Design And Real-Time Control Of The Opd From 20 To 200 Degrees C In A Cat'S-Eye Cavity Using Thick Slabs Of Yb3+: Yag For Athermal Amplification

We demonstrate an athermal, 100 mJ-energy class Yb3+: YAG slab-based amplifier designed to operate in the range of temperatures from 20 to 200 degrees C. The gain medium consists of an edge-pumped, thick slab with a folded laser beam-path, which is defined in a cat's eye cavity thanks to 6-12 elementary paths. Highly variable operating conditions are investigated, in a close connection with the induction of severe thermal penalties in the slab. These penalties concern the material's spectroscopic properties and the thermo-mechanical distortions, at the location of the laser faces. Looking at the shape of the optical-path-difference (OPD) along the slab, we evidence a strong dependency with the pump-dependent temperature cartography inside. This involves comprehensive fits between the measurement data and Finite Element Modeling (FEM) results. As a follow-up, by closely coupling a movable cylindrical lens along the slab, we validate the efficiency of an easy-to-implement correction process to cancel the OPD in the real time. Regardless of the operating regime, this enables fully updatable lasing conditions with reduced output beam distortions in the far field of the cavity output. (C) 2021 Optical Society of America under the terms of the OSA Open Access Publishing Agreement