Mode characteristics analysis by using waverfront reconstruction for crystal Q-switched slab solid-state lasers

Some representative factors of intracavity perturbation will obviously degrade output power and beam mode properties for crystal passive Q-modulated solid-state lasers. In this paper, eigenmode of resonators using general asymmetric circular mirrors in solid-state lasers is briefly discussed, moreover, experiment analysis of the output beam quality on a passive Q-switched zig-zag slab Nd:YAG laser has been presented by adopting Hartmann–Shack (H–S) method and Zernike mode reconstruction theory. In this way, the PV and RMS errors of the wavefront aberration, each order Zernike aberrations can be acquired accurately, distribution of circle energy in far-field and other beam evaluation factors can also be obtained by further calculation, so beam mode properties and quality can be analyzed comprehensively. Experimental results illuminate that wavefront aberration of the laser is concentrated in the frontal 10 ranks of Zernike aberration, mainly including the defocus Z3, the low-order astigmatism Z5, the coma aberration Z6 and the spherical aberration Z10 because of the crystal thermal effect and the intracavity phase perturbation.