Influence of spherical aberrations on fundamental mode beam quality under different laser resonators

Spherical aberrations of the thermal lens of the active media are severewhen solid state lasers are strongly pumped. The fundamental modeprofile deteriorates due to the aberrations. Self-consistentmodes of a resonator with aberrations are calculated by using theFox--Li diffraction iterative algorithm. Calculation results showthat the aberration induced fundamental mode beam qualitydeterioration depends greatly on the resonator design. The toleranceof a flat--flat resonator to the aberration coefficient is about30$lambda $ in the middle of stability, where $lambda $ is thewavelength of laser beam. But for a dynamically stable resonator,2$lambda $ of spherical aberration will create diffraction loss ofmore than 40{%}, if inappropriate design criteria are used. Abirefringence compensated laser resonator with two Nd:YAG rods isexperimentally studied. The experimental data are in quite goodagreement with simulation results.