Heat generation in quasi-three-level Yb:YAG thin-disk lasers

Abstract

A theoretical model is established to evaluate heat generation in quasi-three-level Yb:YAG thin-disk lasers. Fluorescence heating fraction, laser heating fraction, amplified spontaneous emission (ASE) heating fraction, and non-radiative relaxation heating fraction are considered in our analysis. The dynamic process and spectral properties of ASE are analyzed by using quasi-three-level system rate equations. A numerical iterative method is used to study the dynamic behavior, the fractional thermal load, proportions of all the heating factors, and the temperature of the thin-disk laser. Dynamic heating process is clearly demonstrated. Our theoretical analysis shows that the ASE effect is critical in the total heat generation and operation of thin-disk lasers, especially for a high-power thin-disk laser.