Uniform Side-Pumping of Solar Solid-State Laser Based on Fresnel Lens Array

Uniform side-pumping can reduce the thermal stress of laser crystal rod and is an effective method to achieve high power laser output. In order to realize the uniform side-pumping of the laser crystal rod, a solar concentrating system based on plane mirrors and linear Fresnel lens array is proposed. Rays tracing shows that the concentrating efficiency of solar concentrating system and the uniformity of the light spot reach 66.5 and 98.5% with optimization. The temperature distribution in the laser crystal rod is calculated by Comsol software. The results show the central temperature and the surface temperature of laser rod are 316 and 306 K, respectively. Base on solving the rate equations, the laser output characteristics are analyzed. The laser output power and the solar-to-laser conversion efficiency are 88.5 W and 3.3%, respectively. This uniform side-pumping configuration provides the new method for developing high power solar-pumped solid-state lasers.