Дисертації з теми "020503 Nonlinear Optics and Spectroscopy"
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Polyutov, Sergey. "Electron-nuclear Dynamics in Nonlinear Optics and X-ray spectroscopy." Doctoral thesis, Stockholm : Bioteknologi, Kungliga Tekniska högskolan, 2007. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-4339.
Повний текст джерелаLiu, Ji-Cai. "Dynamics of multiphoton processes in nonlinear optics and x-ray spectroscopy." Doctoral thesis, KTH, Teoretisk kemi, 2009. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-11394.
Повний текст джерелаQC 20100729
Lim, Daeyoung. "Nonlinear optical spectroscopy of silicon-boron and other silicon-adsorbate systems." Access restricted to users with UT Austin EID Full text (PDF) from UMI/Dissertation Abstracts International, 2001. http://wwwlib.umi.com/cr/utexas/fullcit?p3034931.
Повний текст джерелаMcGuckin, Brendan T. "Linear and nonlinear optical spectroscopy of semiconductors using opticallypumped lasers." Thesis, Heriot-Watt University, 1985. http://hdl.handle.net/10399/1655.
Повний текст джерелаBarlow, Aaron M. "Spectral Distortions & Enhancements In Coherent Anti-Stokes Raman Scattering Hyperspectroscopy." Thesis, Université d'Ottawa / University of Ottawa, 2015. http://hdl.handle.net/10393/32388.
Повний текст джерелаValley, John Francis. "Nonlinear optical experiments in sodium vapor and comparison with Doppler-broadened two-level-atom theory." Diss., The University of Arizona, 1989. http://hdl.handle.net/10150/184930.
Повний текст джерелаГрідякіна, Олександра Валеріївна, and Аркадій Петрович Поліщук. "Nonlinear-optical recording in ionic liquid crystalline medium." Thesis, Physikzentrum in Bad Honnef, 2017. http://er.nau.edu.ua/handle/NAU/32390.
Повний текст джерелаOdhner, Johanan. "INVESTIGATIONS OF TEMPORAL RESHAPING DURING FILAMENTARY PROPAGATION WITH APPLICATION TO IMPULSIVE RAMAN SPECTROSCOPY." Diss., Temple University Libraries, 2012. http://cdm16002.contentdm.oclc.org/cdm/ref/collection/p245801coll10/id/196129.
Повний текст джерелаPh.D.
Femtosecond laser filamentation in gaseous media is a new source of broadband, ultrashort radiation that has the potential for application to many fields of research. In this dissertation filamentation is studied with a view to understanding the underlying physics governing the formation and propagation dynamics of filamentation, as well as to developing a method for vibrational spectroscopy based on the filament-induced impulsive vibrational excitation of molecules in the filamentation region. In pursuit of a better understanding of the underlying physical processes driving filamentation, the development of a new method for characterizing high intensity ultrashort laser pulses is presented, wherein two laser beams generate a transient grating in a noble gas, causing the pulse undergoing filamentation to diffract from the grating. Measuring the spectrum as a function of time delay between the filament and probe beams generates a spectrogram that can be inverted to recover the spectral and temporal phase and amplitude of the filamentary pulse. This technique enables measurement of the filamentary pulse in its native environment, offering a window into the pulse dynamics as a function of propagation distance. The intrinsic pulse shortening observed during filamentation leads to the impulsive excitation of molecular vibrations, which can be used to understand the dynamics of filamentation as well. Combined measurements of the longitudinally-resolved filament Raman spectrum, power spectrum, and fluorescence intensity confirm the propagation dynamics inferred from pulse measurements and show that filamentation provides a viable route to impulsive vibrational spectroscopy at remote distances from the laser source. The technique is applied to thermometry in air and in flames, and an analytical expression is derived to describe the short-time dynamics of the rovibrational wave-packet dispersion experienced by diatomic molecules in the wave of the filament. It is found that no energy is initially partitioned into the distribution of rovibrational states during the filamentation process. Filament-assisted impulsive stimulated Raman spectroscopy of more complex systems is also performed, showing that filament-assisted vibrational measurements can be used as an analytical tool for gas phase measurements and has potential for use as a method for standoff detection. Finally, a study of the nonlinear optical mechanisms driving the filamentation process is conducted using spectrally-resolved pump-probe measurements of the transient birefringence of air. Comparison to two proposed theories shows that a newly described effect, ionization grating-induced birefringence, is largely responsible for saturation and sign inversion of the birefringence at 400 nm and 800 nm, while the magnitude of contributions described by a competing theory that relies on negative terms in the power series expansion of the bound electron response remain undetermined.
Temple University--Theses
Hu, Zhen Kimble H. Jeff Kimble H. Jeff. "Quantum optics with cold atoms--nonlinear spectroscopy and road toward single-atom trap /." Diss., Pasadena, Calif. : California Institute of Technology, 1995. http://resolver.caltech.edu/CaltechETD:etd-10112007-092812.
Повний текст джерелаGovani, Jayesh R. "Spectroscopic characterizations of organic/inorganic nanocomposites." To access this resource online via ProQuest Dissertations and Theses @ UTEP, 2009. http://0-proquest.umi.com.lib.utep.edu/login?COPT=REJTPTU0YmImSU5UPTAmVkVSPTI=&clientId=2515.
Повний текст джерелаRobertson, John Michael. "Nonlinear optical properties of absorbing molecular systems." Thesis, University of Essex, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.390961.
Повний текст джерелаБордюг, Ганна Борисівна, and Аркадій Петрович Поліщук. "Fast photoconversion in viologen-doped lyotropic ionic liquid crystals." Thesis, Physikzentrum in Bad Honnef, 2017. http://er.nau.edu.ua/handle/NAU/32391.
Повний текст джерелаPeter, F. "Advanced emitters and detectors for terahertz time-domain spectroscopy." Forschungszentrum Dresden, 2010. http://nbn-resolving.de/urn:nbn:de:bsz:d120-qucosa-61479.
Повний текст джерелаГрідякіна, Олександра Валеріївна, and Ганна Борисівна Бордюг. "Nonlinear helical winding in highly viscous chiral thin films." Thesis, NANO-2017, 2017. http://er.nau.edu.ua/handle/NAU/32389.
Повний текст джерелаKimberg, Victor. "Pulse Propagation in Nonlinear Media and Photonic Crystals." Doctoral thesis, Stockholm, 2006. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-3886.
Повний текст джерелаFu, Jie. "Molecular Structure-Nonlinear Optical Property Relationships for a Series of Polymethine and Squaraine Molecules." Doctoral diss., University of Central Florida, 2006. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/3941.
Повний текст джерелаPh.D.
Other
Optics and Photonics
Optics
Averett, Shawn C. "Advancements in the Understanding of Nonlinear Optics and Their Use in Material Analysis." BYU ScholarsArchive, 2017. https://scholarsarchive.byu.edu/etd/6507.
Повний текст джерелаOlszak, Peter D. "Nonlinear absorption and free carrier recombination in direct gap semiconductors." Doctoral diss., University of Central Florida, 2010. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/4620.
Повний текст джерелаID: 029050684; System requirements: World Wide Web browser and PDF reader.; Mode of access: World Wide Web.; Thesis (Ph.D.)--University of Central Florida, 2010.; Includes bibliographical references.
Ph.D.
Doctorate
Optics and Photonics
Rasekh, Payman. "Kerr Effect at the THz Frequencies." Thesis, Université d'Ottawa / University of Ottawa, 2020. http://hdl.handle.net/10393/41085.
Повний текст джерелаShah, Anjali. "External cavity diode lasers and non-linear optical frequency conversion in spectroscopic applications." Thesis, St Andrews, 2006. http://hdl.handle.net/10023/142.
Повний текст джерелаPeceli, 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.
Повний текст джерелаPh.D.
Doctorate
Optics and Photonics
Optics and Photonics
Optics
Delmonte, Valentin. "Spectroscopie cohérente des excitons dans des nanostructures semi-conductrices innovantes." Thesis, Université Grenoble Alpes (ComUE), 2018. http://www.theses.fr/2018GREAY015/document.
Повний текст джерелаThe evolution of technologies related to semiconductors has led to the study of the coherence of Quantum Bits (Qbits) in order to reduce the size of the components. Using nonlinear coherent spectroscopy, I was able to study the coherence properties of excitons confined in quantum dots (BQs), themselves integrated into different nano-structures. The interest of nanostructures is to increase the signal-to-noise ratio, essential in our experience. The use of nano-structures is also essential for the purpose of setting up a long-distance radiative coupling between 2 BQs.First of all, it was necessary to characterize deterministic nano-structures that make it possible to increase the yield of usable samples by preserving the signal intensity emitted by the BQs. In addition, I developed my experience to refine our ability to study close-coupling between BQs embedded in a micro-cavity. Then we tested several forms of 1D nano-structures (trumpets and ridges) in order to amplify the long-distance coupling and to understand the obstacles we will have to face. Finally a characterization of new 2D materials was realized, in order to improve our understanding of exciton dynamics in this type of materials
Johnson, Magnus. "Vibrational Sum Frequency and Infrared Reflection/Absorption Spectroscopy Studies of the Air/Liquid and Liquid/Metal Interfaces." Doctoral thesis, Stockholm, 2005. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-455.
Повний текст джерелаIsaienko, Oleksandr. "Development of ultra-broadband ultrafast infrared sources and applications to nonlinear vibrational spectroscopy of interfaces." Diss., Temple University Libraries, 2011. http://cdm16002.contentdm.oclc.org/cdm/ref/collection/p245801coll10/id/141408.
Повний текст джерелаPh.D.
Interfaces play a crucial role in the exchange of energy and matter in various physical, chemical and biological systems. A particular interest has been to study interfaces between aqueous phases and various minerals because of their importance in understanding geochemical phenomena as well as for applications such as enhanced oil recovery. The nonlinear optical technique of vibrational sum-frequency generation (SFG) spectroscopy, introduced over 20 years ago, has become a powerful tool to investigate various surfaces, in particular, mineral-water interfaces. One of the challenges of the SFG spectroscopy of aqueous surfaces is the need to tune the central frequency of relatively narrowband IR lasers through the broad range of the OH-stretch frequencies of water molecules (3000 - 4000 cm-1). We have developed a novel ultrabroadband IR laser source that generates infrared pulses in the ~2800-6000 cm-1 range (lambda~3300-1800 nm) with bandwidths Delta(nu)>1000 cm-1, and bandwidths >2000 cm-1 in the near-IR range (lambda~1000-2000 nm). Pulse front tilt of signal pulse has been corrected allowing for compression of signal pulses down to 25 fsec. Such ultrabroadband IR pulses allow us to perform SFG spectroscopy of aqueous surfaces over the entire frequency range of water molecule spectrum (extending from ~2900 cm -1 to ~3800 cm -1) simultaneously, without tuning the laser ("in one shot"). We have used this novel ultrabroadband IR source to investigate the vibrational SFG spectra of silica/water interfaces. The high signal-to-noise ratio of our spectroscopic setup has allowed us to study low-intensity features that were not studied in detail, or recognized previously in the SFG-spectroscopy investigations, including: 1) non-hydrogen bonded OH vibrations at hydrophilic silica/water interfaces; 2) combination [stretch+bend] bands of water at the silica surface appearing at ~5000-5200 cm -1. 3) Overtones of water stretching modes at silica/water interfaces. The most important conclusions from these studies are outlined below. 1. Non-hydrogen bonded hydroxyls at silica/water interface. Typically SFG-studies of mineral/water interfaces (in particular, silica/water) have focused on the most pronounced features - peaks of H-bonded hydroxyls at ~3150 and ~3450 cm -1. We have been able to systematically observe and study a weaker peak at ~3670 - 3700 cm -1. This peak becomes more pronounced as the pH of aqueous phase decreases, as well as the ionic strength increases, indicating that the hydroxyls corresponding to this spectral feature are situated in a very close proximity to the surface. Isotopic dilution experiments indicate that the 3700 cm -1 feature is not due to asymmetric OH stretches as was suggested before. Based on our results, we suggest that this spectral feature corresponds to hydroxyls of water molecules at the silica surface that cannot hydrogen bond with silanol groups because of the lower density of silanols compared to H2O. We believe this to be the first surface-specific study of non-hydrogen bonded hydroxyls at silica, a surface widely accepted as hydrophilic. 2. SFG spectroscopy of [ν(OH)+δ(HOH)] combination bands of water at silica surface. We have extended SFG spectroscopy of the interfacial hydroxyls at mineral/water surfaces into the near-IR frequency range. The studies of overtones of interfacial OH(OD) groups will provide information on the anharmonicity of such species, and thus on the energy of dissociation. In addition, the positions of the overtone frequencies of the hydroxyls are more sensitive to interactions with the environment than the fundamental stretch frequencies. Our particular focus has been to study the stretch+bend combination band nu comb nu;(OH)+delta;(HOH) of liquid water which occurs in the near-IR spectral range at ~5000-5200 cm -1. It is typically much weaker in the FTIR absorption spectra than the fundamental transitions of the OH stretches or HOH bending, similar to overtones of these modes. We have performed, what we believe to be, the first surface-specific vibrational SFG spectroscopic measurements of combination bands of water molecules at silica surfaces. SFG spectroscopy of water combination band allows access to the water bending mode (delta~1600 cm -1), which still has not been observed in sum-frequency.
Temple University--Theses
Поліщук, Аркадій Петрович, Олександра Валеріївна Грідякіна, and Ганна Борисівна Бордюг. "Matrix effec on the electrooptical properties of heptylviologen." Thesis, XXIII ISSSMC, 2017. http://er.nau.edu.ua/handle/NAU/32388.
Повний текст джерелаAtherton, Kathryn Jane. "Coherent Raman studies of optical nonlinearities in conjugated molecules and polymers." Thesis, Imperial College London, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.298790.
Повний текст джерелаMaugeri, Pearson Thomas Maugeri. "Applications of resonance Raman spectroscopy to the study of bioinorganic macromolecules." The Ohio State University, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=osu1512093478871388.
Повний текст джерелаKhan, Md Rubel. "Adsorption and Self-Assembly of Surfactants at Air-Liquid and Liquid-Metal Interfaces Studied by Sum Frequency Generation (SFG) Spectroscopy." Ohio University / OhioLINK, 2009. http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1620212735093219.
Повний текст джерелаKhan, Md Rubel. "Adsorption and Self-Assembly of Surfactants at Air-Liquid and Liquid-Metal Interfaces Studied by Sum Frequency Generation (SFG) Spectroscopy." Ohio University / OhioLINK, 2021. http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1620212735093219.
Повний текст джерелаLydiatt, Francis Peter. "Vibrational sum-frequency spectroscopy : towards understanding adsorbate behaviour on substrates relevant to the nuclear fuel cycle." Thesis, University of Manchester, 2014. https://www.research.manchester.ac.uk/portal/en/theses/vibrational-sumfrequency-spectroscopy-towards-understanding-adsorbate-behaviour-on-substrates-relevant-to-the-nuclear-fuel-cycle(3a81bdcc-75d9-4fed-a949-ad43198625be).html.
Повний текст джерелаDewan, Shalaka. "IONS AND THE STRUCTURE AND DYNAMICS OF INTERFACIAL WATER AT CHARGED SURFACES." Diss., Temple University Libraries, 2015. http://cdm16002.contentdm.oclc.org/cdm/ref/collection/p245801coll10/id/334453.
Повний текст джерелаPh.D.
The distinct structure and dynamics of interfacial water are due to a break in the extended hydrogen bonding network present in bulk water. At solid-aqueous interfaces, the presence of surface charge, which induces a static electric field, and the electrolytes, which are present in most naturally relevant systems, can additionally perturb the hydrogen bonding environment due to polarization. The interplay between the surface-charge-induced electric field and the ions in changing the structure of interfacial water has important consequences in the chemistry of processes ranging from protein-water interactions to mineral-water reactivity in oil recovery. Accessing information about the first few layers of water at buried interfaces is challenging. Vibrational sum-frequency generation (vSFG) spectroscopy is a powerful technique to study exclusively the interfacial region and is used here to investigate the role of interfacial solvent structure on surface reactivity. It is known that the rate of quartz dissolution increases on addition of salt at neat water pH. The reason for this enhancement was hypothesized to be a consequence of perturbations in interfacial water structure. The vSFG spectra, which is a measure of ordering in the interfacial water structure, shows an enhanced effect of salt (NaCl) at neat pH 6~8. The trend in the effect of salt on vSFG spectra versus the bulk pH is remarkably consistent with the enhancement of rate of quartz dissolution, providing the first experimental correlation between interfacial water structure and silica dissolution. If salt alters the structure of interfacial water, it must affect the vibrational energy transfer pathways of water, which is extremely fast in bulk water (~130 fs). Thus far, the role of ions on the vibrational dynamics of water at charged surfaces has been limited to the screening effects and reduction in the depth of the region that contributes to vSFG. Here, we measure the ultrafast vibrational relaxation of the O-H stretch of water at silica at different bulk pH, using time-resolved (TR-vSFG). The fast vibrational dynamics of water (~200 fs) observed at charged silica surfaces (pH 6 and pH 12), slows down (~600 fs) on addition of NaCl only at pH 6 and not at pH 12. On the other hand at pH 2 (neutral surface), the vibrational relaxation shows an acceleration at high ionic strengths (0.5 M NaCl). The TR-vSFG results suggest that there is a surface-charge dependence on the sensitivity of the interfacial dynamics to ions and that reduction in the probe depth of vSFG alone cannot explain the changes in the vibrational lifetime of interfacial O-H. This is further supported by the cation specific effects observed in the TR-vSFG of the silica/water interface. While the vibrational relaxation of O-H stretch slows on addition of all salts (LiCl, NaCl, RbCl, and CsCl), the degree of slowing down is sensitive to the cation identity. The vibrational lifetime of O-H stretch in the presence of different cations follows the order: Li+ < Na+ < Rb+, consistent with previous Hofmeister effect reported in vSFG spectroscopy as well as AFM measurements at silica/water interface. To provide molecular insight on the effect of surface charge density and ionic strength on the changes in interfacial water structure, Molecular Dynamics (MD) simulations were performed on water at different types of surfaces. It was shown that the properties of water near the interface, e.g., a net orientation and the depth to which this persists, depend on the degree of specific adsorption of the counter ions. Our vSFG results, along with the insights from MD simulations, highlight the importance of considering the role of ions on the solvent structure within the electric double layer region, beyond the screening effects predicted by classical electrochemical models.
Temple University--Theses
Liebel, Matz. "Understanding molecular dynamics with coherent vibrational spectroscopy in the time-domain." Thesis, University of Oxford, 2014. http://ora.ox.ac.uk/objects/uuid:e0289d80-f6e3-4e6f-817e-f8dd55d15bc4.
Повний текст джерелаRouxel, Jérémy. "A rigorous multipolar framework for nanoparticles optical properties description : theory and experiments." Thesis, Troyes, 2015. http://www.theses.fr/2015TROY0013/document.
Повний текст джерелаUsing metallic nanoparticles with a threefold symmetry thorough the study, the impact of the symmetry on the nonlinear properties is investigated. Interpretations of polarization-resolved SHG experiments indicate the importance of multipolar resonances, in particular quadrupole and octupole, to explain the strong values of the nonlinear susceptibilities in such systems. A fully irreducible formalism is then developed to treat extended objects like nanoparticles. In this formalism, the nonlinear response tensor is a discrete set of values easily constrained by symmetries instead of a field. This formalism permits to describe simply linear and nonlinear optical response from nanoparticles. Finally, time-domain experiments are conducted with the aim to connect spatial and spectral properties. These experiments allow to interpret the spectra in terms of eigenmodes
LIBRANTZ, ANDRE F. H. "Estudo comparativo da emissoes do Nd(3+) nas configuracoes 4fsup(2)5d e 4fsup(3) induzidas pela excitacao multifotonica em cristais de YLF, GLF, LLF." reponame:Repositório Institucional do IPEN, 2000. http://repositorio.ipen.br:8080/xmlui/handle/123456789/10830.
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Dissertacao (Mestrado)
IPEN/D
Instituto de Pesquisas Energeticas e Nucleares - IPEN/CNEN-SP
Zhou, Dapeng. "The Excited State Behavior of Iminium Derivatives and Their Reduced Forms." Bowling Green State University / OhioLINK, 2013. http://rave.ohiolink.edu/etdc/view?acc_num=bgsu1370525481.
Повний текст джерелаSmirni, Salvatore. "Nonlinear dynamics of microcirculation and energy metabolism for the prediction of cardiovascular risk." Thesis, University of Dundee, 2018. https://discovery.dundee.ac.uk/en/studentTheses/c551cbef-6f00-48ef-b753-ad76ac93daf4.
Повний текст джерелаFigueira, David da Silva Leocadio 1980. "Desenvolvimento de fontes de radiação coerente na região azul com lasers semicondutores para experimentos de resfriamento e aprisionamento de átomos de cálcio." [s.n.], 2004. http://repositorio.unicamp.br/jspui/handle/REPOSIP/277775.
Повний текст джерелаDissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Fisica Gleb Wataghin
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Resumo: Esta tese apresenta o desenvolvimento de fontes de radiação coerente na região do azul baseadas em lasers semicondutores para excitar a transição de resfriamento e aprisionamento 1 S0-1P1 do Cálcio, em 423nm. Foi construído um laser de diodo em cavidade estendida emitindo em g =846 nm que foi empregado em uma configuração de Cavidade Estendida de Littman, estabilizada em freqüência pela técnica de Side-of-Fringe. Parte da potência deste laser foi amplificada por um amplificador óptico semicondutor. Potências superiores a 700mW em g =846nm foram obtidas. Parte desta potência do amplificador óptico (450mw) foi duplicada em frequência para g =423nm em um cristal de niobato de potássio(KNbO3), utilizado dentro de uma cavidade óptica ressonante com a freqüência do laser. A estabilização da cavidade óptica duplicadora de freqüência foi feita pela técnica de Hansch-Coulliaud . O sistema desenvolvido alcançou potências de 60mW de radiação coerente azul. Esta fonte laser portátil deverá ser utilizada para espectroscopia, resfriamento e aprisionamento de Cálcio
Abstract: This thesis presents the development of sources of coherent radiation in the blue region of the spectrum, based on semiconductors lasers, to excite the cooling and trapping 1S0-1P1 transition of neutral calcium atoms at 423nm. A diode laser emitting at g =846 nm was employed in an extended cavity Littman configuration, and stabilized in frequency by the Side-of-Fringe technique. Part of the laser power was amplified by an optical semiconductor amplifier. Output powers above 700mW at g =846nm were obtained. Part of this amplified power (450mW) was frequency doubled to g =423nm in a potassium niobate (KNbO3) crystal, placed inside a resonant optical cavity. The lock of the doubling optical cavity was made by the Hansch-Coulliaud technique. The developed system reached powers near 60mW of blue coherent radiation at 423nm. This portable laser source will be used for spectroscopy, cooling and trapping of calcium
Mestrado
Física
Mestre em Física
ALVAREZ, Ammis Sánchez. "Armadilha magneto ótica de rubídio e mistura de quatro ondas no vapor atômico." Universidade Federal de Pernambuco, 2016. https://repositorio.ufpe.br/handle/123456789/18556.
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Facepe
Neste trabalho apresentamos a caracterização de uma armadilha magneto ótica de átomos de Rb construída em nosso laboratório, juntamente com o seu princípio de funcionamento. O resfriamento é feito com lasers de diodo e tem como mecanismo básico a força de pressão de radiação, que é gerada pelos processos de absorção e emissão de fótons, juntamente com a ação de um campo magnético e a polarização dos feixes. O sistema consiste em três pares de feixes contrapropagantes nas direções x, y e z, com polarizações s+ e s, e um campo magnético que varía linearmente no espaço. Conseguimos armadilhar aproximadamente 108 átomos com um tempo de carga da ordem de 2 seg. Em paralelo realizamos medidas de mistura de quatro ondas degenerada em um vapor de átomos de Rb, na configuração de feixes quase-copropagantes. O sinal gerado no processo não linear foi estudado em função da frequência de um dos feixes enquanto o outro tinha sua frequência fixa; e se mostrou independe de qual dos feixes esta sendo sintonizado. Medidas simultâneas da transmissão do feixe de prova indicam que o processo não linear ocorre só na transição cíclica e envolve o grupo de átomos selecionados pelo feixe de frequência fixa.
In this work we present a characterization of magneto optical trap of 87Rb atoms built in our lab, along with its operating principle. The cooling is done with a diode laser and its basic mechanism is the force of radiation pressure, which is generated by the processes of absorption and emission of photons, together with the action of a magnetic field and polarization of the beams. The system consists of three pairs of counterpropagating beams in the x, y and z directions with s+ and s polarizations, and a magnetic field that varies linearly in space. We were able to trap about 108 atoms with a charging time of approximately 2 sec. In parallel we performed degenerate four wave mixing measures in a Rb vapor atoms using a quasi-copropagating beams configuration. The signal generated in the nonlinear process was studied as a function of one of laser’s while keep the other with a fixed frequency; and it showed independent of which of the beams is being tuned. Simultaneous measurements of the transmission of the probe beam indicates that the nonlinear process occurs only in the cyclic transition and involves the group of atoms selected by the beam with fixed frequency.
Neveu, Pascal. "Propagation de lumière dans l'hélium métastable : stockage, amplification, fluctuations et bruit quantique." Thesis, Université Paris-Saclay (ComUE), 2019. http://www.theses.fr/2019SACLN044/document.
Повний текст джерелаA quantum state of light is characterized by its statistics of number of photons. These statistics can change in the presence of coherent phenomena. This PhD focuses both experimentally and theoretically on the propagation of quantum states within a room temperature vapor of metastable helium. First, we show that ultranarrow coherent population oscillations allow to efficiently store a specific quadrature of a light wave. Nevertheless, this protocol cannot be use to store the two quadratures of a light field. Indeed, the propagation conditions deteriorates its statistical properties, forbidding its use for quantum application. Secondly, we show that it is possible to generate twomode squeezed states of light in that system. High amplification can be achieved (9 dB), exploiting the strong nonlinearities enabled by coherent population trapping of a transition, and because of the energy level structure. Finally, we study atomic spin noise transfer to light polarization noise via Faraday effect. These fluctuations, probed by spin noise spectroscopy, show original behaviors that may be useful in another systems
Picot-Clémente, Jérémy. "Etude de sources supercontinuum à fibres optiques en verre de tellurite pour la spectroscopie d'absorption moyen infrarouge appliquées à la détection de gaz." Thesis, Dijon, 2015. http://www.theses.fr/2015DIJOS040/document.
Повний текст джерелаThis work focuses on the development of mid-infrared supercontinuum light sources and their application for gas detection through absorption spectroscopy. The study of supercontinuum sources is based on nonlinear ultrashort pulse propagation in tellurite glass (80TeO2-10ZnO-10Na2O) and used in three different forms, namely a thin bulk sample, a microstructured suspended-core fiber, and a tapered suspended-core fiber. These technical means adapt themselves to distinct laser sources commercially available, thus optimizing the implementation of ultrawide-band infrared light sources. Experimental observations are compared to corresponding numerical simulations, thus pointing out the different underlying physical mechanisms of supercontinuum generation. The first study reports the filamentation-induced supercontinuum source in the tellurite glass bulk sample by means of a high-energy femtosecond laser (several micro-Joules) and associated with a complete spectro-angular mapping of light distribution. Then, the main task is related to supercontinuum generation in microstructured suspended-core fibers (with or without tapering) using nano-Joule femtosecond laser sources. A complete analysis of the fiber design was performed, especially to enhance linear and nonlinear wave propagation for efficient frequency conversion processes. As a result, a supercontinuum source covering the 0.6-3.3 µm region (i.e., 400-THz spectral bandwidth) is obtained in a 10-cm tapered fiber segment. Finally, another supercontinuum source covering the 0.9-2.6 µm region, pumped by a very compact fiber laser, was developed, in particular for its application in a gas detector system. The main goal is to explore absorption lines beyond 2 µm, which are known to be more intense and then easier to detect. A complete experimental setup for supercontinuum absorption spectroscopy based on a compact multi-pass cell was successfully developed for methane detection
Noblet, Thomas. "Etude optique du couplage vibroélectronique à l'interface entre boîtes quantiques semiconductrices et molécules organiques." Thesis, Université Paris-Saclay (ComUE), 2019. http://www.theses.fr/2019SACLS272.
Повний текст джерелаThe different physico-chemical processes occurring within semiconductor quantum dots (QDs) give rise to a new class of fluorescent probes and a wide range of applications in catalysis, molecular recognition and imaging. Within these luminescent nanoparticles, the quantum confinement of electrons, which leads to their very special excitonic structure, allows us to benefit from both their absorption and emission optical properties, with the specific aim of fostering the detection and the identification of the chemical species located in their direct environment. Within this framework, we were interested in 3 to 4-nm-sized QDs composed of ternary alloys of cadmium, telluride and sulfur, and functionalized by mercaptocarboxylic ligands. In order to determine their structural, chemical and optoelectronic properties, we first characterized them thanks to several experimental techniques: electron microscopy, zeta potentiel measurements, dynamic light scattering analysis, X-ray, UV-visible and fluorescence spectroscopies. This enabled us to deduce the chemical composition of the nanocrystals, their crystal structure, size, size-dispersion, the chemical composition of their ligands, the eigenenergies of their electronic states, their transition dipole moments and absorption cross-sections. Given all those results, we succeeded in deriving an analytical model of the QD dielectric susceptibility and extracting in this way their linear response function. Then, we optimized the chemical synthesis of nanostructured interfaces made of QDs and various molecular species through the use of flat solid substrates of silicon, glass and calcium fluoride functionalized with organosilanes. These substrate/QDs/molecules interfaces were studied by linear UV-visible absorption spectroscopy and by sum-frequency generation non-linear optical spectroscopy (SFG). The former allowed us to determine the surface density of the deposited QDs and to characterize their stability over time, while the later, which combines two visible and infrared lasers, enabled us to identify the vibrational signature of the QD ligands. Thanks to those samples probed by two-colour SFG spectroscopy, we therefore shew the existence of a vibroelectronic coupling between QDs and their molecular surroundings. Especially, we demonstrated that the vibration amplitudes associated to the molecular modes of the QD ligands and the organosilanes grafted on the substrates are maximum when the QDs are excited by visible light into their first excitonic state. This experimental demonstration is further supported by theoretical considerations: Feynman diagrams in Matsubara imaginary-time representation were used to determine the analytical expression of the second-order nonlinear susceptibility of the QD/molecule bipartite system. We thus verified that the hypothesis of a dipolar coupling between QDs and molecules resulted in a modeling of the vibrational SFG response which proved to be in complete agreement with the experimental measurements. Thus, we evidenced the existence of a dipolar vibroelectronic coupling between quantum dots and molecules
Armougom, Julie. "Nouvelles sources optiques pour la détection d’espèces chimiques dans la bande III." Thesis, Université Grenoble Alpes (ComUE), 2018. http://www.theses.fr/2018GREAT077/document.
Повний текст джерелаLaser spectrometry by differential absorption is a well-known technique for standoff detection of chemical species in the atmosphere. The longwave infrared region (LWIR), ranging from 8 to 12 µm is particularly interesting because the absorption bands of many chemical species are intense and non-overlapping. In order to detect those species in the LWIR, there is a need for sources that are spectrally narrow, widely tunable, and delivers high energies. The sources based on second order nonlinear optics are the only technology able to meet those requirements. In this work, we will present the experimental results on two parametric architectures that allows emission in the LWIR for lidar measurements. The first one consists in emitting a beam directly in the LWIR by pumping nonlinear crystals with 2 µm pump lasers. The second architecture consists in amplifying the signal and idler beams coming from a 2 µm OPO, before converting them into the LWIR by difference frequency generation. Those sources are based on the association of new technologies and have the potential to offer a viable solution to a lack of sources emitting in the LWIR
Cheminal, Alexandre. "Ultrafast energy conversion processes in photosensitive proteins and organic nanostructures for photovoltaic applications." Thesis, Strasbourg, 2015. http://www.theses.fr/2015STRAE012/document.
Повний текст джерелаFemtosecond transient spectroscopies are used to investigate photonic energy conversion inorganic systems. These techniques allow to observe the ground and excited states of themolecules at the timescale of the photoreactions. It is used to understand the inter- andintramolecular energy and charge transfers leading to the desired photochemical process.The natural photoswiching retinal protein Anabaena sensory Rhodopsin is studied to understand the key parameters ruling the isomerisation quantum yield. We could determine the isomerisation quantum yield of both stable forms and their dynamics in the very same experimental conditions.Charge generation is investigated in small molecule bulk heterojunction active layers for organic solar cells made of PCBM and a BODIPY dye-derivative donor. The influence of the active layer morphology on charge generation is studied. The charge generation is limited by charge recombination but also by exciton diffusion to the donor-acceptor interface. The active layer morphology has to be improved to achieve more efficient organic solar cells with these materials
Louot, Christophe. "Sources de supercontinuum pour la microspectroscopie Raman cohérente large-bande." Thesis, Limoges, 2018. http://www.theses.fr/2018LIMO0015/document.
Повний текст джерелаCoherent Raman microspectroscopy (CARS) is an optical method used to identify molecular bonds in a sample in order to analyze and determine its complete composition. It requires the simultaneous excitation of the sample by two waves (the pump wave and the Stokes wave) in order to induce resonant vibration of the bond to be detected. For multiple bonds analysis (broadband coherent Raman microspectroscopy our Multiplex-CARS), the monochromatic Stokes wave must be replaced by a broadband beam (supercontinuum). The aim of this thesis was to design supercontinuum sources optimized for Multiplex-CARS application, in particular in terms of spectral bandwidth and spectral power density. Supercontinuum generation was investigated in three different optical fibers: (i) a microstructured single mode fiber with a large Yb doped core in which the input beam was re-amplified all along its propagation; (ii) a conventional singlemode fiber pumped in the normal dispersion regime in which spectral broadening was achieved by means of Raman gain saturation; (iii) a conventional graded-index multimode fiber in which the beam spectrally broadened by Raman gain saturation at very high power also experienced spatial self-cleaning by Kerr effect, resulting in a high brillance output beam with an,intensity profile close to that of the fundamental mode. A complete spectrotemporal study is achieved for each of these three sources
Derbazi, Maqboula. "Étude des caractéristiques Raman et optique non-linéaire des bronzes de tungstène quadratiques (A6M2M’8O30)." Thesis, Reims, 2013. http://www.theses.fr/2013REIMS041.
Повний текст джерелаRecently, very significant research has been devoted to the study of ferroelectric compounds of tetragonal tungsten bronze (TTB). This thesis deals with the synthesis and characterization of 7 TTB's material with general formula A6M2M'8O30 (A = Sr2+, Ba2+ or Pb2+, M = Ti4+, Zr4+ or HF4+, M '= Nb5+ or Ta5+). These crystalline compounds of large size ~ 100 nm were synthesized in powder form. The experimental Technics: X-ray diffraction, Raman spectroscopy, scanning electron microscopy SEM and TEM and nonlinear optics NLO, allowed us to establish close relationships between structure and physical properties. The nonlinear 2nd and 3rd order optical susceptibility χ(2), χ(3) of all compounds were determined and the resulting values of χ(3) did not show the same characteristics as measures of χ(2) because the THG signal is less dependent on the structure where SHG signal requires a non-centro-symmetric medium. The frequency shift between the vibration modes of structures containing strontium (Sr) and those based on Barium (Ba) has been detailed to identify signatures of these specific compounds. The interpretation of these powders wasn't that easy as these peaks are very delicate but our experimental results clearly show that the positions of the peaks can be modified by the change in cation materials, as long as the crystal lattice is more rigid, more we get discernible Raman modes. This difference is clearly visible where the emission is around 808 cm-1 for the structure Sr, whereas the Br it is centered around 780cm-1. We attribute these Δσ (28cm-1) to the transition of spatial symmetry group from Pba2 to P4bm. Results showed the wide variety of settings in which it is possible to act in order to optimize the compositions for a specific application
Abd, Alrahman Chadi. "Spectroscopie Laser avec des cavités résonantes de haute finesse couplées à un peigne de fréquences : ML-CEAS et vernier effet techniques. Applications à la mesure in situ de molécules réactives dans les domaines UV et visible." Thesis, Grenoble, 2012. http://www.theses.fr/2012GRENY095/document.
Повний текст джерелаThe atmospheric chemistry community suffers a lack of fast, reliable and space resolved measurements for a wide set of reactive molecules (e.g. radicals such as OH, NO3, BrO, IO, etc). Due to their high reactivity, these molecules largely control the lifetime and concentration of numerous key atmospheric species, and may have an important impact on the climate. The concentrations of such radicals are extremely low (ppbv or less) and highly variable in time and space, which imposes a real challenge during the detection. In the first part of this thesis, a compact, robust and transportable UV spectrometer is developed, exploiting the Mode-Locked Cavity Enhanced Absorption Spectroscopy (ML-CEAS) technique to measure pptv and sub-pptv levels of atmospherically important reactive molecules, in particular, halogen oxide radicals, to respond to the emerging needs. The ML-CEAS technique is based on coupling a Mode-Locked femtosecond laser to a high finesse optical cavity, which acts as a photon trap to increase the interaction between the light and the intracavity gas sample, which highly enhances the absorption sensitivity. The detection limit obtained for the IO radical is 20 ppqv (part per quadrillion), which is an impressive result. In the second part of this thesis, a new spectroscopic technique is developed, called Vernier effect, which is also based on the interaction between a mode-locked femtosecond laser with a high finesse optical cavity. This technique provides detection sensitivity similar to that of ML-CEAS technique, but the advantage is that the number of the spectral elements is given by the cavity finesse, so it can reach ten thousands, as well as this technique has a simple setup, where the spectrograph is replaced by a photodiode. Additionally, the time required to measure one output absorption spectrum can be less than 1 ms
Wetzel, Benjamin. "Etudes expérimentales et numériques des instabilités non-linéaires et des vagues scélérates optiques." Phd thesis, Université de Franche-Comté, 2012. http://tel.archives-ouvertes.fr/tel-01002680.
Повний текст джерелаVigouroux, Hélène. "Etude de vitrocéramiques optiques pour le doublement de fréquence." Phd thesis, Université Sciences et Technologies - Bordeaux I, 2012. http://tel.archives-ouvertes.fr/tel-00806577.
Повний текст джерелаSebastian, Ananthu. "Noise dynamics in multi-Stokes Brillouin laser." Thesis, Rennes 1, 2020. http://www.theses.fr/2020REN1S068.
Повний текст джерелаStimulated Brillouin Scattering (SBS) is a coherent interaction process in which light is scattered from optically generated acoustic waves. It is a powerful tool for microwave and optical signal processing, distributed sensing and spectroscopy. Brillouin lasers are attracting a lot of interest for their ability to produce ultra coherent linewidths. This thesis is devoted to the understanding of noise properties of Brillouin fiber ring lasers, operating with multiple Stokes orders. First, we present a technique based on the cavity ring-down method, which allows to characterize the Brillouin gain coefficient directly from probing the laser cavity. Its advantages are to obtain parameters from a single experiment with low optical powers (some 10 milliwatts) for short cavities (a few meters long, or integrated cavities). Secondly, it is shown that an intrinsic linewidth of a few tens of mHz can be easily obtained by cascading two non-resonant Brillouin lasers (for which the pump performs a single pass inside the cavity). In order to obtain these results, the long-term stability has been improved by using a Pound-Drever-Hall servo loop, which allows us to compare our analytical and experimental results. Unfortunately, we were unable to explore the fundamental limits of noise reduction due to the noise floor of our bench. Thirdly, one of the major works of this thesis is the theoretical and experimental study of the noise properties, including frequency noise and relative intensity noise, of a resonant Brillouin laser (for which pump and Stokes waves are resonant inside the cavity). In particular, the impacts of the fiber-ring-cavity quality factor, Brillouin gain detuning, are evaluated very precisely on the laser RIN features such as amplitude noise reduction and relaxation frequency. We emphasize the fact that many characteristics of the frequency noise are related to the RIN properties by a coupling between intensity and phase. We show that the cascade process modifies the dynamics of the Brillouin laser when compared to those of a single-mode Brillouin laser with a single first-order Stokes component. Our experimental results are in excellent agreement with our numerical simulations, obtained thanks to our non-linear system describing the operation of a multi-Stokes Brillouin laser. This good match is mainly due to our ability: to obtain very precise values of the cavity parameters and the Brillouin gain coefficient using the CRDM technique ; to achieve long-term stability (hours); to finely control the detuning between the laser Stokes resonance and the frequency of the Brillouin gain maximum. We demonstrate experimentally for the first time that frequency noise is degraded in the presence of anti-Stokes Brillouin scattering. We also show that a gain detuning of the order of a few hundred kHz can degrade the intensity noise reduction or also increase the linewidth by amplitude-phase coupling. All these very fine observations thus allow us to set the fundamental limits of such laser systems such as: the increase in noise due to anti-Stokes orders; the role of pump noise and its possible interrelation with cavity finesse; the effect of the detuning inherent to higher Stokes orders. All these conclusions are key to the design and engineering of these Brillouin fiber lasers, which are currently attracting a great deal of interest as evidenced by the work in progress in the scientific community. This PhD thesis contributes to a better understanding of multi-Stokes Brillouin lasers
Liu, Yu-Mei, and 劉玉美. "Studies of Nonlinear Optics and Spectroscopy." Thesis, 1993. http://ndltd.ncl.edu.tw/handle/15263895012306776664.
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