Global ETD Search
Search theses and dissertations gathered from participating repositories worldwide. Every result links back to the library that holds it. No account is needed.
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Showing 1 to 20 of 57 for “"frequency conversion"”.
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Nonreciprocal microwave devices using parametric frequency conversion
… microwave devices enabled by parametric frequency conversion. Although such devices have been explored somewhat superficially in the 1960s, resurgent interest in low-noise nonreciprocal components has motivated new research in parametric frequency conversion. In particular, this work …
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Characterisation of a dual frequency conversion superheterodyne receiver
This dissertation starts off with a brief introduction of the SKA project, and explain how it relates to the KAT project. Then certain receiver design techniques and parameters will be discussed together with receiver design trade-offs will be presented. This dissertation will then focus on the …
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Nonlinear optical frequency conversion of mode-locked all-solid-state lasers
… lasers as a platform for nonlinear optical frequency conversion experiments. One objective is to create an ultrashort-pulsed source that is tunable between λ= 600nm and λ= 700nm, since currently no other laser gain media exists that covers this region of the electromagnetic spectrum. This …
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Powers scaling and nonlinear frequency conversion of single-frequency lasers based
… µm line whilst retaining, efficient, single-frequency, diffraction limited output, the characteristics of low power operation. This strategy reduces the effects of energy transfer up-conversion (ETU), which can decrease the lifetime of the upper lasing level and increase the heat generated …
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Frequency conversion in nonlinear optical waveguides : from classical to quantum applications
… It combines the phenomena of nonlinearoptical frequency conversion with waveguiding and coupling, taking advantage of new opportunities presented by advances in fabrication technologies of micro- and nano-waveguides. In this dissertation an in-depth analysis of quantum and classical properties …
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Frequency conversion in nonlinear optical waveguides : from classical to quantum applications
… It combines the phenomena of nonlinearoptical frequency conversion with waveguiding and coupling, taking advantage of new opportunities presented by advances in fabrication technologies of micro- and nano-waveguides. In this dissertation an in-depth analysis of quantum and classical properties …
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Low Loss Orientation-Patterned Gallium Arsenide (OPGaAs) Waveguides for Nonlinear Infrared Frequency Conversion
The mid-IR frequency band (λ = 2-5 µm) contains several atmospheric transmission windows making it a region of interest for a variety of medical, scientific, commercial, and military applications. Recently there has been a growing interest in using orientation-patterned semiconductors such as …
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Techniques in frequency conversion and time-resolved spectroscopy with nonlinear optical processes in the femtosecond regime
Nichtlineare Frequenzumsetzung der niederenergetischen femtosekunden Laserpulsen wurde in den Festkörpermitteln nachgeforscht. Ramanumwandlung im weiss-Licht-freien Regime des impulsiven stimulierten Raman Streuungs wurde erzielt, indem man KGW-Kristall mit den Bessel-Lichtstrahl pumpte. …
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Tailoring the emission of stripe-array diode lasers with external cavities to enable nonlinear frequency conversion
… from diode lasers is available, yet. Nonlinear frequency conversion of near-infrared radiation is a common way to generate coherent emission in the visible spectral range. However, radiation with extraordinary spatial temporal and spectral quality is required to pump frequency conversion. Broad …
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Geometric manipulation of light : from nonlinear optics to invisibility cloaks
… by macroscopic Maxwell's equations. One is frequency conversion of such waves using small intrinsic material nonlinearities. We study conversion of an input signal at frequency w1 to frequency Wk due to second or third harmonic generation or four-wave mixing using coupled-mode theory. Using …
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Frequency down-conversion for quantum networking with nitrogen-vacancy centers in diamond
Quantum frequency conversion (QFC) devices are critical to building long-distance quantum networks, which would connect quantum memories located at distant nodes through optical channels for efficient entanglement distribution. The nitrogen-vacancy (NV) center in diamond is an attractive candidate …
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Tunable, continuous-wave semiconductor disk lasers with emission in the deep ultraviolet
… first demonstration of a deep ultraviolet, frequency tripled semiconductor disk laser (SDL). The construction of such a laser is described, together with a review of the relevant theory and investigation of the underlying processes in order to improve the system.;SDLs based on gallium indium …
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Power Scaling of Laser Oscillators and Amplifiers Based on Nd:YVO<sub>4</sub>
… of these laser sources as pump sources for frequency conversion in optical parametric devices.<br/>
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Control of Optical Processes in Diamond using Plasmonic Nanogap Cavities
… orders of magnitude of enhancement of nonlinear frequency conversion was also observed in diamond thin films coupled to these metasurfaces. Furthermore, a robust mechanism for actively tuning the nanocavity absorption resonance by integrating sub-10-nm films of the phase-change material vanadium …
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Nonlinear and Time-Modulated Metamaterials: Applications at Microwave Frequencies
… including the creation of nonreciprocal devices, frequency conversion, and more. In this dissertation, we explore, investigate, design, and fabricate metamaterials that open new applications for nonlinearity-based and time-varying devices, particularly in the context of enabling potential …
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Harmonic and Supercontinuum Generation in Zinc-Blende Materials
… in spectroscopy and strong field studies. Frequency conversion in nonlinear optical crystals is one of the promising techniques for generating the spectral coverage over one octave in the MIR. In polycrystalline structured semiconductors, relaxed phase matching conditions greatly extend the …
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Fluctuation-induced interactions and nonlinear nanophotonics
… for studying Casimir forces and nonlinear frequency conversion in nanophotonic media consisting of arbitrary geometries and materials. The first section of the thesis focuses on the study of various geometry-enabled resonant effects leading to strong nonlinear interactions. The starting …
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Engineered Plasmonic Nanostructures for Infrared Spectroscopy, Refractive Index Sensing and Nonlinear Optics
… studied the dependence of plasmon resonance frequency on the size, shape and dielectric environment of the nanoscale system, mainly for sensing applications. The intense and localized field, generated by two adjacent metallic nanostructures when appropriately illuminated, has been utilized …
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Novel semiconductor based broadly tunable light sources
… technologies, in particular nonlinear frequency conversion and parametric sources, have led to the realisation of a new generation of laser sources. Furthermore, the advent of a new generation of quasi-phase-matched, waveguided and semiconductor nonlinear materials together with novel …
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Efficient and coherent frequency conversions and nonlinear interference in optical parametric and atomic Raman processes
<p>By implementing a parametric down-conversion process with a strong signal field injection, we demonstrate that frequency down-conversion from pump photons to idler photons can be a coherent process. Contrary to a common misconception, we show that the process can be free of quantum noise. With …
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