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Combinaison cohérente d'impulsions femtoseconde - Optimisation des performances des amplificateurs fibrés ultracourts.

Florent Guichard 1, 2
Abstract : Optical fiber-based ultrafast laser sources are nowadays used in numerous scientific and industrial applications. To extend further the number of possible applications, it is essential to improve their performances in terms of pulsewidth, energy per pulse, and average power. Extensive research work has been performed over the last years on this area. The work described in this manuscript is a contribution to these research efforts, and aims at improving ultrafast fiber laser sources by using coherent combination of several femtosecond pulses.The first part is devoted to energy scaling by using passive coherent combining architectures, that do not require a feedback control loop of the relative optical phase between pulses to be combined. This idea is used both in the space (combining beams) and time (combining replicas of the pulse at different delays) domains. We demonstrate that these techniques allow energy scaling and study their limitations related to optical nonlinearities and gain saturation in the amplifiers. We also propose ways to circumvent these limitations.In the second part, we study various ways of decreasing the output pulsewidth of fiber-amplified femtosecond sources. First, we implement an active coherent combining system that performs combination of two amplified femtosecond pulses with different, shifted spectral content. This allows the synthesis of a pulse that is shorter than any of the individual pulses to be combined. Another studied approach consists in tailoring the spectrum of input pulses to precompensate the spectral gain shape of the amplifier. Finally, by using passive combining architectures described in the first part, we demonstrate energy scaling of temporal nonlinear compression setups.
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Submitted on : Friday, June 25, 2021 - 10:59:55 AM
Last modification on : Thursday, July 1, 2021 - 4:47:29 PM


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  • HAL Id : tel-03270841, version 1


Florent Guichard. Combinaison cohérente d'impulsions femtoseconde - Optimisation des performances des amplificateurs fibrés ultracourts.. Optique [physics.optics]. Université Paris Saclay (COmUE), 2016. Français. ⟨NNT : 2016SACLO001⟩. ⟨tel-03270841⟩



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