Stability analysis of a diode-pumped, thermal birefringence-compensated two-rod Nd:YAG laser with 770-W output power

Using a ray matrix method, we analyze theoretically how the r and theta polarizations affect the resonator stability condition of two laser heads with or without thermal birefringence compensation. The resonator stability condition is analyzed graphically for a plane-parallel and a concave-concave resonator. The maximum range of stable region is found for both the short and the long cavity. The characteristics of the laser output power are confirmed experimentally in association with the resonator stability condition. The laser output power of 776 W is obtained with the optical-to-optical efficiency of 45% for a plane-parallel resonator with a short crystal separation.