Numerical Analysis of Thermal Effects in a Concept of a Cryogenically Cooled Yb: YAG Multislab 10 J/100-Hz Laser Amplifier

A thermo-optical design study of different slab geometries for a concept of a cryogenically cooled multislab amplifier operating at 10 J/ 100 Hz is presented. A finite element method (FEM) is used for 3-D analysis of heat distribution, temperature, stress, and strain. From this data, birefringence, depolarization losses, and wavefront distortion are calculated for a single pass through the amplifier consisting of four slabs. A comparison of different slab shapes shows that a squareshape geometry produces the smallest thermal gradients at the outer sides of the beam region, which results in smaller depolarization losses. Although the design with square-shape slabs is more sensitive to misalignment, our study shows better results compared to the case of circular-shape slabs.