Computer simulation of thermal focal length of laser crystal and thermally-near-unstable resonator

Abstract

A simple method determining the thermal focal length of gain medium was investigated. Then by using computer simulation results, a novel configuration was proposed. In the new configuration, the gain medium acts as a mode limiter at maximal pump power, which restrains resonance of high-order modes and guarantees not only high output power but also high beam quality. An LD side-pumped Nd:YAG laser with output power of 400W at 1064nm was obtained experimentally with the new configuration. The experimental results are in agreement with theoretical predictions.