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Source laser picoseconde à haute cadence dans l'ultraviolet

Sébastien Forget 1 
1 Laboratoire Charles Fabry de l'Institut d'Optique / Elsa
LCFIO - Laboratoire Charles Fabry de l'Institut d'Optique
Abstract : Laser source are now extensively used by the biologists in their studies. In particular, the time resolved fluorescence lifetime imaging is a powerful way to obtain quantitative information on active molecules. To use efficiently this technique, a pulsed laser source operating in the visible or ultraviolet part of the spectrum is needed : the pulse duration should stand in the picosecond range whereas the repetition rate has to be around some MHz if we want to study long lifetimes (some tens of nanoseconds). The classical pulsed lasers work in the Q-switched or in the modelocked regime : in both case, it is not straightforward to obtain short pulses at this "medium" repetition rate in a simple and compact structure : one has to built very short cavities to shorten the pulse duration of the Q-switched laser or very long cavities to decrease the repetition rate of the modelocked laser. In this work we demonstrate a 200-µm long Q-switched laser as well as a 150 m long modelocked one, each of them producing picosecond pulses at some MHz of repetition rate in the infrared (1064 nm). The saturable absorber was a semiconductor (SESAM) and the laser crystal is Nd:YVO4. We then develop a tridimentionnal multipass amplifier to increase the energy of the pulses. The original geometry of this amplifier allows optimized overlap between the pump and signal beam and leads to very efficient amplification (this structure was patented with JDS Uniphase). Finally, several non-linear stages are used to reach the UV (harmonic generation) and to obtain some tunability via optical parametric generation in a periodically poled lithium niobate crystal.
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Submitted on : Wednesday, January 21, 2004 - 6:47:04 PM
Last modification on : Saturday, June 25, 2022 - 11:14:18 AM
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  • HAL Id : tel-00004272, version 1



Sébastien Forget. Source laser picoseconde à haute cadence dans l'ultraviolet. Physique Atomique [physics.atom-ph]. Université Paris Sud - Paris XI, 2003. Français. ⟨tel-00004272⟩



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