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1
Clark, Philip James. "The BaBar light pulser system." Thesis, University of Edinburgh, 2000. http://hdl.handle.net/1842/13419.
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The BABAR experiment at the PEP-II e+e- collider at SLAC in California started taking data in May 1999. The aim of the experiment is to study CP violation in the B meson system. A central part of the BABAR detector is CsI(TI) electromagnetic calorimeter. To make precision measurements with a calorimeter in a high luminosity environment requires that the crystals are well calibrated and continually monitored for radiation damage. However, this should not impact the total integrated luminosity. To achieve this goal a fibre-optic light pulser system was designed. The light sources chosen were Xenon flash lamps. A novel light distribution method was developed using an array of graded index microlenses. Initial results from performance studies are presented.
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Kocian, Martin Lukas. "Das Lichtpulsersystem des elektromagnetischen CsI(Tl)-Kalorimeters des Babar-Detektors." Doctoral thesis, Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2000. http://nbn-resolving.de/urn:nbn:de:swb:14-994685405218-39354.
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A light pulser system for the Babar CsI(Tl) calorimeter, capable of monitoring the light yield of the 6580 crystals and of checking the function and linearity of the readout electronics, was developed in a collaboration with groups from Bochum and Edinburgh. The light pulser system is based on the coupling of light from Xenon flashlamps through optical fibers into the individual crystals. The absolute intensity is measured by two special reference systems whose stability is monitored using a radioactive source. During the construction phase the light pulser was used to check the electronics in order to ensure its functioning before the insertion of the calorimeter into the detector where the preamplifier electronics is inaccessable for repair. In monitoring the short term performance of the light pulser system, the stability over one week is better than 0.15 %. Over six months between February and August 2000 the crystal response, as measured by the light pulser, of the three rings of the endcap that are closest to the beam dropped by up to 2 % in comparison with the three outer rings of the endcap, due to radiation damage. Through linearity measurements with the light pulser a flaw in the ADC boards of the calorimeter electronics, which will be fixed in the near future, and cross-talk between channels was found. By a software correction of these effects implemented by members of the collaboration an improvement of the energy resolution of the calorimeter was achievedFuer das CsI(Tl)-Kalorimeter des Babar-Detektors wurde in Zusammenarbeit mit Gruppen aus Bochum und Edinburgh ein Lichtpulsersystem entwickelt, das in der Lage ist, die Lichtausbeute der 6580 Kristalle zu monitorieren und die Funktionsfaehigkeit und Linearitaet der Kalorimeterelektronik zu ueberpruefen. Das Lichtpulsersystem basiert auf der Einkopplung des Lichts von Xenon-Blitzlampen ueber Lichtleitfasern in einzelne Kristalle. Die absolute Lichtmenge wird durch zwei spezielle Lichtnormale gemessen, deren Stabilitaet durch eine radioaktive Quelle monitoriert wird. In der Aufbauphase kam der Lichtpulser fuer die Ueberpruefung der Elektronik zum Einsatz, um deren Funktionsfaehigkeit sicherzustellen, bevor das Kalorimeter in den Detektor eingebaut wurde, weil danach die Vorverstaerkerelektronik fuer Reparaturen nicht mehr zugaenglich war. In der Monitorierung ist die Kurzzeitstabilitaet des Lichtpulsersystems ueber eine Woche besser als 0,15 %. Ueber sechs Monate zwischen Februar und August 2000 sank, bedingt durch Strahlenschaeden, die mit dem Lichtpulser gemessene Antwort der Kristalle fuer die strahlnaechsten drei Ringe der Endkappe um bis zu 2 % staerker als in den aeusseren drei Ringen der Endkappe. Durch die Linearitaetsmessungen mit dem Lichtpulser konnte ein Fehler in der Kalorimeterelektronik im Bereich der ADC-Karten, der in naher Zukunft behoben werden wird, sowie ein Uebersprechen zwischen den Kanaelen gefunden werden. Durch Softwarekorrekturen dieser Effekte von seiten der Kollaboration konnte eine Verbesserung der Energieaufloesung des Kalorimeters erreicht werden
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Bolatbek, Zhanibek. "Detection and Pulse Shaping of Continuous Wave and Pulsed Broadband Light." University of Dayton / OhioLINK, 2021. http://rave.ohiolink.edu/etdc/view?acc_num=dayton1619634310138999.
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Biaggio, Ivan Biaggio Ivan Biaggio Ivan Biaggio Ivan. "Photorefractive effects induced by short light pulses /." [S.l.] : [s.n.], 1993. http://e-collection.ethbib.ethz.ch/show?type=diss&nr=10009.
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Wang, Tao. "Waterborne microorganism disinfection with pulsed UV light." Thesis, University of Strathclyde, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.417348.
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范詩雲 and Sewan Fan. "Investigation of pulse light emission from sonoluminescence." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 1998. http://hub.hku.hk/bib/B31236832.
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Fan, Sewan. "Investigation of pulse light emission from sonoluminescence /." Hong Kong : University of Hong Kong, 1998. http://sunzi.lib.hku.hk/hkuto/record.jsp?B19737038.
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Goulielmakis, Eleftherios. "Complete Characterization of Light Waves using Attosecond Pulses." Diss., lmu, 2005. http://nbn-resolving.de/urn:nbn:de:bvb:19-41112.
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Daly, Elizabeth Marion. "Generation, measurement, and application of pulsed squeezed light." Thesis, University of Strathclyde, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.367066.
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Mang, Matthias M. "Interferometric spatio-temporal characterisation of ultrashort light pulses." Thesis, University of Oxford, 2014. http://ora.ox.ac.uk/objects/uuid:163c5374-1466-4c4d-a0f5-c4e66b27e2ac.
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The main topic of this thesis is the development of novel diagnostics for the characterisation of infrared femtosecond and extreme-ultraviolet (XUV) attosecond pulses. High-resolution interferometric methods are applied to high harmonic radiation, both to measure the properties of the XUV light and to relate this information to the physics of the fundamental generation process. To do so, a complete high harmonic beamline has been built and optimised to enable the observation of strong signatures of the macroscopic response of the medium. The distinct spatial characteristics of long and short trajectories are studied, as well as the interference between them. An interferometric measurement allows the extraction of the atomic dipole phase, which gives direct access to the sub-cycle electron dynamics. A major focus of this thesis is on the development of a novel method which simultaneously characterises two independent electric fields as a function of any degree of freedom in which it is possible to shear one of the beams. Since each field alternately takes the role of the reference to retrieve the other field, this technique is referred to as mutual interferometric characterisation of electric-fields (MICE). One of the key features of MICE is that no sheared but otherwise identical replica of the test pulse needs to be generated, which is a typical requirement of self-referencing techniques. Furthermore, no a priori information is needed for the reconstruction. The strength and the wide applicability of MICE are demonstrated using two fundamentally different examples. First, the temporal pulse profiles of two infrared femtosecond pulses are simultaneously reconstructed in a single laser shot. In the second demonstration, the MICE approach is used to simultaneously reconstruct the wavefronts of two high harmonic beams. Having this new technique at hand, the phase properties of the different quantum trajectories are compared. All pulse characterisation techniques implicitly assume full coherence of the beam. This, however, is often not the case in practice, in particular when dealing with complex XUV light sources. Here the standard characterisation techniques fail to provide an accurate description of the electric field. Instead, the electric field must be seen as a statistical mixture of different contributions to the overall field. Here an interferometric experiment is first proposed and then performed involving multiple lateral shears to measure the two-point correlation function of high harmonic radiation. This directly provides information about the existence and the magnitude of partial coherence of high harmonics.
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Rahimiangolkhandani, Mitra. "Interaction of Structured Femtosecond Light Pulses with Matter." Thesis, Université d'Ottawa / University of Ottawa, 2021. http://hdl.handle.net/10393/42334.
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Physics and potential applications of femtosecond laser pulses interacting with matter have captured interest in various fields, such as nonlinear optics, laser micromachining, integrated optics, and solar cell technologies. On the one hand, such ultrashort intense pulses make them practical elegant tools to be utilized for direct structuring of materials with high accuracy and numerous potential applications. On the other hand, studying the fundamental aspects and nonlinear nature of such interactions opens new remarkable venues for various unique investigations. In recent years, the emerging topic of structured light (also known as twisted or optical vortex light), i.e., a beam of light with a twisted wave-front that can carry orbital angular momentum (OAM), has attracted the attention of many researchers working in the field of light-matter interaction. Such beams offer various applications from classical and quantum communication to imaging, micro/nano-manipulation, and modification of fundamental processes involved in light-matter interactions, e.g., absorption and emission. Nevertheless, the fabrication of complex structures, controlled modification, and achieving a high spatial resolution in material processing still remain in the spotlight. Moreover, the fundamental role of orbital angular momentum in the nonlinear absorption of materials, particularly in solids, has yet remained a subject of debate. Addressing these points was the main motive behind this dissertation. To accomplish this objective and investigate new aspects of structured light-matter interaction, I conducted various experiments, the results of which are presented in this work. The general idea was to study the interaction of femtosecond laser radiation, having a structured phase and polarization, with the matter in two aspects: (i) surface morphology modification and (ii) nonlinear absorption of solids. In this regard, I studied surface processing of crystalline silicon and CVD diamond with femtosecond laser vortex pulses generated by a birefringent phase-plate, known as q-plate, in single and multiple pulse irradiation regimes, respectively. The characterization of the modified region was performed using optical microscopy, scanning electron microscopy (SEM), and atomic force microscopy (AFM). I demonstrated that upon irradiation of a single vortex pulse on silicon, a nano-cone structure is formed within the ablated crater, whose height was independent of the helicity of the twisted light. However, for a linearly polarized vortex pulse, the height of the nano-cone decreases at higher pulse energies. The dynamics of nano-cone formation and the role of polarization were also investigated by simulating the mass transport function in this process. Moreover, using superimposed vortex beams, we fabricated complex patterns containing several nano-cones, by single-shot irradiation on the silicon surface. My experimental results offer an ability to actively control and manipulate material, in terms of the nanocones position, in two dimensions with an ultra-high resolution. I further proceeded with our experiments in the multiple pulse regime on a diamond target. By irradiation of a high number of superimposed vortex pulses, I was able to imprint complex polarization states of structured light on the target surface in the form of periodic nano-ripples. This procedure enabled us to not only generate spatially varying nano-gratings but also directly visualize and study very complex states of polarization. Besides these surface structuring, I carried out experimental studies to investigate the response of bulk material to an incident circularly polarized vortex beam that carries orbital angular momentum. The experimental results reveal, for the first time, that such an interaction can produce a differential absorption that gives rise to helical dichroism. We demonstrate that this response is sensitive to the handedness and degree of the twist in the incident vortex beam. Such a dichroism effect may be attributed to the excitation of dipole-forbidden atomic transitions, e.g., electric quadrupole transitions. However, this explanation is not absolute and remains open to further research and investigations.
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Heffer, J. S. "Towards precision gravimetry using light-pulse atom interferometry." Thesis, University of Liverpool, 2017. http://livrepository.liverpool.ac.uk/3014202/.
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A light-pulse atom interferometer for inertial sensing applications such as gravimetry is being commissioned, where the prototype has a target relative precision (σ g /g) of one part per million to enable geophysics applications, which is three orders of magnitude less sensitive than commercial optical gravimeters, but with the potential to exceed these. As part of this, a rubidium-85 magneto-optical trap was upgraded using optical amplification and fibre optics to capture an atom population number of O(10 8 ) and sub-Doppler cooling techniques have been used to reach ultracold temperatures of 20 μK. Several interferometer subsystems have been developed, including extensive optical systems featuring a high-specification optical modulator and laser-induced fluorescence detection. Preliminary investigations into the coherent manipulation of atomic states have been implemented and the resonance peak of a stimulated Raman transition has been observed.
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Holzwarth, Ronald. "Measuring the Frequency of Light using Femtosecond Laser Pulses." Diss., lmu, 2001. http://nbn-resolving.de/urn:nbn:de:bvb:19-3214.
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Holzwarth, Ronald. "Measuring the frequency of light using femtosecond laser pulses." [S.l.] : [s.n.], 2000. http://deposit.ddb.de/cgi-bin/dokserv?idn=96303006X.
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Bergman, Keren. "Quantum noise reduction with pulsed light in optical fibers." Thesis, Massachusetts Institute of Technology, 1994. http://hdl.handle.net/1721.1/37718.
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Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 1994.Includes bibliographical references (leaves 137-144).
by Keren Bergman.
Ph.D.
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Pinner, Dickon John. "Pulsed electrical excitation of conjugated polymer light-emitting diodes." Thesis, University of Cambridge, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.620940.
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Kotru, Krish. "Timekeeping and accelerometry with robust light pulse atom interferometers." Thesis, Massachusetts Institute of Technology, 2015. http://hdl.handle.net/1721.1/98681.
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Thesis: Ph. D., Massachusetts Institute of Technology, Department of Aeronautics and Astronautics, 2015.Cataloged from PDF version of thesis.
Includes bibliographical references (pages 165-173).
Light pulse atom interferometry (LPAI) is a powerful technique for precision measurements of inertial forces and time. Laboratory LPAI systems currently achieve state-ofthe- art acceleration sensitivity and establish the international atomic time standard. However, the realization of practical LPAI in dynamic environments (e.g., rapidly accelerating or rotating platforms) has been limited in part by atom optics-the analogues to optical beamsplitters and mirrors. Atom optics in traditional LPAIs are composed of resonant laser pulses that are susceptible to variations in optical detuning and intensity expected in sensors designed for dynamic environments. This thesis investigates atom optics that use frequency- and intensity-modulated laser pulses to suppress sensitivity to these inhomogeneities. For atomic timekeeping applications, a Ramsey LPAI sequence based on stimulated Raman transitions and frequency-swept adiabatic rapid passage (ARP) was developed. Raman ARP drives coherent transfer in an effective two-level atomic system by sweeping the Raman detuning through the two-photon resonance. In experiments with ¹³³Cs atoms, Raman ARP reduced the sensitivity of Ramsey sequences to differential AC Stark shifts by about two orders of magnitude, relative to standard Raman transitions. Raman ARP also preserved fringe contrast despite substantial intensity inhomogeneity. The fractional frequency uncertainty of the ARP Ramsey sequence was limited by second-order Zeeman shifts to ~3.5 x 10-¹² after about 2500 s of averaging. For accelerometry applications, Raman ARP provided efficient, large momentum transfer (LMT) atom optics in an acceleration-sensitive LPAI. These atom optics produced momentum splittings of up to 30 photon recoil momenta between interfering wavepackets-the largest to date for Raman atom optics. This splitting, in principle, enables up to a factor-of-15 improvement in sensitivity over the nominal interferometer. By forgoing cooling methods that reduce atom number, this LMT method reduces the measurement uncertainty due to atom shot-noise and enables large area atom interferometry at higher data-rates. These features could prove useful for fielded inertial sensors based on atom interferometry.
by Krish Kotru.
Ph. D.
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Valdivia, Nájar Carlos Guillermo. "Calidad del tomate fresco cortado tratado por pulsos de luz (PL)." Doctoral thesis, Universitat de Lleida, 2017. http://hdl.handle.net/10803/457529.
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El tomàquet és una de les hortalisses més cultivades i amb molta importància econòmica al voltant del món. Tant l’alt valor nutritiu com la seva frescor han influït en la creixent demanda de tomàquet fresc tallat. No obstant això, durant el processament mínim del tomàquet es poden desenvolupar la reducció i pèrdua de moltes de les seves característiques. Els tractaments per llum polsada (PL) han mostrat resultats positius en la inactivació microbiana i un baix impacte en les característiques fisicoquímiques i nutricionals d’alguns aliments frescos tallats. Per això, l’objectiu principal en aquest treball va ser l’avaluació dels efectes dels PL sobre la qualitat total del tomàquet fresc laminat. De forma general es pot concloure que els tractaments de llum van ajudar a incrementar la qualitat del tomàquet tallat, mantenint el seu contingut de fitonutrients, allargant la seva vida útil i millorant els seus atributs sensorials durant l’emmagatzematge.El tomate es una de las hortalizas más cultivadas y de suma importancia económica a nivel mundial. Su elevado valor nutritivo y características organolépticas han generado una creciente demanda de alimentos procesados que mantengan las propiedades del producto fresco. Sin embargo, el procesado mínimo del tomate puede ocasionar la disminución y pérdida de muchas de sus propiedades. Los tratamientos por pulsos de luz (PL) han demostrado buenos resultados en la inactivación microbiana con un bajo impacto en las características fisicoquímicas y nutricionales de algunos alimentos frescos cortados. De este modo, el objetivo primordial de este trabajo fue evaluar los efectos de los PL en la calidad global del tomate fresco cortado. De manera general, se puede concluir que los tratamientos de PL ayudaron a incrementar la calidad del tomate cortado, manteniendo su contenido de fitonutrientes, prolongando su vida útil y mejorando sus atributos sensoriales durante el almacenamiento.
El tomàquet és una de les hortalisses més cultivades i amb molta importància econòmica al voltant del món. Tant l’alt valor nutritiu com la seva frescor han influït en la creixent demanda de tomàquet fresc tallat. No obstant això, durant el processament mínim del tomàquet es poden desenvolupar la reducció i pèrdua de moltes de les seves característiques. Els tractaments per llum polsada (PL) han mostrat resultats positius en la inactivació microbiana i un baix impacte en les característiques fisicoquímiques i nutricionals d’alguns aliments frescos tallats. Per això, l’objectiu principal en aquest treball va ser l’evacuació dels efectes dels PL sobre la qualitat total del tomàquet fresc laminat. De forma general es pot concloure que els tractaments de llum van ajudar a incrementar la qualitat del tomàquet tallat, mantenint el seu contingut de fitonutrients, allargant la seva vida útil i millorant els seus atributs sensorials durant l’emmagatzematge.
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Guay, Jean-Michel. "Multiphoton Microscopy and Interaction of Intense Light Pulses with Polymers." Thèse, Université d'Ottawa / University of Ottawa, 2011. http://hdl.handle.net/10393/20062.
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The nanoscale manipulation of soft-matter, such as biological tissues, in its native environment has promising applications in medicine to correct for defects (eg. eye cataracts) or to destroy malignant regions (eg. cancerous tumours). To achieve this we need the ability to first image and then do precise ablation with sub-micron resolution with the same setup. For this purpose, we designed and built a multiphoton microscope and tested it on goldfish gills and bovine cells. We then studied light-matter interaction on a hard polymer (PMMA) because the nature of ablation of soft-matter in its native environment is complex and not well understood. Ablation and modification thresholds for successive laser shots were obtained. The ablation craters revealed 3D nanostructures and polarization dependent orientation. The interaction also induced localized porosity in PMMA that can be controlled.
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Torres, Company Victor. "Coherence in ultrashort light pulses and applications in temporal optics." Doctoral thesis, Universitat de València, 2008. http://hdl.handle.net/10803/10124.
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In the last decades, the generation of lasers delivering pulses with durations in the order of femtosecond has constituted an important research topic for the Physics and Engineering communities. The characteristics of this kind of radiation, i.e., broadband spectrum, enormous temporal resolution, high peak-power with low energy average, potentially high repetition rate and high spatial coherence make it an indispensable tool in order to develop many applications in different fields of science and technology. Ultrafast laser technology is ready to offer real world applications ranging from high-tech, such us high-speed circuit testing and biological imaging, to more industrial applications like quality control. The markets that are already or will be influenced in the near future include industries as telecommunications, automotive, electronics, medical and inspection of consumer goods, to name only a few. In this direction, the so-called Space-Time analogy is an important tool for designing new schemes for ultrashort light pulse processing. It is based on the formal similitude between the diffraction of 1D light beams and the distortion of short light pulses in a first-order dispersive medium. In this Thesis, we have extended this analogy from the fully coherent to the partially coherent and quantum regimes. In the fully coherent regime in particular, we have proposed a new system for the tuning of spectral envelope of a short light pulse without altering the input profile. In addition, we have explained the phenomenon of phase-to-amplitude conversion in terms of the Fresnel images of a phase-only diffraction grating. In the partially coherent regime, we have made use of the optical coherence theory to analyze theoretically the influence of the finite source linewidth optical communication systems, as well as the distortion of optical frequency combs due to the general noise in mode-locked lasers. Alternatively, we have proposed and experimentally verified a technique for arbitrary radio-frequency and microwave waveform generation that operates with incoherent broadband light. Finally, in the quantum regime, we have recognized an analogy between the distortion of entangled photons and partially coherent pulses in dispersive media. This similarity has allowed us to point out that many quantum systems do not really require a two-photon light source, so that their complexity can be greatly reduced.En las últimas décadas, la generación de haces ópticos pulsados con una duración temporal del orden del pico y femtosegundo ha constituido uno de los temas de investigación más candentes en el ámbito de la Física y la Ingeniería. Los sectores que se benefician o beneficiarán de esta tecnología en un futuro cercano incluyen industrias como telecomunicaciones, automoción, electrónica, diagnóstico médico y control de calidad. Todas las potenciales aplicaciones de los pulsos ultracortos requieren de un procesado y manipulación con extremada precisión en el dominio óptico. En esta dirección, la denominada analogía Espacio-Tiempo constituye una importante herramienta para la adaptación de nuevas técnicas ultrarrápidas, basándose en la similitud formal que existe entre la difracción de haces ópticos y la distorsión de pulsos ultracortos en medios dispersivos.En esta Tesis, se ha extendido esta analogía del caso puramente coherente hasta los regímenes parcialmente coherente y cuántico. En el régimen coherente en particular, se ha propuesto un nuevo sistema para la sintonización del ancho de banda de un pulso ultracorto sin cambiar el perfil espectral. Asimismo, se ha explicado el efecto de conversión de onda continua a radiación pulsada en términos de las imágenes de Fresnel de una red pura de fase. En el régimen parcialmente coherente, se ha utilizado la teoría de la coherencia óptica para analizar teóricamente la influencia del ancho de línea en sistemas ópticos de comunicaciones, así como la distorsión de peines de frecuencia debido al ruido presente en todos los sistemas láser. Por otro lado, se ha propuesto y verificado experimentalmente una técnica que utiliza luz incoherente de banda ancha para le generación de perfiles arbitrarios de señales de microondas. Finalmente, en el régimen cuántico, se ha reconocido una similitud formal entre la distorsión de luz cuántica entrelazada tipo "dos fotones" y los pulsos parcialmente coherentes. Esto ha permitido destacar que muchos sistemas cuánticos actualmente en estudio no necesitan realmente una fuente de dos fotones, por lo que su complejidad puede ser reducida enormemente.
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DRUMMOND, ALINE MARIA DE CARVALHO. "METROLOGICAL RELIABILITY OF LASER AND INTENSE PULSED LIGHT ELECTROMEDICAL EQUIPMENT." PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO, 2007. http://www.maxwell.vrac.puc-rio.br/Busca_etds.php?strSecao=resultado&nrSeq=10706@1.
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CENTRO TECNOLÓGICO DO EXÉRCITOPara lançar equipamentos eletromédicos no mercado brasileiro, é necessária a obtenção de registro da Agência Nacional de Vigilância Sanitária, que tem por requisito a apresentação da certificação de conformidade. Na presente dissertação foram realizados estudos dos documentos normativos necessários para a avaliação da conformidade de equipamentos a laser e Luz Intensa Pulsada (IPL) para uso terapêutico, visando a análise da abrangência das normas para a garantia da confiabilidade metrológica de tais equipamentos biomédicos. Os equipamentos terapêuticos a laser precisam estar em conformidade com a Norma Geral NBR IEC 601-1, colaterais e com a Norma Particular NBR IEC 601- 2-22. O IPL, por sua vez, consiste em instrumentação óptica para uso terapêutico que não é referida na Norma Particular NBR IEC 601-2-22 e ainda não possui norma técnica específica. Verificou-se ao longo dos trabalhos para esta dissertação que, apesar da norma particular NBR IEC 601-2-22 prescrever a necessidade da medição de energia, no Brasil não existem padrões rastreáveis para calibração de medidor de energia laser. Também foi identificada a necessidade da inclusão na norma particular a avaliação das seguintes grandezas para os equipamentos a laser: divergência do feixe, duração do pulso, diâmetro do feixe de trabalho, taxa de repetição de pulso, e definição do limite máximo para o diâmetro do feixe de trabalho. Além disso, embora a norma particular não inclua os equipamentos IPL em seu escopo, esta poderia ser ampliada para adaptar-se também à avaliação deste equipamento. Para tanto, além das grandezas mencionadas acima, sugeridas para a avaliação dos equipamentos a laser, seria necessária também a avaliação de filtros que limitam os comprimentos de onda de emissão da radiação. Concluiuse também que, como a norma particular estudada recomenda o atendimento a várias cláusulas de norma não incorporada no Brasil pela ABNT - a IEC 60825-1 - cujo conteúdo é exigido para a avaliação da conformidade do equipamento, recomenda-se a complementação da norma nacional com a informação contida na IEC 60825-1. Além da inclusão de itens ao documento normativo, o presente trabalho recomenda a avaliação da incerteza da medição não somente para constar nos documentos acompanhantes, como também na avaliação de conformidade do produto. Também considerando a tolerância descrita na norma de 20% de erro da saída laser, e considerando desde já evidências apresentadas no trabalho indicando que é excessiva, recomendou-se um estudo detalhado objetivando, a partir da análise das diferentes aplicações biomédicas dos equipamentos, melhor definição de tal tolerância. Discute-se ainda sobre a importância da avaliação periódica durante o tempo de sua utilização clínica, para garantia da confiabilidade também ao longo da vida útil destes equipamentos.
Manufacturers must present a Conformity Certificate and register electrical medical products with the National Health Vigilance Agency (ANVISA) before releasing them in the Brazilian market. For medical laser equipment, the mandatory standards are the general safety standard for medical electrical equipment (NBR IEC 601-1) and the particular safety standard for diagnostic and therapeutic laser equipment (NBR IEC 601-2-22). Despite not having a particular standard with safety requirements, medical IPL equipment used for therapeutic applications are also required by ANVISA to comply with NBR IEC 601-1 and NBR IEC 601-2-22. In this thesis, the standards used for the conformity evaluation of laser and intense pulsed light (IPL) electromedical equipment were examined with the purpose of assessing their effectiveness regarding metrological reliability. It was found that, despite the energy measurement requirements in the particular standard NBR IEC 601-2-22, there are no traceable standards for optical energy measurements in Brazil. It was also found that the measurement of other quantities (such as, beam divergence and diameter, pulse duration, pulse repetition rate, among others) should be included in the particular standard. Additionally, it was found that, in order to evaluate safety requirements for medical IPL equipment, the particular standard should include requirements concerning the filters that limit the bandwidth of the radiation. In addition to including the parameters mentioned above, this dissertation also recommends the inclusion of the uncertainty in measurement not only in accompanying documents, but also in the conformity evaluation of the product. Moreover, based on evidences, discussed in this thesis, that the current acceptable error of 20% for the laser power output is extremely high, an in-depth evaluation of the actual acceptable error is recommended. Furthermore, since the particular safety standard (NBR IEC 601-2-22) refers to several clauses in the IEC 60825-1 standard, which has not yet been adopted in Brazil, it is recommended that either the IEC 60825-1 standard be adopted in Brazil, or that the clauses mentioned in NBR IEC 601-2-22 be incorporated to it. Finally, the importance of periodic postsale verifications of electromedical equipment in order to ensure metrological reliability is also discussed.
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Padgett, Nicholas C. "High Powered Pulsed Terahertz Light Generation from Superconducting Antenna Arrays." Wright State University / OhioLINK, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=wright148457888216279.
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Cooper, G. S. "Pulsed and CW waves in nonlinear optical fibre and planar waveguides." Thesis, University of Salford, 1988. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.381647.
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MacDonald, Kevin Francis. "Nonlinear optics of light-induced structural transitions in confined Gallium." Thesis, University of Southampton, 2002. https://eprints.soton.ac.uk/428199/.
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Huang, Xin. "Generation of Versatile Vortex Linear Light Bullets." University of Dayton / OhioLINK, 2015. http://rave.ohiolink.edu/etdc/view?acc_num=dayton1444754549.
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Rudhall, Andrew Peter. "Ultrashort laser pulse shaping for novel light fields and experimental biophysics." Thesis, University of St Andrews, 2013. http://hdl.handle.net/10023/3682.
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Broadband spectral content is required to support ultrashort pulses. However this broadband content is subject to dispersion and hence the pulse duration of corresponding ultrashort pulses may be stretched accordingly. I used a commercially-available adaptive ultrashort pulse shaper featuring multiphoton intrapulse interference phase scan technology to characterise and compensate for the dispersion of the optical system in situ and conducted experimental and theoretical studies in various inter-linked topics relating to the light-matter interaction. Firstly, I examined the role of broadband ultrashort pulses in novel light-matter interacting systems involving optically co-trapped particle systems in which inter-particle light scattering occurs between optically-bound particles. Secondly, I delivered dispersion-compensated broadband ultrashort pulses in a dispersive microscope system to investigate the role of pulse duration in a biological light-matter interaction involving laser-induced cell membrane permeabilisation through linear and nonlinear optical absorption. Finally, I examined some of the propagation characteristics of broadband ultrashort pulse propagation using a computer-controlled spatial light modulator. The propagation characteristics of ultrashort pulses is of paramount importance for defining the light-matter interaction in systems. The ability to control ultrashort pulse propagation by using adaptive dispersion compensation enables chirp-free ultrashort pulses to be used in experiments requiring the shortest possible pulses for a specified spectral bandwidth. Ultrashort pulsed beams may be configured to provide high peak intensities over long propagation lengths, for example, using novel beam shapes such as Bessel-type beams, which has applications in biological light-matter interactions including phototransfection based on laser-induced cell membrane permeabilisation. The need for precise positioning of the beam focus on the cell membrane becomes less strenuous by virtue of the spatial properties of the Bessel beam. Dispersion compensation can be used to control the temporal properties of ultrashort pulses thus permitting, for example, a high peak intensity to be maintained along the length of a Bessel beam, thereby reducing the pulse energy required to permeabilise the cell membrane and potentially reduce damage therein.
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Siddons, Paul. "Faraday rotation of pulsed and continuous-wave light in atomic vapour." Thesis, Durham University, 2011. http://etheses.dur.ac.uk/3218/.
Full textAbstract:
The absorptive and dispersive properties of a Doppler-broadened vapour of rubidium atoms is investigated. A detailed model of the atom-light interaction is developed and found to be in excellent agreement with experiment in the regime where the interacting light field is sufficiently weak such that it does not significantly alter the medium through which it propagates. The importance of using a weak beam to probe atomic systems is discussed, and a method of characterising how weak such a beam has to be is provided. The theoretical model is applied to both situations of illumination by continuous-wave and pulsed light, the latter situation providing a demonstration of the slow light effect. This phenomenon is a manifestation of the dispersive properties of the medium and is shown to exist over a particularly large frequency range, compared to the absorption spectrum, in thermal vapours. Off-resonant interactions are studied, in which incident laser-light is detuned from resonance to such a degree that Doppler-broadening can be neglected. We quantify the extent to which the light needs to be detuned to be in this regime, and provide approximations to the line-shape function developed in earlier parts of the thesis. The approximate line-shapes are much easier to manipulate and allow a more intuitive understanding of the atom-light interaction. In the second part of the thesis we study the Faraday effect and related phenomena which are an expression of the birefringent properties of the atom-light system. Beginning with a theoretical and experimental investigation of the Faraday rotation of a weak continuous-wave beam, we move on to the consideration of pulsed light. Optically-induced birefringence via the application of an intense continuous-wave pumping field is demonstrated experimentally, and the theoretical plausibility of controlling the polarisation state of a weak pulsed field mediated via intense pulsed light is shown.
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Witting, Tobias. "New techniques for the characterisation of femto- and attosecond light pulses." Thesis, University of Oxford, 2010. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.542994.
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Chanwattana, Thakonwat. "Generation of short pulse THz radiation from accelerator based light sources." Thesis, University of Oxford, 2016. https://ora.ox.ac.uk/objects/uuid:1e44dc39-7dbf-4ff1-bc0c-efd86a2e7ba3.
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High power and short pulse THz radiation has become increasingly important in the investigation of dynamics of organic and chemical molecules. Such radiation can be effectively generated with accelerator-based light sources. This thesis reports a series of studies on the generation of short pulse THz radiation from storage rings and from compact accelerators that can be based in University sized laboratories. The first part of this thesis reviews THz radiation, synchrotron radiation and free electron laser (FEL). The second part presents the studies of short pulse THz radiation generated from the Diamond storage ring in a new operating mode known as ultra-low alpha mode to extend spectrum of coherent radiation to higher THz frequency. The numerical simulations of a single bunch dynamics show qualitative agreements with the measurements taken at the Diamond storage ring. The third part is dedicated to the design of a compact RF linac-based THz radiation source for producing short pulse THz self-amplified spontaneous emission (SASE) FEL with an undulator and THz coherent synchrotron radiation (CSR) with a bending magnet. Start-to-end simulations of SASE FEL and CSR were performed to analyse the beam dynamics and the generation of THz radiation. The SASE FEL reaches saturation within the undulator length of 5 m, whereas the CSR spectrum covers frequency below 16 THz. In the fourth part, we investigated a THz/IR radiation source driven by a Laser Plasma Wakefield Accelerator (LPWA). Extensive 2D particle-in-cell (PIC) simulations were done to generate an ultra-short electron bunch from self-injection in a nonlinear bubble regime. The 60-MeV electron bunch was obtained with 6% energy spread and 18 mrad beam divergence. The self-injected electron beam was used to drive the SASE FEL using a normal undulator and a transverse gradient undulator (TGU) to exploit the electron bunch with large energy spread. The results show that the energy spread of 6% is too large even for the TGU. Although the energy spread is reduced to 1%, the FEL saturation cannot be reached because the bunch length of the LPWA driven beam is shorter than the FEL cooperation length. The last part of this thesis discusses the Accelerator Science Laboratory (ASL) project at the University of Oxford. The designs of THz radiation sources driven by the RF linac and the LPWA previously presented were considered as potential options for the ASL. The radiation shielding for the ASL was investigated with Monte Carlo simulations to design a proper beam dump and shielding covering the beam dump.
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Butts, David LaGrange. "Light pulse atom interferometry at short interrogation times for inertial navigation." Thesis, Massachusetts Institute of Technology, 2011. http://hdl.handle.net/1721.1/71453.
Full textAbstract:
Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Aeronautics and Astronautics, February 2012."February 2012." Cataloged from PDF version of thesis.
Includes bibliographical references (p. 141-150).
Light pulse atom interferometry with cold atoms is a promising inertial sensing technology for high accuracy navigation. At present, laboratory atom interferometers match or surpass state of the art mechanical and optical inertial sensors in terms of sensitivity and long term stability. Conventional laboratory systems, however, do not achieve sufficient bandwidth or dynamic range to operate in a dynamic environment; furthermore, the size, weight and power of laboratory sensors are unsuitable for many applications. In this thesis, atom interferometry is realized at shorter interrogation times (<15 ms as opposed to >100 ms), in which the required sensitivity, bandwidth and dynamic range of navigation systems becomes feasible. A cold atom gravimeter testbed using atom interferometry with stimulated Raman transitions was developed, which executed the entire measurement cycle in a compact vacuum cell (~ ~ 80 cc). The system demonstrated an inferred sensitivity of 2 [mu]g[square root] Hz for an interrogation time of 2T = 10 ms (based on measured phase SNR, scale factor, and repetition rate). With realistic improvements to the apparatus, it could achieve a sensitivity of <1 [mu]g[square root]Hz, advancing toward the realization of a compact, atom-based inertial measurement unit with unprecedented performance. In addition, a method for increasing the momentum splitting of Raman pulse interferometers with sequential Raman pulses was demonstrated, and interferometer area was increased by up to a factor of nine without altering the interrogation time (corresponding to a momentum splitting of 18hk, the largest reported for Raman pulse interferometry). Composite Raman pulses were implemented to improve population transfer efficiency, which limits the achievable increase in precision. Finally, the effect of coherent population trapping (CPT) induced by Raman pulse atom optics was identified as a source of systematic phase shifts in the [pi]/2 - [pi] - [pi]/2 interferometer used for sensing acceleration and rotation. CPT effects were modeled in a three-level (A) atom, and were experimentally characterized using atom interferometry. Based on the magnitude of measured coherences induced by Raman pulse atom optics, phase shifts of several milliradians should occur for a typical GHz-scale laser detuning. A method for suppressing this bias in realistic operation by Raman beam propagation direction reversal is proposed.
by David L. Butts.
Ph.D.
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Sinha, Moitreyee. "PROBING POLYMER NETWORKS USING PULSE PROPAGATION AND BRILLOUIN LIGHT SCATTERING TECHNIQUES." University of Cincinnati / OhioLINK, 2000. http://rave.ohiolink.edu/etdc/view?acc_num=ucin974213434.
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Zhang, Rui. "Propagation of ultrashort light pulses in tapered fibers and photonic crystal fibers." [S.l.] : [s.n.], 2006. http://deposit.ddb.de/cgi-bin/dokserv?idn=981255191.
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Carbonell, Leal Miguel. "Complex spatial shaping of femtosecond pulses with phase-only spatial light modulators." Doctoral thesis, Universitat Jaume I, 2020. http://hdl.handle.net/10803/668541.
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This thesis is focused on spatial manipulation of laser beams with a single phase only SLM. To achieve it, it is essential to arbitrarily modify a complex field with this kind of devices. In addition, it is intended to introduce new methods to improve existing techniques. In that sense, the experimental implementation of a method known as double-phase is improved and optimized. With that goal in mind, the behavior of SLMs is studied in order to adapt, as far as possible, the experimental response of these devices. Finally, the optimized method is used in several applications to obtain real results comparable to other well-known optical methods.La posibilidad de definir, de forma arbitraria, parámetros como el patrón de irradiancia o la fase de un haz láser ha contribuido a adecuar las fuentes de luz a los requisitos concretos de cada usuario para sus distintas aplicaciones. Como resultado, el desarrollo de nuevas técnicas que permitan realizar este tipo de control se ha convertido en un tema esencial que beneficia a gran cantidad de aplicaciones. Los moduladores espaciales de luz (SLMs por sus siglas en inglés) son dispositivos que permiten control directo de estas propiedades. Generalmente, los SLMs son capaces de modular en tiempo real y de forma programable uno de estos parámetros (amplitud o fase). No obstante, para controlar los dos parámetros al mismo tiempo es necesario el empleo de varios dispositivos o el desarrollo de alguna técnica que permita realizar este control con un solo dispositivo.
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Lamont, Yvonne. "The effects of UV-rich light pulses on pathogenic microorganisms in liquids." Thesis, University of Strathclyde, 2005. http://oleg.lib.strath.ac.uk:80/R/?func=dbin-jump-full&object_id=21595.
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The work presented in this thesis is concerned with investigating the use of UV-rich light pulses for the inactivation of problematic microorganisms. UV radiation is an effective means of disinfecting surfaces and liquids and of reducing contamination in air. The germicidal effects are primarily due to the UV-C region of the electromagnetic spectrum, which interferes with the nuclear core of a microorganism resulting in a loss of ability to replicate and initiate infection. When UV radiation is delivered as pulses of light however, the results are even more appealing, with higher levels of microbial inactivation achieved in much shorter timescales. Drinking water and wastewater disinfection is normally provided by the use of chemicals such as chlorine. These are disadvantaged by the production of harmful chemical by-products and the resistance of certain types of microorganism to chemical treatment. The main aim of this investigation was therefore to look at the role of pulsed UV-rich light for inactivating a range of microorganisms suspended in liquid media and to determine how successful the treatment process would be as an alternative disinfection method. The results show that pulsed UV-rich light treatment is extremely effective against many types of bacteria, virus and Cryptosporidium. It was also demonstrated that the sensitivities of microorganisms to UV radiation can vary significantly depending on the cell-wall structure, growth phase, strains and nucroorgarusm specIes. Studies were also undertaken to identify electrical and biological parameters that may influence the inactivation success. It was found that high operating voltages and low pulse repetition frequencies give desirable levels of inactivation Other important factors investigated were sample depth, volume and reflection. Finally, the possible limitations to pulsed UV-rich light treatment were investigated. It was found that the success of the treatment is primarily determined by the transmittance of UV pulses through a sample. As expected, transmittance depends upon microorganism size and population. The major limitation of UV treatment is the ability of microorganisms to reactivate following exposure to visible light (photoreactivation). Studies showed photoreactivation to occur following pulsed UV-rich light treatment, only when the microorganisms do not receive sufficient UV treatment or if they are exposed to high intensities of visible light.
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Avashia, Sanjiv H. "Application of intense pulsed light for surface sterilization and food quality improvement." Thesis, Virginia Polytechnic Institute and State University, 1988. http://hdl.handle.net/10919/80167.
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Flashblast™ (a registered trademark) is an intense broad spectrum pulsed light source developed by Maxwell Laboratories, San Diego, California which utilizes a Xenon flashlamp for emitting a mixed spectrum of ultraviolet, visible and infrared light. The project's objective was to determine the feasibility of ultra-high intensity light for improving food quality by reducing surface microbial contamination and selected mold metabolites (aflatoxins).
Flashblast™ light was found to be highly effective in inactivating vegetative cells of E. coli, S. aureus, B. cereus and B. subtilis. Bacilli and A. niger spores were also susceptible to Flashblast light at somewhat higher fluences.
Ultrastructural study with the scanning and transmission electron microscopes indicated that Flashblast™ treated gram-negative E. coli population is more susceptible to membrane damage when compared to other microorganisms. This suggests that photoinactivation involves effects on sensitive sites (genetic material) within the treated organisms which do not lead to significant changes in the microorganism morphology.
Food acceptability studies on cheese, bread, strawberries and turkey breasts did not show a significant alteration in color, flavor and texture (p≤0.05). The results obtained with bread and strawberries showed commercial feasibility with an approximate 50% shelf-life extension. Flashblast™ treatment caused photodegradation of most aflatoxin types when multiple flash sequences were employed.
It was concluded that full spectrum Flashblast™ light is highly effective for the inactivation of microorganisms and destruction of aflatoxins without causing undesirable sensory changes in foods.Master of Science
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Coughlan, Matthew Anthony. "Controlling Light-Matter Interactions and Spatio-Temporal Properties of Ultrashort Laser Pulses." Diss., Temple University Libraries, 2012. http://cdm16002.contentdm.oclc.org/cdm/ref/collection/p245801coll10/id/186215.
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ChemistryPh.D.
The SPECIFIC method a fast and accurate method for generating shaped femtosecond laser pulses. The femtosecond pulses are user specified from pulse parameters in the temporal domain. The measured spectral and recovered temporal phase and amplitudes from SEA TADPOLE are compared with the theoretical pulse profile from the user specified input. The SPECIFIC method has been shown to be a technique that can generate a diverse array of spectral/temporal phase and amplitude as well as polarization pulse shapes for numerous scientific applications. The spatio -temporal -spectral properties of focusing femtosecond laser pulses are studied for several pulse shapes that are important for non-linear spectroscopic studies. We have shown with scanning SEA TADPOLE that the spatio-spectral phase of focusing double pulse profile changes across the laterally across the beam profile. The spectral features of the sinusoidal spectral phase shaped pulse has been shown to tilt at with a changing angle away from the focus of the lens. Using spatio-spectral coupling, we have shown that multiple spatio-temporal foci can be generated along and perpendicular to the focusing direction of a femtosecond laser pulse. The spatial position of the spatio-temporal foci is controlled optically. Using sinusoidal spectral phase modulated pulse trains fragment ion production from Benzonitrile parent molecule can be controlled. A spectral transmission window perturbed the temporal pulse amplitudes resulting in fragment ion production dependant on spectral window position. The spectral window ion production was shown to also be dependant on temporal phase sequence.
Temple University--Theses
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Patel, Bhavesh. "X-ray diffraction and raman spectroscopy of pulsed light irradiated nanocrystalline silicon." Thesis, University of British Columbia, 2015. http://hdl.handle.net/2429/55028.
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A series of experiments is performed on a number of hydrogenated nanocrystalline silicon samples prepared through pulsed xenon light irradiation. These samples are then subjected to XRD and Raman spectroscopic analyzes. The mean crystalline size, corresponding to one of the pulsed hydrogenated nanocrystalline silicon sample, was determined from the XRD results through the use of Scherrer's equation. This yielded a mean crystallite size of 3.8 ± 1.1 nm, which is much less than that typically found in hydrogenated nanocrystalline silicon prepared through conventional means. The Raman spectra, corresponding to all of the samples, is determined using two different Raman excitation sources, 442 and 633 nm. Through a process of peak decomposition, the crystalline volume fraction is determined corresponding to each sample and each Raman excitation source. Five key observations are made from this analysis. First, it is observed that pulsing seems to enhance the crystalline volume fraction. Second, it is noted that the substrate holder temperature plays a relatively minor role, if at all, in shaping the crystalline volume fraction. Third, the crystalline volume fraction of the samples considered in this study is representative of that found in other forms hydrogenated nanocrystalline silicon. Fourth, the dependence of the crystalline volume fraction on the mean crystallite size seems to follow the general trend observed in the literature, i.e., that smaller mean crystallite sizes correspond to greater crystalline volume fractions, although further data would be required in order to confirm this trend. Fifth and finally, it is observed that the crystalline volume fractions determine from the 633 nm Raman excitation source are less than those found from the 442 nm Raman excitation source. This suggests an inhomogeneity in the material structure, with deeper materials from the surface having a reduced crystalline content. The reasons for this remain unknown at the present time. Some recommendations further study are then made.Applied Science, Faculty of
Engineering, School of (Okanagan)
Graduate
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Zaukevičius, Audrius. "The use of angular dispersion for formation of high peak power and ultrashort pulsed light beams in nonlinear interactions." Doctoral thesis, Lithuanian Academic Libraries Network (LABT), 2012. http://vddb.laba.lt/obj/LT-eLABa-0001:E.02~2012~D_20121227_090300-84220.
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This thesis is aimed to provide an extensive picture of the phenomena encountered in optical parametric amplification of pulsed light beams. The particular attention is paid for the spatio-temporal dynamics of the pulsed light beams being amplified. All the research has been done by means of numerical methods. The equations used in the model were derived from the Maxwell’s equations and the assumptions made along the derivation of equations were discussed. Using the presented model it has been numerically demonstrated, that in noncollinear optical parametric amplifier, when pulse fronts of pump and signal are not matched, the signal pulse becomes tilted and aside from angular dispersion acquires a spatial chirp. It has been shown, that the magnitudes of the induced spatial and angular dispersions decrease at different rates with the increase of the signal pulse temporal chirp. The main results of this study were verified experimentally. Additionally, in this thesis we have proposed a novel and versatile method for pulsed conical wave parametric amplification with subsequent spatio-temporal compression during propagation in free space. It allows to form ultra-intense and propagation invariant wave-packets capable to propagate over many Rayleigh range in the desired material. In contrast to ordinary chirped-pulse amplification technique it does not require a pulse compressor, thus greatly facilitates the parametric amplification of few-cycle light pulses.Disertacija yra skirta išnagrinėti ir paaiškinti impulsinių šviesos pluoštų parametrinio stiprinimo metu vykstančius reiškinius. Ypatingas dėmesys yra skiriamas erdvinei-laikinei impulsinio šviesos pluošto dinamikai stiprinimo metu. Visi nagrinėjamų reiškinių tyrimai buvo atliekami taikant skaitmeninio modeliavimo metodus. Modelyje panaudotos lygtys buvo išvestos iš Maksvelo lygčių, išsamiai aptariant lygčių išvedimo metu daromas prielaidas. Naudojantis pateiktu modeliu buvo gauti skaitmeniniai rezultatai, kurie parodė, jog nekolineariame parametriniame stiprintuve, kuomet kaupinimo ir signalinio impulsų frontai nėra sutapatinti, signalinis impulsas tampa pakrypęs ir be kampinės dispersijos taip pat įgyja ir erdvinį čirpą. Nustatyta, kad indukuotų erdvinės ir kampinės dispersijų mažėjimo sparta, didinant signalinio impulso laikinį čirpą, yra skirtinga. Pagrindiniai šio teorinio tyrimo rezultatai buvo patvirtinti eksperimentiškai. Taip pat šioje disertacijoje yra pristatomas naujas ir universalus impulsinių kūginių bangų parametrinio stiprinimo metodas, kuriame sustiprinti impulsai patys susispaudžia laike ir erdvėje paprasčiausiai sklisdami laisvoje erdvėje. Šis metodas leidžia formuoti didelio smailinio intensyvumo invariantiškus bangų paketus, galinčius nusklisti daugelį Relėjaus nuotolių norimoje medžiagoje. Priešingai nei įprastame čirpuotų impulsų stiprinimo metode, šis metodas nereikalauja impulsų spaustuvo, o tai žymiai palengvina parametrinį kelių optinių ciklų... [toliau žr. visą tekstą]
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Shen, Hanfei M. 1979. "Novel broadband light sources and pulse generation techniques at 1.5 [mu]m." Thesis, Massachusetts Institute of Technology, 2009. http://hdl.handle.net/1721.1/54645.
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Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2009.In title on title page, [mu] appear as lower case Greek letter. Cataloged from PDF version of thesis.
Includes bibliographical references.
A wide diversity of applications, in both fundamental science and practical technology, has come to rely on broadband optical light sources as key enabling tools. In this thesis, we investigate three devices that contribute to the generation of broadband light at 1.5 [mu]m. The first two fall into the same broader class of saturable absorber mirrors - one device was developed for low-repetition-rate sub-100-fs ultrafast lasers and the other for high-repetition- rate femtosecond lasers. The third device bypasses generating broadband light directly from a laser altogether through the use of extra-cavity spectral broadening in a novel highly nonlinear glass fiber. In the first category, ultra-broadband saturable absorber mirrors based on III/V and Si material systems were developed for ultrafast lasers. The III/V-based mirrors were designed, fabricated, characterized and implemented in a wide range of wavelengths, spanning the visible to the near-infrared. These mirrors exhibited high-reflectivity ranges of >300 nm. Implementation of these mirrors in Ti:sapphire, Cr4+:forsterite, Cr4+:YAG, and erbium-doped bismuth-oxide lasers demonstrated self-starting and stable modelocked operation. Saturable absorber mirrors were also developed for high-repetition-rate short-cavity femtosecond lasers, with modulation depths ranging from 1.7% to 11%. Post-growth proton bombardment was used to improve recovery times, and preliminary laser testing has yielded promising results, with all structures demonstrating modelocking in an erbium-doped fiber laser.
(cont.) Saturable absorber mirrors with integrated dispersion compensation were also designed with 750 fs2 of anomalous group delay dispersion at 1.5 [mu]m. Finally, a novel highly nonlinear bismuth-oxide glass fiber was used to generate smooth, controlled supercontinuum spanning 1200 to 1800 nm. With a 2-cm length and a grating pair for dispersion compensation, compression of 150-fs pulses down to 25-fs was also demonstrated.
by Hanfei M. Shen.
Ph.D.
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Soneson, Joshua Eric. "Optical Pulse Dynamics in Nonlinear and Resonant Nanocomposite Media." Diss., Tucson, Arizona : University of Arizona, 2005. http://etd.library.arizona.edu/etd/GetFileServlet?file=file:///data1/pdf/etd/azu%5Fetd%5F1274%5F1%5Fm.pdf&type=application/pdf.
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Hamed, Baidaa Khalifa [Verfasser]. "Multi-photon absorption process induced by ultra-fast light pulses / Baidaa Khalifa Hamed." Berlin : Freie Universität Berlin, 2015. http://d-nb.info/1080522077/34.
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Eckstein, Andreas [Verfasser], and Christine [Akademischer Betreuer] Silberhorn. "Mastering quantum light pulses with nonlinear waveguide interactions / Andreas Eckstein. Betreuer: Christine Silberhorn." Erlangen : Universitätsbibliothek der Universität Erlangen-Nürnberg, 2012. http://d-nb.info/1027850219/34.
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Langrock, Carsten. "Classical and low-light-level detection and pulse characterization using optical-frequency mixers /." May be available electronically:, 2007. http://proquest.umi.com/login?COPT=REJTPTU1MTUmSU5UPTAmVkVSPTI=&clientId=12498.
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Voronov, Sergei Leonidovich. "Controlling laser high-order harmonic generation using weak counter-propagating light /." Diss., CLICK HERE for online access, 2003. http://contentdm.lib.byu.edu/ETD/image/etd146.pdf.
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Zhang, Zhe. "Quantitative Analysis of Phase-Transition Process of Light-Activatable Theranostic Agents by Pulsed Laser." University of Cincinnati / OhioLINK, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1535705361083778.
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Erbas, Kadir Can. "Some Properties And Conserved Quantities Of The Short Pulse Equation." Master's thesis, METU, 2008. http://etd.lib.metu.edu.tr/upload/12609368/index.pdf.
Full textAbstract:
Short Pulse equation derived by Schafer and Wayne is a nonlinear partial differential equation that describes ultra short laser propagation in a dispersive optical medium such as optical fibers. Some properties of this equation e.g. traveling wave solution and its soliton structure and some of its conserved quantities were investigated. Conserved quantities were obtained by mass conservation law, lax pair method and
transformation between Sine-Gordon and short pulse equation. As a result, loop soliton characteristic and six conserved quantities were found.
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Yagci, Mahmut Emre. "Development Of A Picosecond Pulsed Mode-locked Fiber Laser." Master's thesis, METU, 2013. http://etd.lib.metu.edu.tr/upload/12615773/index.pdf.
Full textAbstract:
Fiber lasers represent the state-of-the-art in laser technology and hold great promise for a
wide range of applications because they have a minimum of exposed optical interfaces,
very high efficiency, and are capable of exceptional beam quality. In the near future, the
most important markets such as micromachining, automotive, biomedical and military
applications will begin to use this technology. The scope of this thesis is to design and
develop a short picosecond pulsed fiber laser using rare-earth doped fiber as a gain
medium. The proposed master oscillator power amplifier (MOPA) will be used to generate
pulses with high repetition rates.
In this study, first we explain the basic theoretical background of nonlinear optics and fiber
laser. Then, the numerical simulation will be introduced to explain how the laser system
design and optimization. The simulation is based on nonlinear Schrödinger equation with the method of split-step evaluation. The brief theoretical background and simulation results of the laser system will be shown. Finally, the experimental study of the developmental fiber laser system that comprises an oscillator, preamplifier and power amplifier will be discussed.
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Eigenwillig, Christoph. "New rapidly wavelength-swept light sources for optical coherence tomography and picosecond pulse generation." Diss., lmu, 2012. http://nbn-resolving.de/urn:nbn:de:bvb:19-149213.
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Rustand, Åsmund. "Ambient-light Photoplethysmography : - How can I tell your pulse from looking at your face?" Thesis, Norges teknisk-naturvitenskapelige universitet, Institutt for elektronikk og telekommunikasjon, 2012. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-18848.
Full textAbstract:
This thesis is an attempt to explore certain aspects of the subject called non-contact, ambient-light photoplethysmography, where we hope to reveal benecialproperties the technique may have. We have a clear focus on technical possibilitybut the medical relevance of it is also discussed and conrmed.Conclusions from previous work are exemplied { the ability we have with thismethod to compute an exact heart rate estimate, from the skin surface both onour face and in the palm of our hand, with and without the subject moving duringrecording; the presence of signal uctuations akin to those of breathing. Moreover,that the pulsations are strong enough to enable subdivision into smaller segmentsand a mapping of how the pulse amplitude is distributed among them.Other information is obtained: the phase information contained in the signalis robust enough that not only the average heart rate over some time but also itsshort time variability can be seen with more than a minimum of detail resolution.From a recording where both face and hand is in view, we further substantiate theclaim of phase robustness by estimating the phase delay, i.e. the dierence in bloodpressure wave travel time between forehead and palm.The concept of Independent Component Analysis has been suggested as a way ofimproving the output of the method|a procedure we investigate and nd limitedsupport for. Other, more simplistic signal processing approaches are found to havepositive traits in achieving overall signal clarity.
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Lam, Matthew Hon C. "Chirped-pulse laser amplifier and passive enhancement cavity for generation of extreme ultraviolet light." Thesis, University of British Columbia, 2010. http://hdl.handle.net/2429/27803.
Full textAbstract:
Extreme ultraviolet (EUV) light has many potential applications, including spectroscopy and scattering experiments in physical chemistry and atmospheric science. The dominant method for producing high-flux coherent radiation in this spectral range is synchrotron radiation produced from highly subscribed national-scale facilities such as the Canadian Light Source. An alternative to synchrotron radiation is high harmonic generation (HHG), a nonlinear optical process requiring high optical intensities. This thesis describes the development of an optical amplifier and passive enhancement cavity in order to realize a table-top EUV source. A chirped-pulse ytterbium-doped fiber amplifier system outputs 20 W average power from an initial mode-locked laser outputting pulses at 80 MHz and 160 mW average power. The pulses, of duration ~250 fs after the amplifier, are coupled to a high-finesse cavity which further increases the power by a factor of 500. The peak intensity achieved in the cavity is over 10¹⁴ W/cm² and is an order of magnitude above the intensity required to drive HHG in xenon gas.