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Étude théorique et expérimentale de la génération et de la mise en forme d'impulsions térahertz

Abstract : This thesis deals with the theoretical and experimental study of the generation and shaping of terahertz (THz) pulses. At first, we have studied the generation of THz pulses by optical rectification of intense femtosecond laser pulses in semiconductor ZnTe crystals. We have demonstrated a strong dependence of the efficiency of the generation process with the intensity of the laser pulse. This is reflected particularly by a progressive shift of the spectrum towards lower frequencies and an abnormal evolution of the THz energy with laser intensity. These behaviors result from a combination of three phenomena: the depletion of the laser pulse during its propagation in the crystal, the absorption of THz wave by free carriers created by two-photon absorption and a change of the phase matching condition induced by hot carriers. Secondly, we have developed an analytical approach to generate THz shaped pulses particularly interesting for coherent spectroscopy or coherent control. In particular, we have generated phase-locked THz pulses pairs, pulse trains and tunable narrow-band THz pulses. This technique is based on optical rectification of shaped femtosecond laser pulses generated by a liquid crystal Fourier filter. To demonstrate the validity of our approach, we have also developed a program giving results in very good agreement with experiment.
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https://tel.archives-ouvertes.fr/tel-00446512
Contributor : Sébastien Vidal <>
Submitted on : Tuesday, January 12, 2010 - 5:39:48 PM
Last modification on : Monday, January 22, 2018 - 11:02:02 AM
Long-term archiving on: : Thursday, October 18, 2012 - 12:20:44 PM

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  • HAL Id : tel-00446512, version 1

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Sébastien Vidal. Étude théorique et expérimentale de la génération et de la mise en forme d'impulsions térahertz. Physique Atomique [physics.atom-ph]. Université Sciences et Technologies - Bordeaux I, 2009. Français. ⟨tel-00446512⟩

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