Dependence of the beam characteristics of the thermal-birefringence compensated symmetric resonator with two Nd:YAG laser rods on the curvature of laser-rod end surfaces

We investigated beam characteristics of the thermal-birefringence compensated symmetric resonator which consists of two Nd:YAG laser rods with rod-end curvatures. Numerical analyses show that the stability and the beam quality in high-power operation region can be improved when the rod-ends are made in the form of negative lenses. In addition, the thermal birefringence in the symmetric two-rod resonator is well compensated in the overall stable range when the two rods are located closely to each other.