TEMPERATURE AND THERMAL-STRESS SCALING IN FINITE-LENGTH END-PUMPED LASER RODS

Thermal effects lead to upper limits on the maximum achievable power in end-pumped solid-state laser rods. Thermal fracture is an ultimate limitation on pump power, while optical distortions and depolarization leading to increased losses in the laser resonator tend to yield a lower upper bound on the pump power. In this paper we derive the relevant optical distortion profiles and maximum stresses as a function of length-to-diameter ratio and pump spot size. Length-to-diameter ratios up to 1.5 are considered. Edge-cooled and face-cooled active-mirror geometries are analyzed and compared directly. The problem is cast into a nondimensional form so that the results are applicable to arbitrary rod materials.