the final devices. This initial aim was achieved and was then furthered by the realisation of an unexpected and unprecedented energy transfer process occurring, imparting enhanced photocurrent generation in both the near-IR and visibile region. The second route involves investigating the effect on dye-sensitized solar cell physics and performance of the inclusion of metallic nanoparticles with the expectation of inducing plasmonic interactions. Novel systems were designed and implemented, devices were made which display significant performance enhancement, attributed to plasmonic coupling into the dyes and thereby increasing photocapture. A number of other investigations are documented whose current completion does not sufficiently warrant independent chapters but whose scientific interest is evident.
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Wheeler, Natalie. "Molecular and atomic confinement in large core photonic microcells for slow light and laser metrology applications." Thesis, University of Bath, 2010. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.538142.
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This thesis describes developments in the fabrication and applications of photonic microcells (PMCs). A PMC is a length of gas-filled hollow core-photonic crystal fibre (HC-PCF) that is hermetically sealed by splicing both ends to standard single mode fibre. A PMC enables integration of gas-filled HC-PCF into all-fibre systems with low insertion loss. PMCs have applications in coherent optics and metrology, where specific HC-PCF designs are advantageous. Two types of state-of-the-art HC-PCF, double bandgap HCPCF and large-pitch Kagome fibre, are fabricated. The double bandgap HC-PCF extends the usable bandwidth of the fibre by providing low loss guidance across two transmission bands. The large-pitch Kagome HC-PCF has a record low attenuation of 0.3 dB/m at 800 nm, while maintaining broadband guidance, which is partially attributed to the core shape. Three distinct developments in the field of PMCs are described. Firstly, a record length 20 metre acetylene-filled PMC is fabricated which is the key component in the first demonstration of an all-fibre slow and fast light system based on electromagnetically induced transparency. Secondly, a technique based on fibre tapering is presented which enables low loss integration of large core Kagome HC-PCFs into PMC form. Thirdly, micromirrors are developed and integrated with HC-PCF to confine light in the longitudinal dimension, providing a means to fabricate multi-pass PMCs. Two uncoated micromirrors are used to form a low finesse microcavity in Kagome HC-PCF, with record high fringe visibility using reflections from a silica/air junction. In collaboration with Kansas State University, an acetylene optical reference with sub-10 KHz accuracy and the first acetylene laser based on population inversion are demonstrated using Kagome HC-PCF.Finally, this thesis reports on rubidium vapour loading in HC-PCF with the ultimate aim being the production of a rubidium-filled PMC for applications in metrology. Preliminary results highlight the limited loading distance of the current technique and modified loading schemes are outlined accordingly.
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Mastrodonato, Cristiano Matteo. "Elaboration of fluorescent molecular probes and molecular-based nanoparticles for bioimaging purposes." Thesis, Bordeaux, 2017. http://www.theses.fr/2017BORD0652/document.
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Les techniques de fluorescence sont des outils de choix pour l’étude et la compréhension fine des processus biologiques. Ceci requiert toutefois l’utilisation de sondes fluorescentes parfaitement adaptées au but visé et répondant aux différentes exigences requises pour l’application visée. Dans ce cadre, nous nous sommes plus particulièrement intéressés à l’élaboration de sondes biphotoniques de pH adaptées à une mesure très sensible de faibles variations de pH autour du pH neutre. Les variations et gradients de pH sont en effet impliqués dans un certain nombre de processus biologiques importants et peuvent être associées à des dysfonctionnements liés à certaines maladies. Dans ce cadre, nous avons développé de nouvelles sondes fluorescentes de pH fluorescentes présentant à la fois un comportement ratiométrique, une forte sensibilité autour du pH neutre et facilement excitables dans le proche IR par absorption à deux photons. Ces sondes de structure quadrupolaire et bolamamphiphile permettent ainsi la détection ratiométrique du pH dans des environnements biologiques au moyen d'une excitation biphotonique dans le proche IR. En parallèle, nous nous sommes intéressés à l’élaboration de nanoparticules hyperbrillantes dédiées à l’imagerie biologique par microscopie de fluorescence induite par excitation à deux photons. Nous nous sommes plus particulièrement attachées au design de nanoparticules organiques fluorescentes constituées de molécules organiques de bas poids moléculaire (FONs). Cette approche offre en effet une grande flexibilité et la possibilité d’accéder à des nanosondes ayant des brillances comparables aux très populaires quantum dots mais moins toxiques et plus facilement dégradables. L’ingénierie moléculaire des fluorophores utilisés pour la préparation des FON est cruciale puisqu’elle influence fortement à la fois les propriétés photophysiques (brillance, couleur…) et leur propriétés physico-chimiques (stabilité chimique et structurale, stabilité colloïdale). Dans ce contexte, une librairie de nouveaux chromophores dipolaires a été synthétisée et utilisées pour la préparation de FON par la méthode de nano-précipitation. Leurs propriétés ont été étudiées afin de déterminer la relation entre la structure du chromophore et les propriétés globales des nanoparticules constituées de ces colorants. Ce travail a permis d’identifier les paramètres structuraux permettant d’accéder à des nanoparticules présentant à la fois une brillance exceptionnelle, une émission modulable du vert au rouge et proche IR et une remarquable stabilité colloïdale. Ces nanoparticules présentent des potentialités majeures pour l’imagerie in vivo par excitation et détection dans le proche IRFluorescence-based techniques are popular tools for the study and understanding of biological processes. This has prompted continuous research aimed at the development of a wide range of fluorescent probes specifically designed for specific applications. Among them, fluorescent pH probes are of much interest as pH variations or gradients are involved in many biological events and anomalous alterations are often related to the onset of dysfunctions and diseases. In this framework we have developed a series of promising two-photon pH fluorescent molecular probes. These quadrupolar bolaamphiphilic probes are of great interest, as they combine a steep pH dependence of their optical properties close to neutral pH, ratiometric behavior and large response to two-photon (2P) excitation in the NIR region. As such they offer much promise for ratiometric detection of the pH in biological environments and in situ monitoring of acidification. In parallel, we have been interest in the design of ultrabright nanoparticles for bioimaging purpose (in particular highly sensitive optical imaging). We chose to focus on Fluorescent Organic Nanoparticles made of organic molecules with low molecular weight (FONs) as they offer a flexible route and promising alternatives to toxic quantum dots. In this case the design of the dye used as building blocks of the FONs is of crucial importance and strongly influence the chemical and physical properties of the nanoparticles generated, such as their one and two-photon brightness and both their structural and colloidal stability. In that context a library of novel dipolar chromophores have been synthesized and used to prepare FONs using the nanoprecipitation method. Their properties were thoroughly investigated in order to determine the relationship between the molecular design of the isolated dye and the overall properties of the nanoparticles made of these dyes. As a result, Hyperbright FONs emitting in the green to NIR region and combining giant brightness and remarkable stability have been achieved. They offer major promise for bioimaging based on both excitation and detection in the NIR region
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Bernard, Alice. "Towards an electrically-injected optical parametric oscillator." Thesis, Sorbonne Paris Cité, 2018. http://www.theses.fr/2018USPCC104/document.
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Le travail présenté dans cette thèse porte sur la conception, la fabrication et la caractérisation de sources prévues pour fonctionner à la fois comme diode laser et comme oscillateur paramétrique optique. Ces lasers sont conçus pour émettre sur un mode d’ordre supérieur afin de permettre une conversion de fréquence paramétrique avec les modes fondamentaux du guide à la fréquence moitié. La diode laser et l’OPO partagent la même cavité optique ; pour assurer l’accord de phase et corriger les écarts à la structure nominale induits lors de l’élaboration par épitaxie, la largeur de ruban est utilisée comme paramètre de contrôle des indices efficaces. Les diodes proposées sont donc étroites (3-5 µm) et gravées profondément. En conséquence, il est potentiellement intéressant d’utiliser des boîtes quantiques pour limiter les recombinaisons non radiatives sur les flancs. Dans le cadre de ce travail, nous avons conçu des diodes basées sur ce principe pour les deux systèmes GaAs/AlGaAs et InGaAsP/InP, qui permettent respectivement d’obtenir potentiellement une émission OPO au voisinage de 2 µm ou de 3 µm. Dans le cas de l’InGaAsP/InP, nous avons étudié au préalable l’indice de réfraction des alliages InGaAsP dans une plage de longueur d’onde jusque-là non couverte par la littérature. Ces données ont été acquises via des mesures d’indice efficace (m-lines) de couches guidantes d’InGaAsP épitaxiées en accord de maille sur un substrat d’InP. Pour des structures laser-OPO optimisées, les simulations montrent que le seuil OPO devrait être obtenu pour une puissance de pompe intracavité de quelques centaines de mW, qu’il est réaliste d’atteindre pour des diodes laser à l’état de l’art. Nous avons étudié les propriétés électro-optiques de diodes lasers à puits quantiques GaAs/AlGaAs réalisées sur la base de nos dessins; l’observation de l’effet laser sur le mode TE2 valide le dessin vertical original de nos diodes lasers. En vue de la fabrication de laser-OPO à ruban étroit, nous avons développé des procédés de fabrication nouveaux sur la Plateforme Technologique Amont (CEA – Grenoble), notamment la gravure profonde (>10 µm) par ICP-RIE. Enfin, nous avons proposé un concept alternatif de diode-OPO, comprenant des cavités laser et OPO distinctes couplées par un taper adiabatiqueThe work presented in this thesis deals with the design, fabrication and characterization of sources intended to function as both laser diodes and optical parametric oscillators. These lasers are designed to emit on a higher order mode to allow parametric frequency conversion with fundamental modes of the guide at half frequency. The laser diode and OPO share the same optical cavity; to ensure phase matching and correct nominal structure deviations induced during epitaxial processing, the ridge width is used as a control parameter of the effective indices. The proposed diodes are therefore narrow (3-5 μm) and etched deeply. Consequently, it is potentially interesting to use quantum dots to limit non-radiative recombination on the sidewalls. In the context of this work, we have designed diodes based on this principle for the two GaAs/AlGaAs and InGaAsP/InP systems, which respectively allow to potentially obtain an OPO emission in the vicinity of 2 μm or 3 μm. In the case of InGaAsP/InP, we previously studied the refractive index of InGaAsP alloys in a wavelength range not covered by literature to this day. This data was acquired via effective m-line index measurements of InGaAsP guiding layers epitaxially grown on and lattice-matched to an InP substrate. For optimized laser-OPO structures, simulations show that the OPO threshold should be obtained for an intracavity pump power of a few hundred mW, which is realistic to achieve for state-of-the-art laser diodes. We have studied the electro-optical properties of GaAs/AlGaAs quantum well laser diodes made on the basis of our designs; the observation of the laser effect on the TE2 mode validates the original vertical design of our laser diodes. For the manufacture of narrow-ridge lasers-OPOs, we have developed new manufacturing processes on the Plateforme Technologique Amont (Upstream Technology Platform, CEA - Grenoble), including deep etching (> 10 μm) by ICP-RIE. Finally, we have proposed an alternative diode-OPO concept, comprising distinct laser and OPO cavities coupled by an adiabatic taper
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Ngo, Ndimba Alphonsine L. "Photoactive molecular assemblies for optical limiting and bio-imaging." Thesis, Rennes 1, 2020. http://www.theses.fr/2020REN1S103.
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Dans cette thèse, nous ciblons de nouveaux absorbeurs biphotoniques pour la bio-imagerie et la limitation optique. Nous nous sommes intéressés plus précisément à des octupôles, structures connues pour posséder des propriétés intéressantes en optique non-linéaire et plus particulièrement en absorption à deux photons. Ainsi, les cœurs isocyanurate et 1,3,5-triazine, connus comme étant des accepteurs, mènent à des octupôles bidimensionnels lorsqu’ils sont substitués de façon symétrique. Pour lors, les isocyanurates ont été peu étudiés pour l’optique non linéaire tandis que les triazines ont déjà été étudiées dans ce cadre et sont connues pour avoir de bonnes propriétés en absorption à deux photons. Dans un premier temps, nous nous sommes intéressés à la synthèse d’isocyanurates organiques et à l’étude de leurs propriétés optiques. Nous avons plus particulièrement étudié l’effet de la planarisation et de l’extension du système conjugué. Dans un deuxième temps, nous nous sommes intéressés à la synthèse et à l’étude des propriétés optiques des tristyryltriazines afin de comparer celles-ci à leurs analogues tristyrylisocyanurates et d’étudier l’influence du cœur sur les propriétés en sachant que la triazine est un cœur plus électroattracteur que l’isocyanurate. Puis, nous nous sommes intéressés à la synthèse de complexes ruthénium-alkynyl trinucléaires à cœurs isocyanurates et triazines, car le ruthénium est un métal d6 connu pour améliorer les propriétés en optique non linéaire. Enfin, nous avons synthétisé des dérivés hydrosolubles de composés organiques qui présentaient les propriétés optiques les plus prometteuses pour la bio-imagerie. En collaboration avec le Dr. Gary-Bobo, nous avons pu confirmer le potentiel de ces molécules pour de telles applicationsIn this work, new biphotonic absorbers were targeted for applications in bio-imaging and optical limiting. We have investigated the synthesis of octupoles since these multipolar structures were often shown to lead to interesting optical properties, especially two-photon absorption. The structures studied were isocyanurate- or 1,3,5-triazine-cored star-shaped derivatives. Both cores are known to be electron-accepting units and to give rise to two-dimensional octupoles when symmetrically substituted. So far, isocyanurates have not often been studied in nonlinear optics, whereas triazines have already been screened and were shown to have good two-photon absorption properties. We first focused on the synthesis of organic isocyanurates and on the study of their optical properties. We started by studying the planarization effect of the extension of the peripheral arms on the optical properties. We then focused on the synthesis and study tristyryltriazines analogous to the previous tristyrylisocyanurates. New structure/property relationships were thus established since the triazine is more electron-attracting than the isocyanurate core. We next synthesized ruthenium-alkynyl trinuclear complexes with isocyanurate and triazine cores, since ruthenium is a d6 metal known to enhance the nonlinear optical properties. We finally studied water-soluble derivatives for bio-imaging. In collaboration with Dr. Gary-Bobo we confirmed their potential for such applications
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Gurke, Johannes. "Protons and Photons." Doctoral thesis, Humboldt-Universität zu Berlin, 2019. http://dx.doi.org/10.18452/19747.
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Gegenstand dieser Arbeit ist die Frage wie thermische und photochemische Gleichgewichte verbunden werden können und sich gegenseitig beeinflussen. Dazu wurden zwei Projekte bearbeitet, zum einen das Konzept der „säure-katalysierten Zykloreversion“ und zum anderen das Konzept der „licht-induzierten pKs Veränderung“. Im ersten Konzepte wurde eine extern steuerbare, thermische Rückreaktion genutzt, um die Zusammensetzung im photostationären Zustand zu kontrollieren. Durch Zugabe von katalytischen Mengen einer starken Säure wurde die Ringöffnung eines Diarylethens, welches mit einem Flurenol substituiert ist, eingeleitet. Der zugrundeliegende Prozess wurde kinetisch und thermodynamisch, sowohl durch Experimente als auch durch computergestützte Rechnungen beschrieben. Eine säure-induzierte Dehydratation öffnet einen neuen Reaktionspfad, wodurch die normalerweise sehr hohe Reaktionsbarriere der Ringöffnung umgangen werden kann. Die quantitative Umsetzung mit Säure führt zu einer kompletten Löschung der photochemischen Reaktivität. Dieses Konzept kann in der Speicherung von Lichtenergie in photochromen metastabilen Systemen genutzt werden. Durch die Nutzung von 3-H-Thiazol-2-on als Rest im Diarylethen konnte eine signifikante pKs Änderung von 2.8 Einheiten in wässriger Umgebung erreicht werden. Dabei wurden zwei Säure-Base Gleichgewichtssysteme miteinander gekoppelt, welche an der thermischen Umwandlung gehindert sind, jedoch photochemisch ineinander überführt werden können. Des Weiteren wurde eine hohe Abhängigkeit der Quantenausbeute von dem Protonierung festgestellt. Diese wurde genutzt um die Performance der Photoreaktion zu beeinflussen. Die Beeinflussung der Photoreaktion erfolgt nicht durch Veränderung der Energetik des Grundzustandes, sondern durch Veränderung der Potentialhyperfläche des angeregten Zustandes. Durch neue molekulare Designs konnte eine signifikante Verbesserung im Vergleich zu bekannter Molekülen und Konzepten in beiden Projekten erreicht werden.Two projects are implemented in this work, which share the goal to interconnect acid-base equilibria with the photoreactions of diarylethene (DAE) photoswitches. This task can be divided into two logic questions: How can photochemical equilibria be controlled or rather influenced via an acidic or basic stimulus and how can a photoreaction induce control over an acid-base equilibrium? In the first project, “Acid-Catalyzed Cycloreversion”, an externally tunable thermal back reaction was designed to influence a photochemical equilibrium. Upon addition of catalytic amounts of acid, a closed DAE carrying a fluorenol moiety undergoes facile thermal ring opening. The underlying thermodynamics and kinetics of the entire system have been analyzed experimentally as well as computationally. Appling an excess of acid leads to a complete inhibition of the photoreaction through the introduction of a charge-transfer. My work suggests that acid catalysis provides a useful tool to bypass thermal barriers, potentially usable to efficiently trigger the release of light energy stored in photoswitches. In the second project, entitled “Light-induced pKa Modulation”, a significant pKa change of 2.8 units in an aqueous medium was achieved by connecting two different acid-base equilibria. These thermodynamic equilibria are separated by a high activation barrier, overcome by a photoreaction. The developed system which is based on the incorporation of a 3 H thiazol 2 one moiety into a DAE, shows a strong dependency of the quantum yield and hence, of the photoconversion on the protonation state. Adjusting the pH within the range of the pKa change, a substantial enhancement of the photoconversion is achievable as well as a distinct alteration of the performance of the photoreaction. This effect does not originate from different reaction paths on the ground state potential energy surface (PES), but results presumably from a protonated state dependent difference in the excited PES.
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Jackson, Gavin John. "Local adsorption structure determination of chemically-specific species using normal incidence X-ray standing wavefields." Thesis, University of Warwick, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.343835.
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Le, Liepvre Sylvain. "Supramolecular self-assemblies for plasmonics : a bottom-up approach to efficient photonic nanodevices." Thesis, Université Paris-Saclay (ComUE), 2017. http://www.theses.fr/2017SACLS330/document.
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Dans cette thèse, nous avons étudié les propriétés photoniques et vibrationnelles de monocouches moléculaires auto-assemblées sur graphène et la possibilité d'utiliser des multicouches auto-assemblées de pérylène comme milieu à gain pour l'amplification de plasmons. Le graphène, en tant que matériau transparent et conducteur, a permis pour la première fois de corréler la géométrie du réseau de l’auto-assemblage supramoléculaire avec ses propriétés optiques, grâce à la microscopie à effet tunnel et à des mesures de spectroscopiques optiques et Raman. En comparant plusieurs colorants autoassemblés sur le graphène, nous avons mis en lumière les effets des interactions intermoléculaires et des interactions colorant-graphène sur le spectre d'absorption du colorant adsorbé. Le transfert d'énergie rapide des colorants vers la couche degraphène par les mécanismes de Förster et de Dexter empêche toute relaxation radiative du colorant..Néanmoins, nous avons démontré la première fonctionnalisation fluorescente non-covalente du graphène par une monocouche de colorants autoassemblée en mettant en place une stratégie à base d’espaceurs. Nous avons exploité l’extinction rapide de la fluorescence des colorants par le graphène pour étudier les spectres Raman des auto-assemblages moléculaires sur graphène, et nous avons révélé l'apparition d'un mode vibrationnel couplé entre les molécules adsorbées et le substrat de graphène. Nous avons démontré le régime de couplage fort entre un auto-assemblage tri-dimensionnel de pérylène et un plasmon polariton de surface en optimisant l'orientation et l'organisation des molécules de colorant par rapport au champ électrique du mode de plasmon. Nous avons prouvé que les milieux de gain auto-assemblés en agrégats-J peuvent théoriquement conduire à des milieux de gain efficaces pour l'amplification de plasmons. Cependant, nous avons révélé expérimentalement que les recombinaisons exciton-exciton limitent le taux de pompage à des fluences élevées dans ces milieux densesIn this work, we have studied thephotonic and vibrational properties of selfassembled molecular monolayers on graphene and the possibility to use perylene self-assembled multilayers as a gain medium for plasmon amplification. Graphene, as a transparent and conductive material, has offered for the first time to correlate the self-assembly structure as deduced from scanning tunneling microscopy to photonic properties as analyzed by optical and Raman spectroscopy measurements. By comparing several self-assembled dyes on graphene we have shed lighton how intermolecular and dye-graphene interactions modify the absorption spectrum of the adsorbed dye.Fast Förster and Dexter energy transfer from the adsorbed dyes to the graphene layer prevent any radiative decay of the dye.Nevertheless, we have demonstrated the first fluorescent non-covalent functionalization of graphene by a supramolecular self-assembled monolayer using a spacer approach.We have exploited the fast dye fluorescence quenching by graphene to study Raman spectra of self-assembled dye on graphene, and we have shown the appearance of a coupled vibrational mode between the adsorbed molecules and the graphene substrate. We have demonstrated the strong couplingregime between a three-dimensional perylene self-assembly and a propagating plasmon polariton by optimizing the orientation and the organisation of the dye molecules compared to the electric field of the plasmon mode. We have shown that J-aggregated self-assembled gain media may theoretically lead to efficient gain media for plasmon amplification. However, we experimentally demonstrated that exciton-exciton recombination limits the achievable pumping rate at high fluences in such dense media
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Leung, Calvin. "Quantum Foundations with Astronomical Photons." Scholarship @ Claremont, 2017. http://scholarship.claremont.edu/hmc_theses/98.
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Theoretical work in quantum information has demonstrated that a classical hidden-variable model of an entangled singlet state can explain nonclassical correlations observed in tests of Bell’s inequality if while measuring the Bell correlation, the underlying probability distribution of the hidden-variable changes depending on the measurement basis. To rule out this possibility, distant quasars can be utilized as random number generators to set measurement bases in an experimental test of Bell’s inequality. Here we report on the design and characterization of a device that uses the color of incoming quasar photons to output a random bit with nanosecond latency. Through the 1-meter telescope at JPL Table Mountain Observatory, we observe and generate random bits from quasars with redshifts z = 0.1−3.9. In addition, we formulate a mathematical model that quantifies the fidelity of the bits generated.
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Rezai, Mohammad [Verfasser]. "Quantum Information Processing with Photons from a Single Molecule / Mohammad Rezai." München : Verlag Dr. Hut, 2018. http://d-nb.info/1172582009/34.
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Kohler, Felix [Verfasser], and Alexander [Akademischer Betreuer] Rohrbach. "Photonic force based investigations of filopodial dynamics and coupled molecular motors = Photonische Kraft basierte Untersuchungen zur Filopodiendynamik und gekoppelte molekulare Motoren." Freiburg : Universität, 2013. http://d-nb.info/1123477345/34.
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SÌmiaÅ‚ek, MaÅ‚gorzata. "Damage to DNA induced by low energy electrons and photons : mechanisms and analysis at the molecular level." Thesis, Open University, 2007. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.446286.
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Knabe, Kevin. "Using saturated absorption spectroscopy on acetylene-filled hollow-core fibers for absolute frequency measurements." Diss., Manhattan, Kan. : Kansas State University, 2010. http://hdl.handle.net/2097/4126.
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