L’Institut Foton vous convie à la présentation des travaux de thèse de doctorat :
Peignes de fréquences à diversité de polarisation dans les lasers à solides dopés ytterbium
Gaedze Kudjo HERMAN AKAGLA
sous la direction de Marc BRUNEL
La soutenance aura lieu le jeudi 17 octobre à 9h30 en salle des thèses, Bât. 1, Campus de Beaulieu.
Title: Polarization diversity frequency combs in ytterbium-doped solid-state lasers
Keywords: Ytterbium, dual-frequency laser, polarization, dual-comb
Abstract: Ytterbium lasers are widely used for short pulse generation, in particular for dual- comb spectroscopy. In this thesis work, we ex- perimentally developed specific laser architec- tures for ytterbium-doped solid-state lasers, such as: Yb:YAG, Yb:Lu:YAG, Yb:Na:CNGG and Yb:CaF2. In these quasi-isotropic active media, two eigenstates with orthogonal polar- izations can oscillate simultaneously, generat- ing two pulse trains that can be synchronous or asynchronous, depending on the type of cavity architecture. We first show that the orientation of the pump polarization is an ef- fective tool of power control in bipolarized ytterbium lasers. The experimental results ob- tained are then compared with a two-mode rate-equation model taking into account the pump-induced gain anisotropy and the cross- saturation in the active medium. Secondly, we experimentally demonstrate a dual fre- quency comb with synchronous pulse trains in Yb:YAG and Yb:Lu:YAG bipolarized passive mode-locked lasers containing two intracavity quarter-wave plates. Finally, the achievement of an asynchronous dual-frequency comb in the Yb:YAG laser, as well as the tunability of the repetition rates, has been demonstrated.