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Microscopie "CARS" (Coherent anti-Stokes Raman scattering). Génération du signal au voisinage d'interfaces et à l'intérieur d'une cavité Fabry-Perot.

Abstract : 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 connected 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 symetrises Fwd-CARS and Epi-CARS signals. Such effects are interesting for CARS microscopy. This last study illustrates the electromagnetic environment influence on light emission.
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https://tel.archives-ouvertes.fr/tel-00258999
Contributor : David Gachet <>
Submitted on : Tuesday, February 26, 2008 - 12:08:49 PM
Last modification on : Friday, October 23, 2020 - 4:37:47 PM
Long-term archiving on: : Thursday, May 20, 2010 - 6:44:56 PM

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  • HAL Id : tel-00258999, version 1

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D. Gachet. Microscopie "CARS" (Coherent anti-Stokes Raman scattering). Génération du signal au voisinage d'interfaces et à l'intérieur d'une cavité Fabry-Perot.. Physique Atomique [physics.atom-ph]. Université de droit, d'économie et des sciences - Aix-Marseille III, 2007. Français. ⟨tel-00258999⟩

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