Linear polarization output performance of Nd:YAG laser at 946 nm considering the energy-transfer upconversion**Project supported by the National Key R&D Program of China (Grant No. 2016YFA0301401) and the Fund for Shanxi “331 Project” Key Subjects Construction, China (Grant No. 1331KS).

Abstract

A theoretical model of quasi-three-level laser system is developed, in which both the thermally induced depolarization loss and the effect of energy-transfer upconversion are taken into account. Based on the theoretical investigation of the influences of output transmission and incident pump power on thermally induced depolarization loss, the output performance of 946 nm linearly polarized Nd:YAG laser is experimentally studied. By optimizing the transmission of output coupler, a 946 nm linearly polarized continuous-wave single-transverse-mode laser with an output power of 4.2 W and an optical–optical conversion efficiency of 16.8% is obtained, and the measured beam quality factors are and . The theoretical prediction is in good agreement with the experimental result.