Modeling of the 3D spatio-temporal thermal profile of joule-class -based laser amplifiers

摘要： Thermal pro?le modi?cation of an active material in a laser ampli?er via optical pumping results in a change in the material’s refractive index, and causes thermal expansion and stress, eventually leading to spatial phase aberrations, or even permanent material damage. For this purpose, knowledge of the 3D spatio-temporal thermal pro?le, which can currently only be retrieved via numerical simulations, is critical for joule-class laser ampli?ers to reveal potentially dangerous thermal features within the pumped active materials. In this investigation, a detailed, spatio-temporal numerical simulation was constructed and tested for accuracy against surface thermal measurements of various end-pumped Yb3+-doped laser-active materials. The measurements and simulations show an excellent agreement and the model was successfully applied to a joule-class Yb3+-based ampli?er currently operating in the POLARIS laser system at the Friedrich-Schiller-University and Helmholtz-Institute Jena in Germany.