Improvement on evaluating absorption efficiency of a medium rod for LD side-pumped solid-state lasers

In order to comprehensively evaluate the absorption efficiency of the Nd:YAG rod for a LD side-pumped laser, a mathematical process is proposed to analyze the optical feature inside an open chamber where the specular reflection takes place at the internal wall of the reflector. The scheme is named as finite recurring approach (FRA) in which the ray trace and the computer extrapolation were undertaken during the evaluation. The absorption efficiency for an actual LD side-pumped solid-state laser is thought to be between the results of FRA and the infinite convergence approach (ICA), which is used to calculate the absorption efficiency when the random diffuse reflection occurring on the inner surface of the reflector wall. The experiment results distinctly sustained the theoretical inference and demonstrated that the absorption efficiency of a reflecting chamber can be improved by optimizing the reflector geometry. The proposed mathematic model is also appropriate to be used in the other schemes of LD side-pumped solid-state lasers where the geometrical structures are different from that specified in this study.