Analytical model of optical field distribution of thin disk laser with thermal-optical aberration gain medium

•An analytical model about field distribution of thin disk laser is proposed.•The uniform pumping spot will decrease aberration and improve the beam quality.•The spherical part of OPD could not cause decreasing of the beam quality.•The degradation of beam quality is only Caused by Asperical part of OPD.

An analytical model is developed to analyze the optical field distribution of thin disk laser with a thermal-optical aberration gain medium. The fundamental mode field distribution is calculated by using the eigenvector method of the resonator transit matrix for different pumping parameters. The analytical results show that the uniformity of the pumping spot is an important factor that impacts the beam quality of thin disk laser. The uniform pumping spot is beneficial to decrease thermal aberration and Optical Path Difference (OPD) of thin disk crystal, and to improve the beam quality. However, the beam quality still decreases slightly with the increasing of pumping intensity under the uniform pumping condition. The main reason for degradation of beam quality is the aspherical part of OPD which leads to diffraction losses of the resonator and wavefront deformation.