Eyesafe laser diode arrays for resonant pumping of Er-doped gain media optimized for cryogenically cooled operation

Growing interest to high power lasers in the eye-safe spectral domain has initiated a wave of activity in developing solid-state lasers based on Er3+-doped materials. Impressive results have been demonstrated in resonantly pumped Er:YAG based lasers. Cryogenic cooling of the laser crystal has improved the laser performance. In these experiments the pump lasers are InGaAsP/InP based 1530 nm laser diode arrays operating at room temperature. Operation of the pump laser diodes at cryogenic temperatures will provide significant benefits for the complete system. This includes increased pump power, improved laser efficiency and a compact optical system. The design of the pump laser for cryogenic operation requires modification of the existing structure. The modifications will be based on both the analytical models as well as data measured on current devices. The design optimization will focus on improving output power and wall plug efficiency for operation at cryogenic operation. The goal of the program is to deliver a laser diode array with output power of 50W and a wall plug efficiency of >60%.