High-Power Dual-Wavelength Laser Based on Coaxial End-Pumping Scheme With Combination of Gain Media

A high-power dual-wavelength laser based on coaxial end-pumping scheme with composite Nd:YAG and Nd:YAP crystals was demonstrated. A theoretical model was built to analyze the thermal lens and accurately calculate the thermal focal length of laser gain medium pumped by a divergent beam. The experiment was carried out with a plane-convex cavity and a V-shape cavity for high-power output. The Q-switched laser produced 9.1 W pulsed dual-wavelength output (4.7 W at 1064 nm and 4.4 W at 1079 nm) at 25-kHz pulse repetition rate with synchronized pulse duration of 35 ns, corresponding to the optical-to-optical efficiency of 30.3%. The continuous-wave (CW) output power reached 15.5 W at laser diode (LD) pump power of 40 W, corresponding to a slope efficiency of 40.9% and an optical-to-optical conversion efficiency of 38.9%. The powers at two wavelengths were almost equivalent and the fluctuations were both less than 2.3%. To our best knowledge, it was the highest output power for stable CW dual-wavelength lasers based on diode-end-pumped configuration.