Tesi sul tema "Spectroscopie à cavité optique"
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Suas-David, Nicolas. "Jets hypersoniques sondés par temps de déclin d’une cavité optique : application à l’astrophysique de laboratoire". Thesis, Rennes 1, 2016. http://www.theses.fr/2016REN1S009/document.
A huge quantity of infrared spectra is collected by terrestrial and space telescopes from cool astrophysical objects (500-3000 K) like exoplanet (hot Jupiter) and brown dwarf atmospheres or circumstellar envelop of AGB stars. The main purpose of this thesis connected to experimental astrophysics is to provide high temperature data of key molecules by reproducing in the laboratory some aspects of such environments. A new setup built in Rennes couples a High Enthalpy Source to a highly sensitive Cavity Ring-Down Spectrometer. The gas studied, heated in the reservoir up to 2000 K, is expanded in a vacuum chamber through a circular nozzle and the resulting hypersonic jet can be probed at any location. Computational flow dynamics (CFD) calculations associated to a modeling of the infrared absorption lead to synthetic lines which are in very good agreement with the observed spectra. These numerical data were used to attribute the unusual double peak line shapes to the particular flow structure of axisymmetric hypersonic jets. Strong out-of-equilibrium conditions were evidenced in the isentropic core of the expansion. High vibrational temperature (1350 K) and rotational temperature lower than 10 K were recorded inside a jet of CO seeded in Ar. This degrees-of-freedom decoupling greatly simplifies the rotational structure of the recorded infrared spectra and unveils the presence of hot bands stemming from highly excited vibrational states which are significantly populated at high temperature. Our approach is therefore well suited for the study of rotationally cold hot bands of polyatomic molecules which are virtually missing in spectroscopic databases. A complementary approach consists in probing the shock layer formed upstream of an obstacle set perpendicularly to the hypersonic flow axis. Rotational temperature raises abruptly downstream the shock, revealing transitions associated with high J quantum numbers. These two methods were successfully applied to methane which plays an important role in numerous astrophysical environments. In addition to the acquisition of infrared spectroscopic data, the relaxation of internal degrees-of-freedom of CO seeded in different carrier gases (Ar and He) was studied by following the evolution of rotational and vibrational temperatures along the flow, in the isentropic core as well as in the peripheral viscous layers. These temperatures were compared to excitation temperatures calculated by an ab initio method in order to validate collision rates. These data will feed databases needed for the development of radiative transfer codes with a view to a better modeling of spectra observed from "hot" astrophysical environments
Colombier, Léo. "Spectroscopie optique de nanotubes de carbone : complexes excitoniques et cavités plasmoniques". Thesis, Montpellier 2, 2014. http://www.theses.fr/2014MON20058/document.
This thesis focus on both the biexciton's stability in carbon nanotubes, and the control of the nanotube emission through its coupling to plasmonic antenna.We report the first observation of biexciton in carbon nanotubes by means of spectral holeburning nonlinear optical spectroscopy. More precisely, two induced absorption lines are detected and assigned to trion and biexciton after investigation of their temperature and pump power dependences. An additional proof of the detection of the biexciton, as an elementary excitation of carbonnanotubes, is given in a three-beam configuration based on a two-pump scheme. The biexciton of the (9,7) chirality is observed with a binding energy of 107 ± 1 meV and shows an asymetric Fano lineshape. A first estimation of the biexciton's recombinaison dynamics is given by the quantitative analysis of the nonlinear signal. Our analytic model is formulated in the framework of the chi(3) nonlinear response, including coulomb interaction between biexcitons and free electron-hole pairs lying in the first Van Hove singularity. A Fano factor of about q = 5 is determined, which drives us to the estimation of biexciton's Auger recombinaison rate B ∈ [0.1; 1] μm · ps−1 . The Biexciton's radiative yield is then estimated of the order of 10−6 .In order to study nanotubes in plasmonic cavities, we developed micro-photoluminescence and dark-field spectroscopy experiments in the optical fiber telecommunication wavelengths (1.3 μm and 1.55 μm). Caracterisation of nanotube samples and plasmonic antenna are presented. Preliminary results on nanotubes inserted in a patch antenna have shown correlation between antenna's position and the spatial distribution of luminescence. Moreover, a change in the carbon nanotube's photoluminescence profile is observed. These results appear to be a turning point in our work. The calibration of our experiment is at its end and studies of optical properties of carbon nanotubes coupled to plasmonic antenna are now on stream in our team
Rutkowski, Lucile. "Couplage Vernier d'un peigne de fréquences femtoseconde dans une cavité optique pour la spectroscopie moléculaire très large bande". Thesis, Lyon 1, 2014. http://www.theses.fr/2014LYO10229/document.
Femtosecond mode-Locked lasers are generators of optical frequency ‘combs’, whose distinct frequencies cover many tens or hundreds of THz. My PhD work has focused on the study and construction of a particular coupling scheme in an optical cavity, named Vernier coupling. Here, the laser comb and the cavity resonances are deliberately mismatched, as a Vernier rule. This creates Moiré pattern in the cavity spectral transmission, with a periodicity related to the inverse of the mismatch. The first part details the theory behind the coupling of laser and optical cavity modes. Two regimes are identified, called “high” resolution Vernier filtering, when the laser comb structure is probed mode by mode, and “low” resolution filtering where the linewidth of one Vernier order is given by the mismatch. The second part describes the experimental realization of this coupling scheme. It details the locking strategy used to control the resonance position of the cavity (F=3000) in regards of the laser comb (kHz scale). Finally, I present spectra recorded with this setup, focusing on molecular spectroscopy. The spectra of ambient air are recorded in acquisition times around 1 s, that cover the full bandwidth of the femtosecond laser ( 40 THz, 750-850 nm), at 2 GHz resolution. The sensitivity of the absorption measurement reaches 10−9 /cm, with averaging. This high sensitivity comes from an immunity to the frequency-To-Amplitude noise conversion of the “low” resolution Vernier coupling, leading to a signal to noise ratio better than 104. These performances give the spectrometer figure of merit of 4×10−11 cm−1/√ Hz, currently taking third place in rank international state of the art ranking
C̆ermák, Peter. "Spectroscopie optique de haute sensibilité dans les plasmas et les gazes". Grenoble, 2010. http://www.theses.fr/2010GRENY029.
The project of this thesis was developed as a joint supervision project between the Department of Experimental Physics at Comenius University in Bratislava and Laboratoire de Spectrometrie Physique at Joseph Fourier University in Grenoble. The aim of the project is the development and application of some of these new spectroscopic methods for the study and diagnostics of gases and plasma. In Bratislava the work under the supervision of prof. Pavel Veis and Doc. Peter Macko was oriented towards the optical diagnostics of plasma environments. Beside the principal experiments concerning the dielectric barrier discharge (DBD) and production of the singlet oxygen state, the goal was to develop spectroscopic methods capable of providing physical measurements related to this applications. In the DBD the interest was focused on the description of the excited electronic states population variations during the period of discharge. We used fast broad--band emission spectroscopy (FEBS) comprising the instrument and data treatment process to achieve this goal. In case of singlet oxygen production we developed a Cavity ring--down spectrometer (CRDS) to detect the singlet oxygen by its infrared absorption in the microwave plasma afterglow. In Grenoble under the supervision of Dr. Daniele Romanini the principal line of work consisted in the development of a new laser source - Vertical external cavity surface emitting laser (VECSEL) and its application to absorption spectroscopy. The work was held in collaboration with the Institude d'electronique du Sud in the frame of the joint ANR MIREV project. A period was also dedicated to the developing of a small, fast, robust and low-cost NO2 and NO3detector based on the Incoherent broad--band cavity enhanced absorption spectroscopy (IBB--CEAS)
Avoine, Amaury. "Etude optique de cristaux photoniques : opales et cavités 2D". Phd thesis, Université Pierre et Marie Curie - Paris VI, 2011. http://tel.archives-ouvertes.fr/tel-00671221.
Triki, Meriam. "Cavités optiques de haute finesse pour la mesure de composés à l'état de trace en phase gazeuse". Phd thesis, Université Joseph Fourier (Grenoble), 2008. http://tel.archives-ouvertes.fr/tel-00331642.
D'abord, les notions nécessaires à la compréhension des techniques considérées sont présentées. Suit la description du développement d'un système IBB-CEAS avec une source LED émettant autour de 643 nm, avec application à la détection des oxydes d'azote à l'état de traces. Les résultats obtenus mettent en avant les avantages de cette technique en termes de simplicité, robustesse et de compacité. La limite de détection obtenue pour le radical NO2 est estimée à 1 ppbv pour deux minutes de temps d'acquisition.
Pour la deuxième étude concernant une source laser de type VECSEL émettant à 2.3 μm et pompé optiquement, le résultat principal a été l'obtention d'un balayage monofréquence sur une grande plage spectrale de l'ordre de 16.5 cm-1. Cela a demandé un balayage simultané de la température et de la longueur de la cavité laser. Ensuite, des essais préliminaires on été effectués pour coupler cette source avec la technique OF-CEAS. Ces essais ont révélé un problème de stabilité du comportement monofréquence de la source VECSEL en présence de rétroaction optique.
Enfin, la faisabilité de la technique OF-CEAS avec une source ECDL émettant dans l'infrarouge proche pour le diagnostic des décharges à basse pression a été démontrée. Le coefficient d'absorption minimale obtenu est de l'ordre de 10-9 cm-1 pour un temps d'acquisition court (0.1 s), valeur typique atteinte auparavant dans divers systèmes OF-CEAS. Des essais ont été réalisés avec une décharge en flux d'argon avec des traces de méthane autour de 1 mbar. Le même niveau de bruit a été observé que sans décharge. Cependant, dans la gamme spectrale accessible avec le ECDL disponible, les radicaux de type CHX produits dans ce type de décharge n'ont pas été détectés.
Cermak, Peter. "Spectroscopie optique de haute sensibilité dans les plasmas et les gazes". Phd thesis, Université de Grenoble, 2010. http://tel.archives-ouvertes.fr/tel-00564511.
Goblot, Valentin. "Polariton quantum fluids in one-dimensional synthetic lattices : localization, propagation and interactions". Thesis, Université Paris-Saclay (ComUE), 2019. http://www.theses.fr/2019SACLS016/document.
Semiconductor microcavities have emerged as a powerful platform for the study of interacting quantum fluids. In these cavities, light and electronic excitations are confined in small volumes, and their coupling is so strongly enhanced that optical properties are governed by hybrid light-matter quasiparticles, known as cavity polaritons. These quasiparticles propagate like photons and interact with their environment via their matter part. They can macroscopically occupy a single quantum state and then behave as an extended coherent nonlinear wave, i.e. as a quantum fluid of light. In this thesis, we study the nonlinear dynamics of polariton quantum fluids in various one-dimensional microstructures. The possibility to etch microstructures out of planar cavities, a technology developed at C2N, allows full engineering of the potential landscape for the polariton fluid, and implementing complex geometries. In a first part, we have studied the localization properties of the eigenstates in synthetic quasiperiodic lattices. Theoretical exploration of the localization phase diagram revealed a novel delocalization-localization transition in an original deformation of a quasicrystal and we have experimentally evidenced this transition. A second part of the thesis is dedicated to the study of the nonlinear dynamics of two counterpropagating polariton fluids in a one-dimensional channel. The interplay between kinetic and interaction energy is responsible for the formation of dark solitons, whose number and position can be controlled by optical means. We have evidenced a bistable behaviour controlled by the phase twist imprinted on the two fluids. The last part of this work addresses the study of nonlinearities for a fluid injected in a flat band. Therein, the kinetic energy of the fluid is quenched, so that propagation is frozen. We then observe the formation of nonlinear domains with quantized size. This work opens us exciting perspectives, specifically towards the exploration of topological phases of interacting bosons. Enhancing interactions would also allow using our platform for quantum simulation
Carlon, Zambon Nicola. "Chirality and nonlinear dynamics in polariton microresonators". Thesis, université Paris-Saclay, 2020. http://www.theses.fr/2020UPASS053.
Semiconductor microcavities, defined by a planar Fabry-Perot cavity embedding a quantum well, allow tightly confining both optical and electronic excitations. In these heterostructures, light and matter interact so rapidly that the fundamental excitations of the system can be effectively described as hybrid light-matter quasiparticles, called exciton-polaritons. Polaritons inherit properties from both their elementary constituents: the photonic modes can be tailored by molding the refractive index landscape via dry etching processing, while the excitonic component endows the system with a large Kerr nonlinearity. In this thesis, we take advantage of these two key features to engineer the photon modes using coupled micropillar resonators, and probe diverse non-linear phenomena. In the first part of this work, we consider coupled microcavities arranged in a ring geometry. Harnessing an analogue spin-orbit coupling and the ability to spin-polarize the optical gain, we demonstrate lasing in modes carrying a net orbital angular momentum (OAM), with a chirality which can be optically controlled. In addition, we evidence a bistable behaviour of the microlaser, involving modes presenting distinct OAM values and polarization patterns. In the second part of the thesis, we concentrate on the nonlinear dynamics of the system under resonant pumping. We trigger a parametric instability in coupled nonlinear resonator, and investigate the underlying mechanism. In the unstable regime, we observe the onset of sustained parametric oscillations, which presence is revealed by the appearance of bright and contrasted sidebands in the emission spectrum. In the last part of the thesis, we investigate the optical metastability a highly nonlinear single micropillar cavity, which manifests in stochastic jumps of the cavity occupation between the two -otherwise stable- branches of the classical bistability. For specific driving conditions, we observe a critical slowing down of the metastable dynamics, which is associated to the onset of a dissipative phase transition. Using a scaling analysis involving dynamical hysteresis experiments, we retrieve the critical exponents of the phase transition. Finally, we propose a mapping of the metastable dynamics of a Kerr resonator onto a logical bit subject to random bit-flip events. We can define and measure the entropy production at a single trajectory level during dynamical hysteresis experiments. These measurements allow validating an integral fluctuation theorem for the non-equilibrium entropy production. This work covers a variety of topics, from fundamental non-linear dynamics in a photonic system, to novel ideas for realizing optical devices, which could eventually operate at room temperature
Laurent, Philippe. "Stabilisation en fréquence de diodes lasers par couplage optique résonant sur une cavité Fabry-Pérot confocale". Paris 11, 1989. http://www.theses.fr/1989PA112396.
We report our work on diode laser frequency stabilization emitting near 850 and 1300 nanometers. In first, we demonstrate a single-mode operation from an initially multimode diode laser with an optical feedback on an external mirror. Secondly, a confocal Fabry-Perot cavity is used to feedback the beam from the diode laser and provide resonant optical stabilization of the semiconductor laser. We present a detailed theoretical analysis of the static and dynamic frequency noise power spectrum of the coupled cavity laser field. Experimentally we achieve static frequency noise reduction of 50-60 dB and obtain a dramatic reduction of the laser line with from 20 MHz to a few kHz. The frequency tenability of these coupled cavity diode lasers are achieved by a double servo-loop system and we have obtained a continuously frequency tuning of 7 GHz without laser spectral purity degradation. Applications of these techniques include optical pumping Cesium docks and frequency synthesis in the visible
Golebiowski, Dariusz. "High resolution FTIR spectroscopy using a femto-OPO laser source and cavity enhanced absorption". Doctoral thesis, Universite Libre de Bruxelles, 2015. http://hdl.handle.net/2013/ULB-DIPOT:oai:dipot.ulb.ac.be:2013/221150.
Doctorat en Sciences
info:eu-repo/semantics/nonPublished
Thiébaud, Jérôme. "Développement d'un spectromètre à cavité optique de haute finesse couplé à la photolyse laser : mesures spectroscopiques et cinétiques du radical HO2". Lille 1, 2007. https://pepite-depot.univ-lille.fr/LIBRE/Th_Num/2007/50376-2007-Thiebaud.pdf.
Graciani, Guillaume. "Three-dimensional stochastic interferometry : theory and applications to high-sensitivity optical metrology and light scattering amplification Random dynamic interferometer:cavity amplified speckle spectroscopy using a highly symmetric coherent fieldcreated inside a closed Lambertian optical cavity 3D stochastic interferometry detects picometer dynamics of an optical volume Cavity Amplified Speckle Spectroscopy expands lightscattering methods to transparent or miniature samples Super-resolution provided by the arbitrarily strongsuperlinearity of the blackbody radiation". Thesis, Institut polytechnique de Paris, 2020. http://www.theses.fr/2020IPPAX058.
The power of optical metrology generally requires simple geometries with precise alignment and well controlled optical phases. In the present thesis, we develop instead the notion of chaos interferometry, using an optical field with maximal geometric disorder and phase randomness. We show that stochasticity leads to a very high interferometric sensitivity and opens up the possibility for a wide range of new optical measurements and a new method we call Cavity Amplified Speckle Spectroscopy.The key idea is to inject a very small bandwidth monochromatic laser into a cavity with high albedo Lambertian reflectivity, which acts as a high-gain random resonator. A 3D coherent Lambertian billiard is obtained, filled with a 3D random field that is statistically uniform in space and invariant by rotation. At any given point P, it can be described as the coherent superposition of a large number of plane waves randomly taken from a unique statistical distribution that independently combines (1) a spherically symmetric distribution of the wave vector on a sphere ||k||=k0, with (2) a uniform distribution of the phase on [0,2pi], and (3) a uniformly distributed polarization state on the Poincarré sphere. The resulting random 3D speckle pattern remains constant with time as long as the diffusion of the laser’s wavelength can be neglected. At longer times however, it behaves ergodically. This work represents the first experimental realization of the notion of a 3D random field proposed by Berry, and it also relates to the investigations on classical light entanglement. The concepts of high-gain random resonator, or coherent Lambertian billiard, correspond to a new kind of field in optics, that obeys neither the wave equation nor the diffusion equation, and should lead to new theoretical and experimental investigations.Practically, with a slow enough diffusion of the input phase and a small enough photon-number noise, the speckle intensity field fluctuates and becomes ergodic only if the geometry of the cavity is not constant, or if it contains a medium with a non-constant optical path length distribution or polarization. Using intensity decorrelation spectra obtained between 100 MHz and 0.01 Hz from single speckles, we show the possibility to measure picometer variations of the cavity geometry and to detect sub-angstrom motion of scatterers in solutions. Chaos interferometry can also be used to amplify previously undetectable scattering signals, and we show a miniaturized light scattering setup working with microliter volumes and quasi-transparent systems. A patent was filled for a range of applications including seismic and acoustic vibration sensing, laser phase noise characterization and measurements of highly diluted and poorly scattering samples
Lengignon, Christophe. "Développement d'un système de mesure de radicaux hydroxyles par spectroscopie d'absorption en cavité résonante hors axe". Phd thesis, Université du Littoral Côte d'Opale, 2012. http://tel.archives-ouvertes.fr/tel-00874400.
Gachet, David. "Microscopie CARS (Coherent anti-Stokes Raman scattering). Génération du signal au voisinage d'interfaces et à l'intérieur d'une cavité Fabry-Perot". Aix-Marseille 3, 2007. http://www.theses.fr/2007AIX30060.
Coherent anti-Stokes Raman scattering ("CARS") is a spectroscopic technique that gives access to intra-molecular vibrational information. It was first proposed as a contrast mechanism in microscopy in 1982, and was implemented under a convenient colinear configuration in 1999. Since then, the signal generation in CARS microscopy has been studied in the litterature on some simple configurations. In this PhD dissertation, we extend the CARS signal generation study in isotropic media using a full-vectorial formalism. In particular, we introduce CARS signal dependency on the Raman depolarisation ratio and study theoretically its influence on far-field radiation patterns. In another part, we investigate the CARS signal generation in the vicinity of transverse and axial interfaces. On the one hand, a very simple method to obtain background free CARS spectra (i. E. Similar to pure Raman spectra) near transverse interfaces, with conventional excitation, is presented. One the other hand, we show theoretically and experimentally how the excitation detuning modifies the contrast of axial interfaces. These effects are tightly bound to the coherent and resonant nature of CARS. Finally, in order to enhance CARS microscopy sensitivity, we propose to generate the CARS signal near a resonant structure. In this purpose, we lead theoretical and experimental studies of CARS signal generation in a Fabry-Perot cavity. We show how this cavity enhances signal, increases its directivity and symetrise Fwd-CARS and Epi-CARS signals. Such effects are interesting for CARS microscopy. This last study illustrates the electromagnetic environment influence on light emission
El, Merhubi Hilal. "Application de diagnostics spectroscopiques pour la mesure d’espèces clés impliquées dans la formation du NO précoce dans des flammes de prémélange à basse pression". Thesis, Lille 1, 2013. http://www.theses.fr/2013LIL10131/document.
Since the work of theoretical chemistry by Moskaleva and Lin (2000), it is known that the NCN radical is the product of the initiation reaction CH + N2 of prompt NO in flames. Under the ANR NO-mecha program, the objective of this thesis was to extend in different flames stabilized at low pressure (5.3 kPa), the initial experimental database (including CH and NCN profiles) to the species NO, HCN and CN involved in the prompt NO formation in order to validate a kinetic mechanism. In this work, measurements of mole fractions were measured in situ (for labile species) and ex situ (HCN) by combining two methods of laser spectroscopy. The laser induced fluorescence (LIF) is used to measure profiles of species directly in the flame. This technique is used to measure the temperature from the rotational population distribution of NO. The LIF measurements are calibrated by a method of standard additions (NO) or by absorption (CN). The adopted absorption technique is the Cavity Ringdown Spectroscopy (CRDS) based on the measurement of the lifetime of a laser pulse in an optical cavity. Measurement of HCN profile was carried out using an original method after gas extraction to an external CRDS cell at 1036 nm. The studies focused on five premixed flames of CH4/O2/N2 (richness comprised between 0.8 and 1.25) with a doped flame by N2O. The experimental results are compared with the kinetic simulation using the Chemkin/Premix code and the GDFkin®3.0_NCN mechanism, showing an overall satisfactory agreement
Grenouillet, Laurent. "Spectroscopie optique de nouveaux matériaux à base de (Ga,In)(N,As) pour la réalisation de composants à cavité verticale émettant à 1,3 µm sur substrat GaAs". Lyon, INSA, 2001. http://theses.insa-lyon.fr/publication/2001ISAL0055/these.pdf.
In this work, the optical properties of the GaNAs and GaInNAs narrow band gap nitride materials are investigated. Recently, these III-V semiconductor alloys with a low fraction of nitrogen (around 2%) have been successfully used to grow optoelectronic devices emitting in the 1. 3 micro-m – 1. 55 micro-m wavelength range on GaAs substrates. Therefore the transmission window of silica fibers become accessible to the GaAs-based devices with these III-V-N compounds. Photoluminescence and photoreflectance are first used to optimizee Ga(In)Nas growth conditions. The giant bowing parameter of the alloy, i. E. The drastic decrease in the band gap energy with nitrogen incorporation, is also described and explained. It is then used to achieved 1. 3 micro – m emission at room temperature with GaInNAs/GaAs quantum wells. Optical spectroscopy in the 8 K – 300 K temperature range shows an anormalous behavior of the photoluminescence spectrum temperature dependence. This indicates that excitons are strongly localized at low temperature, and progressively delocalised as temperature increases, changing the nature of radiative recombinations from localized to delocalized. Finally, it is shown that these alloys are very sensitive to rapid thermal annealing. Post-growth annealing indeed increases the radiative efficiencies, but also induces a blue shift of the emission spectra, and a decrease in the localization effects. Based on experimental results, an original explanation of this blue shift is proposed, and a simple model is developed to account for the observed phenomena. All these results contribute to a better understanding of the mechanisms for the photoluminescence of narrow band gap nitrides and its evolution as thermal annealing proceeds. It should help to improve the optical properties of optoelectronic devices
Assaf, Emmanuel. "Kinetic study of reactions with interest to atmospheric chemistry by simultaneous detection of OH and RO2 radicals coupled to laser photolysis". Thesis, Lille 1, 2017. http://www.theses.fr/2017LIL10095/document.
The hydroxyl radical OH and hydroperoxy radical HO2 radicals are key species in many oxidation processes in the atmosphere. The degradation of volatile organic compounds under tropospheric conditions is induced by reactions with hydroxyl radicals followed by the subsequent chemistry of the initial OH oxidation products with O2. This thesis was focused on the kinetic study of some of these atmospherically relevant reactions to better understand their oxidation mechanisms using an experimental system of laser photolysis coupled to Laser Induced Fluorescence (LIF, for OH radical) and continuous-wave Cavity Ring-Down Spectroscopy (cw-CRDS, for OH, HO2 and RO2 radicals) detection techniques. After determining the infrared spectrum of OH, HO2 and CH3O2 radicals in the near infrared region and the absorption cross-sections of few selected lines, four systems were studied with the above mentioned techniques: CH3O2 + OH, C2H5O2 + OH, C3H7O2 + OH and C4H9O2 + OH. The rate constant and the HO2 yield of the four reactions were determined. In addition, the rate constants of few secondary reactions such as CH3O + HO2, CH3O + CH3O or OH + HO2 have been determined
Pongráczné, Faragó Eszter. "Combined experimental and theoretical investigation of the reactivity of CH3O2 and C2H5O2". Thesis, Lille 1, 2015. http://www.theses.fr/2015LIL10159/document.
Peroxy radicals are key intermediates in atmospheric chemistry. Their reaction schemas are different depending if they are formed in a polluted environment (high NOx concentration) or in a clean environment (low NOx concentration). This thesis deals with the reaction between peroxy radicals and OH radicals in order to better understand the reaction scheme in clean environments (above the oceans or tropical forest). Kinetic studies were carried out using laser photolysis coupled to detection of radical species by laser induced fluorescence technique (LIF, for OH), and continuous wave- cavity ring-down spectroscopy (cw-CRDS, for peroxy radicals). Moreover, the reaction mechanisms of these reactions were determined by quantum chemical methods, such as Gaussian-4 (G4), complete basis set model (CBS) and CHEAT1. Two systems were studied with the above mentioned techniques: CH3O2 + OH and C2H5O2 + OH. The rate constant and reaction mechanism of both reactions were determined for the first time. In addition, the cw-CRDS technique was applied to measure the absorption spectrum of the CH3O2 and CH3I in the near infrared region and to determine the absorption cross sections of a few selected lines of the methyl peroxy radical. Furthermore, a method test was carried out, which ensured the appropriate quantum chemical method for these radical-radical reactions
Burkart, Johannes. "Optical feedback frequency-stabilized cavity ring-down spectroscopy - Highly coherent near-infrared laser sources and metrological applications in molecular absorption spectroscopy". Thesis, Université Grenoble Alpes (ComUE), 2015. http://www.theses.fr/2015GREAY045/document.
High-precision molecular absorption spectroscopy is a powerful tool for fundamental physics and metrology, as well as for a broad range of applications in fields such as environmental sciences, planetology and astrophysics. In recent years, spectroscopic techniques based on the enhanced interaction of laser light with molecular samples in high-finesse optical cavities have provided outstanding detection sensitivities on the absorption axis, while the spectrometer frequency axis rarely met as high precision standards.In this thesis, we addressed this challenge by the development of Optical Feedback Frequency-Stabilized Cavity Ring-Down Spectroscopy (OFFS-CRDS). This novel technique features a unique combination of sub-kHz frequency resolution and stability, kW/cm^2-level intracavity light intensity, a shot-noise limited absorption detectivity down to 2 x 10^(−13) cm^(−1)Hz^(-1/2), as well as a detection limit of 8.4 x 10^(−14) cm^(−1) on a narrow spectral interval. This unprecedented performance is based on the tight Pound-Drever-Hall lock of the ring-down cavity to a single-sideband-tuned distributed-feedback diode laser which is optical-feedback-stabilized to a highly stable V-shaped reference cavity. To transfer the coherence of this sub-kHz laser source to noisier lasers in other spectral regions through an optical frequency comb, we have explored a novel high-bandwidth feed-forward phase cloning scheme and demonstrated a residual phase error as low as 113 mrad. Applying OFFS-CRDS to the spectroscopy of CO_2 near 1.6 μm, we obtained a broadband spectrum with a dynamic range of 8 x 10^5 and retrieved twelve absolute transition frequencies with kHz-accuracy by measuring sub-Doppler saturated absorption Lamb dips with a comb-assisted setup. Furthermore, we have performed a comprehensive analysis of systematic error sources in CRDS and derived an analytic formula for the non-exponential ring-down signal in a weakly saturated regime, which may contribute towards future concentration-independent transition dipole moment measurements. Our results open up promising perspectives for metrological applications of OFFS-CRDS, such as advanced absorption lineshape studies, isotopic ratio measurements and extensive saturated absorption spectroscopy in the near infrared
Louvion, Nicolas. "Microscopie en champ proche optique de structures à base de cristaux photoniques". Ecully, Ecole centrale de Lyon, 2005. http://bibli.ec-lyon.fr/exl-doc/nlouvion.pdf.
Active photonic crystals microcavities have been studied by NSOM measurements. Those structures have been studied by spacialy and spectrally resolved near infrared photoluminescence spectroscopy. The NSOM probe is an non metallised chemically etched optical fiber, with a diameter of 250 nm, used in collection mode. This device allow us to study several photonic crystal based-on structures, especially H1 an H2 in microcavities, in near field
Zumsteg, Cedric. "Spectroscopie ultra haute résolution d'un ion unique de calcium". Phd thesis, Université de Provence - Aix-Marseille I, 2010. http://tel.archives-ouvertes.fr/tel-00507487.
Derom, Stephane. "Plasmonic cavities and optical nanosources". Thesis, Dijon, 2013. http://www.theses.fr/2013DIJOS060/document.
Optical microcavities exhibit high resonance quality, so that, they are of key interest for the design of low-threshold lasers or for achieving strong coupling regime. But, such systems support modes whose the volume remain diffraction limited.In this manuscript, we are interested in their plasmonic counterparts because they support confined modes at the sub-wavelength scale. First, we study an in-plane plasmonic cavity which is the transposition of 1D optical cavity to surface wave. We characterize the cavity by measuring the fluorescence lifetime of dye molecules deposited inside.Then, we are interested in 3-dimension mode confinement achieved by spherical metal nanoparticles. We discuss on the definition of the mode volume used in cavity quantum electrodynamic and based on the calculation of energy confinement around the particle. We also simulate the fluorescence enhancement of rare-earth ions embedded inside core-shell plasmonic particles. Finally, we disturb the photodynamic emission of a single-photon source by puttingthe extremity of a plasmonic tip nearby the emitter
Motto-Ros, Vincent. "Cavités de haute finesse pour la spectroscopie d'absorption haute sensibilité et haute précision : Application à l'étude de molécules d'intérêt atmosphérique". Phd thesis, Université Claude Bernard - Lyon I, 2005. http://tel.archives-ouvertes.fr/tel-00011763.
Tout d'abord, la technique CW-CRDS (Continuous Wave – Cavity Ring Down Spectroscopie) est utilisée pour étudier l'évolution avec la pression et la température des spectres atmosphériques de la vapeur d'eau dans le proche infrarouge. Cette étude, destinée à calibrer des mesures d'absorption différentielle par Lidar, entre dans le cadre de la mission WALES (Water Vapour Lidar Experiment in Space) proposée par l'Agence Spatiale Européenne. Une attention particulière est portée pour décrire et caractériser le système expérimental.
Ensuite, la technique OF-CEAS (Optical Feedback Cavity Enhanced Absorption Spectroscopy) et ses performances pour la spectroscopie sont mises en évidence avec l'étude de la bande B de l'oxygène dans le rouge. Cette technique repose sur un schéma d'injection avec rétroaction optique (de la cavité vers le laser) qui permet d'augmenter la cohérence de son émission pour mesurer les maxima de transmission des modes même avec des cavités de haute finesse. Une configuration nouvelle permettant ces effets est proposée (la cavité Brewster). Une gamme dynamique sur la mesure d'absorption d'environ cinq ordres de grandeurs est démontrée (1e-5 à 1e-10 /cm) ainsi qu'une sensibilité < 1e-10 /cm/Hz^(1/2). Un schéma d'acquisition mode par mode est employé et permet d'exploiter la linéarité du peigne de mode pour atteindre des hautes précisions sur la fréquence. La pertinence de cette approche est mise en évidence par la mesure de « pressure shifts » de l'oxygène obtenus avec une précision absolue record inférieure à 5*1e-5 cm^(-1)/atm.
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.
The 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
Richard, Lucile. "Développements de spectromètres ultrasensibles pour l'analyse de gaz par « optical feedback cavity enhanced absorption spectrocopy » dans le moyen infrarouge avec des lasers à cascades inter-bandes". Thesis, Université Grenoble Alpes (ComUE), 2019. http://www.theses.fr/2019GREAY004/document.
This work of these has made it possible to develop and characterize the use of instruments on the "OF-CEAS" technique in the mid-infrared for traces' detection in different mixtures in the gas phase. Inter-band Cascade Laser (ICL) is the latest innovation in semiconductor lasers in this spectral region. Compatibility of ICL with OF-CEAS offers new applications for compact and robust instruments with fast response time and a low detection limit. A demonstration of the good sensitivity and stability of the OF-CEAS instruments was performed with continua absorption measurements (water vapor and nitrogen). But also with the detection of a very low intensity quadrupole line of nitrogen (3x10-29 cm-1/(moléc cm-2). The main objective of this work was to develop an instrument dedicated to nitrogen oxide detection for the analysis of exhaled breath. The analyzer is presented at the sensitivity of 6x10-10 cm-1 in an acquisition of 180 ms. Its limit of detection on NO is at the state of the art, with short term (180 ms) limit of 50 ppt. It reaches the sub-ppt level (0.9 ppt) with 12 min of integration
El, Merhubi Hilal. "Application de diagnostics spectroscopiques pour la mesure d’espèces clés impliquées dans la formation du NO précoce dans des flammes de prémélange à basse pression". Electronic Thesis or Diss., Lille 1, 2013. http://www.theses.fr/2013LIL10131.
Since the work of theoretical chemistry by Moskaleva and Lin (2000), it is known that the NCN radical is the product of the initiation reaction CH + N2 of prompt NO in flames. Under the ANR NO-mecha program, the objective of this thesis was to extend in different flames stabilized at low pressure (5.3 kPa), the initial experimental database (including CH and NCN profiles) to the species NO, HCN and CN involved in the prompt NO formation in order to validate a kinetic mechanism. In this work, measurements of mole fractions were measured in situ (for labile species) and ex situ (HCN) by combining two methods of laser spectroscopy. The laser induced fluorescence (LIF) is used to measure profiles of species directly in the flame. This technique is used to measure the temperature from the rotational population distribution of NO. The LIF measurements are calibrated by a method of standard additions (NO) or by absorption (CN). The adopted absorption technique is the Cavity Ringdown Spectroscopy (CRDS) based on the measurement of the lifetime of a laser pulse in an optical cavity. Measurement of HCN profile was carried out using an original method after gas extraction to an external CRDS cell at 1036 nm. The studies focused on five premixed flames of CH4/O2/N2 (richness comprised between 0.8 and 1.25) with a doped flame by N2O. The experimental results are compared with the kinetic simulation using the Chemkin/Premix code and the GDFkin®3.0_NCN mechanism, showing an overall satisfactory agreement
Reserbat-Plantey, Antoine. "Nanosystèmes graphitiques : cavités optiques ajustables et détection spectrale des contraintes dans un nanorésonateur mécanique". Phd thesis, Université de Grenoble, 2012. http://tel.archives-ouvertes.fr/tel-00767927.
Betrancourt, Christopher. "Experimental study of soot formation in laminar premixed flames of fuels of interest for automobile and aeronautics : a focus on the soot nucleation process". Thesis, Lille 1, 2017. http://www.theses.fr/2017LIL10203/document.
Emission of soot formed from incomplete combustion of fossil fuels, biofuels and biomass is a serious concern due to soot’s harmful impact on human health, environment and its radiative forcing on climate. Gaining fundamental understanding of soot formation, particularly the nucleation step leading to the formation of the nascent soot particles, is critical to develop reliable predictive soot models and to help the design of more efficient and cleaner combustion devices. This work demonstrates that nascent soot particles in the size range of 2-4 nm are able to emit a black body radiation by combined Laser Induced Incandescence (LII), scanning mobility particle sizer (SMPS) and helium-ion microscopy (HIM). These nascent soot particles are investigated in nucleation premixed flames in which soot particles are essentially formed by nucleation, without growth by soot surface processes and in standard sooting premixed flames in which growth processes occur. This work provides an extensive database for improvement of kinetics modelling of sooting flames with a focus on the soot nucleation in flames. Two kinds of fuels have been selected: n-butane and mixture of n-butane and n-propylbenzene. For each fuels two flames have been studied: a nucleation and a standard sooting flames. The database consist of species profiles obtained by online gas chromatography, temperature profiles measured by Laser induced fluorescence thermometry, soot volume fraction profiles obtained by LII calibrated by cavity ring-down extinction and particles size distributions obtained in n-butane flames by SMPS and HIM. From this database effect of equivalence ratio and fuel composition is analyzed
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". Phd thesis, Université de Grenoble, 2012. http://tel.archives-ouvertes.fr/tel-00849145.
Courtois, Jérémie. "Développements de systèmes multipassages pour application à la spectroscopie d'absorption : Cavity Ring Down Spectroscopy multimode et cellules à passages multiples". Phd thesis, Université Paris Sud - Paris XI, 2009. http://tel.archives-ouvertes.fr/tel-00458101.
Pillier, Laure. "Formation de monoxyde d'azote dans des flammes prémélangées CH4/C2H6/C3H8/O2/N2 : étude expérimentale par diagnostics laser et modélisation". Lille 1, 2003. https://pepite-depot.univ-lille.fr/LIBRE/Th_Num/2003/50376-2003-365.pdf.
Bouvier, Yoann. "Caractérisation de suies et de précurseurs de suies dans des flammes par incandescence induite par laser". Lille 1, 2006. https://pepite-depot.univ-lille.fr/LIBRE/Th_Num/2006/50376-2006-Bouvier.pdf.
Cette étude a été effectuée de manière originale en utilisant un profil de faisceau laser gaussien et en comparant la détection "classique" à angle droit à la détection dans le sens contraire à la propagation du faisceau (rétro-LII) Cette comparaison a permis de valider un dispositif de mesure de fraction volumique de suies par rétro-LII à l'échappement des moteurs. Une méthode expérimentale de détermination de révolution de la fonction d'indice de réfraction E(m) avec la longueur d'onde est proposée par comparaison des signaux LII obtenus en utilisant des longueurs d'onde d'excitation dc 532 nm et 1064 nm. Une validation de la méthode est effectuée par comparaison avec des mesures d'extinction obtenues par mesure du temps de déclin d'une cavité optique (CRDS) aux mêmes longueurs d'onde. La structure des flammes "jet" supports a été étudiée par couplage de l'Incandescence Induite par Laser des suies et de la Fluorescence Induite par Laser des HAP à 532 nm (LII / LIF). La calibration des fractions volumiques de suies est effectuée par mesure du temps de vie d'une cavité optique à 1064 nm. Des cartographies suies / HAP sont ainsi obtenues dans une flamme de diffusion de méthane et dans les deux flammes de prémélange. La sensibilité des techniques mises en œuvre permet de détecter de très faibles teneurs en suies (< 1 ppb). Une méthode novatrice de mesure de la vitesse des particules de suie dans les flammes est également proposée
Lelaidier, Tony. "Organic semiconductor characterisation by scanning tunnelling microscopy and optical spectroscopy". Thesis, Aix-Marseille, 2016. http://www.theses.fr/2016AIXM4032/document.
Electronic and self-assembling properties of two organic compound, the DHTAP and the bis-pyrene, have been studied by the means of low temperature scanning tunnelling microscopy (STM) under ultrahigh vacuum conditions. Optical properties have been studied by cavity ring-down (CRD) spectroscopy, also under ultrahigh vacuum conditions.The growth of DHTAP has been studied on different metallic substrate. The growth of bis-pyrene has been studied on Au(111). In each case, the optimal temperature conditions for the formation of a well-ordered first monolayer have been determined. The formation of second monolayers has also been studied. The evolution of the optical properties, studied by CRD, of bis-pyrene deposited on borosilicate glass combined with information obtained from STM allow us to identify these modifications as interactions between transition dipole moments of molecules in the first and in the second layer, and also determine the growth mode.Finally, the possibility to induce chemical modification of DHTAP molecules embedded in an ordered monolayer using the tunnelling current of the STM has been studied. It appears that the molecule embedded in the first ML can be doubly dehydrogenated which leads to the formation of a compound identified as 5,7,12,14-tetraazapentacene (TAP). In the second layer, the formation of two radicals in addition to the TAP has been observed. The TAP molecule is interesting because of that it cannot be synthesized using common organic chemical methods
Doutre, Florent. "Sources d'impulsions brèves basées sur des procédés de découpe non linéaires au sein d'une fibre optique ; nouvelles sources déclenchées à cavités couplées". Phd thesis, Université de Limoges, 2010. http://tel.archives-ouvertes.fr/tel-00682880.
Kravtchenko, Florent. "Développement et validation d’un nouveau dispositif expérimental pour l’étude des réactions RO2 + HOx". Thesis, Lille 1, 2019. http://www.theses.fr/2019LIL1R067.
In the atmosphere, the degradation of organic pollutants such as Volatile Organic Compounds (VOCs) is induced by the most important atmospheric oxidant: the hydroxyl radical OH. This degradation leads to the formation of peroxy radicals: hydroperoxy HO2 and alkylperoxy RO2. These radicals play a major role in tropospheric chemistry. The reactivity of RO2 and HOX (HO2 and OH) radicals controls the oxidative capacity of the atmosphere and the formation of tropospheric ozone and secondary pollutants. In remote environments (or “clean environment” such as tropical forests or marine boundary layer), where the concentration of nitrogen oxides (NOx) is low, the reactions between RO2 and HOx dominate the atmospheric chemistry. However, this chemistry is still poorly known and controversial in the literature. The uncertainties and/or lack of data on RO2+HOx reactions rates and branching ratios can lead to important errors on modelling of ozone and radical concentrations in the atmosphere. The aim of the present work is the development of a new and innovative experimental device to bring new experimental results for the reactions RO2 + HOx. The new setup consists of a fast flow tube coupled to three complementary techniques: Laser Induced Fluorescence (LIF) for OH radical measurements, continuous wave Cavity Ring-Down Spectroscopy (cw-CRDS) for HO2 radical measurements and Mass Spectrometry with Molecular Beam sampling (MB/MS) for measurement of stable reaction products and radical species. First, each of the three techniques has been validated independently, and then the validation of the complete system was done through the study of different known reactions between a stable species (ethane, propane, methanol, CO) and OH radicals. Two methods of OH radicals generation in the reactor were used: through the reaction F+H2OOH+HF and the reaction H+NO2OH+NO. An unexplained OH recycling phenomenon in the reactor has been observed for all reaction partners (except CO) when using F+H2O as precursors. This was confirmed during the study of reactions involving the same deuterated species. In this manuscript, the different tests that have been carried out in order to understand this phenomenon are described
Doutre, Florent. "Sources d'impulsions brèves basées sur des procédés de découpe non linéaires au sein d'une fibre optique : nouvelles sources déclenchées à cavités couplées". Phd thesis, Limoges, 2010. https://aurore.unilim.fr/theses/nxfile/default/e33cc738-1c73-49a3-bc51-cc0cfd98658c/blobholder:0/2010LIMO4055.pdf.
This thesis deals with the improvement of microchip laser pulses characteristics. On one hand, we exploit the fact that pulses injected in an optical fiber experiment both nonlinear polarisation rotation and Raman scattering. A dual spectrum and polarization filtering allows a temporal cut-off permitting a tunable shortening of their duration up to a factor 16 (from 600ps to 32ps). On the second hand, a double nested cavity source including a microchip laser is Q-switched by a hybrid active/passive process. This original configuration shows a timing jitter reduced by two orders of magnitude compared to a microchip laser on its own. These techniques allow the emission of pulses with short duration, high stability, low timing jitter from miniature low-cost sources, especially attractive for remote sensing applications like flow cytometry, LIDAR or CARS spectroscopy
Assali, Mohamed. "Réactivité des radicaux peroxyles étudiée par photolyse laser couplée aux techniques cw-CRDS et LIF". Electronic Thesis or Diss., Université de Lille (2018-2021), 2021. http://www.theses.fr/2021LILUR046.
Degradation of volatile organic pollutants, such as Volatils Organic Compounds (VOCs), under tropospheric conditions is usually initiated by the main oxidant which is the OH radical, followed by the formation of hydroproxy radicals HO2 and alkylperoxy radicals RO2 by reaction of products with oxygen. The fate of these radicals plays an important role in tropospheric chemistry. They are closely linked to the cycle that controls the oxidative capacity of the atmosphere and the formation of tropospheric ozone. In a polluted environment, the influence of peroxy radicals is well known and many experimental results are available in the literature. In a clean environment (with low nitrogen oxides NOx (x=1,2) concentration) the reactivity between HOx (x=1,2) and RO2 controls tropospheric chemistry. However, this chemistry is not yet well known. In the frame of this thesis, experimental kinetic studies have been carried out to better understand the oxidation mechanisms of these species. An experimental laser photolysis device coupled with time-resolved spectroscopic detection techniques: continuous wave Cavity Ring-Down Spectroscopy (cw-CRDS) allowing the detection of HO2 and RO2 radicals and Laser Induced Fluorescence (LIF) for the detection of OH radicals was used.Different reaction systems were studied using the experimental technique mentioned above:1) the reaction of CH3C(O)O2 + CH3C(O)O2, and CH3C(O)O2 + CH3O2, 2) CH3C(O)CH2O2 + CH3C(O)CH2O2 and for the first time the reaction Cl + CH3C(O)CH2O2, 3) DO2 + DO2 and for the first time the reaction HO2 + DO2. The rate constants were determined for these six reactions at ambient temperature. For the first four different reaction pathways are possible, and we have also determined the branching ratio of the pathway leading to the formation of radicals for these reactions
Simon, Eric. "Vers une stabilité et une exactitude de 10-16 pour les horloges atomiques : - le rayonnement du corps noir - la détection optique". Phd thesis, Université Paris Sud - Paris XI, 1997. http://tel.archives-ouvertes.fr/tel-00639420.
Crunaire, Sabine. "Développement d'un spectromètre cw-CRDS et son application à l'étude de mécanismes de réaction en chambre de simulation atmosphérique". Lille 1, 2005. https://pepite-depot.univ-lille.fr/LIBRE/Th_Num/2005/50376-2005-Crunaire.pdf.
Les tests de validation et de caractérisation efféctués ont démontré une grande sensibilité, une vitesse d'acquisition élevée et des limites de détection basses pour des composés tels que l'acétylène ou le dioxyde de carbone, ou encore des composés isotopiques (RDO, H2180, etc. ). Les premières expériences menées en chambre de simulation atmosphérique au moyen de ce couplage analytique innovant, ont été dédiées à la détermination de la distribution des produits de la réaction entre les radicaux OH et l'acide acétique, CH3C(O)OH. Au cours de ce travail de thèse, la détermination du rapport de branchement de la voie d'arrachement de l'atome d'hydrogène du groupement carboxylique a fait l'objet d'une première détermination à température ambiante et à pression atmosphérique, en détectant le CO2 formé au cours de la réaction. De plus, la caractérisation des produits stables formés par le second chemin réactionnel a fait l'objet d'une investigation par analyse en chromatographie ionique. Enfin, pour une meilleure compréhension de ce mécanisme d'oxydation, des expériences complémentaires utilisant un isotopomère de l'acide acétique: CH3C(O)OD ont été menées
Paquet, Alex. "Biodétection au moyen des modes de galerie de microsphères fluorescentes". Thesis, Université Laval, 2011. http://www.theses.ulaval.ca/2011/28672/28672.pdf.
Szriftgiser, Pascal. "Cavité gravitationnelle et optique atomique temporelle". Phd thesis, Université Pierre et Marie Curie - Paris VI, 1996. http://tel.archives-ouvertes.fr/tel-00011912.
Garnache, Arnaud. "Etude et réalisation de nouveaux types de lasers proche infrarouge pour la spectroscopie d'absorption intracavité laser : dynamique des lasers fortement multimodes". Université Joseph Fourier (Grenoble), 1999. http://www.theses.fr/1999GRE10256.
Shamas, Mirna. "Study of the reactivity of radical species of peroxyl type of atmospheric interest". Electronic Thesis or Diss., Université de Lille (2022-....), 2022. http://www.theses.fr/2022ULILR036.
In the atmosphere, organic pollutants such as Volatile Organic Compounds (VOCs) from biogenic or anthropogenic sources are oxidized by OH radicals leading to the formation of peroxy radicals RO2 and HO2, which play a major role in tropospheric chemistry. Their reactivity controls the oxidative capacity of the atmosphere (cycling of reactive radicals) and the formation of tropospheric ozone and other secondary pollutants. While the reactivity of these peroxy radicals is well known in polluted environments (high NOX concentrations), it is still poorly known in a remote environments containing low concentrations of NOx (ex: tropical forests, marine boundary layer).The aim of the present work is to study the kinetics of some of these peroxy radicals to better understand the radical + radical reactions in clean atmosphere. Two experimental set-ups have been used. First a fast discharge flow reactor, originally designed to complement an existing photolysis cell set-up, was continued to be developed in the frame of this work. This fast flow reactor is coupled to three complementary techniques: the continuous-wave Cavity Ring-Down Spectroscopy (cw-CRDS) for the measurement of the HO2 radical, the Laser Induced Fluorescence (LIF) for the detection of the OH radical and Mass spectrometry with Molecular Beam sampling (MB/MS) for the measurement of stable reaction products and radical species. An unexplained OH reformation phenomenon has been observed in the previous work done during the validation of this recently developed experimental set-up. In this work, different tests were carried out to explain this OH reformation phenomenon and will be described here. Meanwhile a laser photolysis cell coupled to a double cw-CRDS paths for the simultaneous measurements of RO2 and HO2 radicals was used to determine the absorption cross-section of C2H5O2 radical, the rate constant of C2H5O2 + HO2, and the rate constant and branching ratios for the C2H5O2 self-reaction
Sebastian, Ananthu. "Noise dynamics in multi-Stokes Brillouin laser". Thesis, Rennes 1, 2020. http://www.theses.fr/2020REN1S068.
Stimulated 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
Doumbia, Yaya. "Optical injection dynamics and polarization properties of semiconductor lasers frequency combs". Electronic Thesis or Diss., CentraleSupélec, 2021. http://www.theses.fr/2021CSUP0008.
In this work, we study the nonlinear dynamics of laser diodes optically injected with frequency combs.We first theoretically and experimentally analyze the nonlinear dynamics of edge-emitting lasers (EELs) from an optical injection of frequency combs. The injection parameters and injected comb properties are varied to unveil several locked and unlocked dynamics. For large enough injection strength and over a large detuning range, the injection locking bifurcates to a time-periodic dynamics corresponding to an optical frequency comb that extends the injected comb to a much broader optical spectrum. A bifurcation analysis reveals a cascade harmonic frequency comb dynamics leading to a significant increase in the output comb lines. We have also used the injection parameters, comb properties, and injection current to control the new comb properties. We secondly analyze the nonlinear dynamics and polarization properties in vertical-cavity surface-emitting lasers (VCSELs) subject to orthogonal optical injection with frequency combs experimentally. Most importantly, the VCSEL shows two frequency combs with orthogonal polarization from a single device for some injection parameters. We also demonstrate the possibility to control the single or two polarizations comb repetition rate through harmonic frequency combs generation. We finally present experimentally and theoretically the VCSEL injection dynamics from parallel optical frequency comb injection. We show that the two polarizations combperformance is restricted to high current injection in the case of parallel optical injection. For fixed bias current, the two polarization comb dynamics disappear when increasing the injected comb spacing.This thesis therefore demonstrates besides its interest for nonlinear laser dynamics, optical injection is a technique to harness the comb properties in laser diodes
Morin, Drouin Étienne. "Réduction du bruit optique dans un oscillateur paramétrique optique par l'ajout d'une cavité externe". Thesis, Université Laval, 2007. http://www.theses.ulaval.ca/2007/24229/24229.pdf.
Drouin, Étienne M. "Réduction du bruit optique dans un oscillateur paramétrique optique par l'ajout d'une cavité externe". Master's thesis, Université Laval, 2007. http://hdl.handle.net/20.500.11794/18769.
Monterrat, Eric. "Spectroscopie optique d'hétérostructures CdHgTe/CdTe". Grenoble 1, 1992. http://www.theses.fr/1992GRE10160.
Marotel, Pascal. "Spectroscopie optique de l'oxyde de zinc". Phd thesis, Université de Grenoble, 2011. http://tel.archives-ouvertes.fr/tel-00647305.