Investigation of a 100 W Solar-Pumped Disk Laser with TEM00 Output

To improve the output power of solar-pumped lasers, we propose a new configuration of solar disk laser. A rotating parabolic reflector acts as the primary concentrator with top and bottom radii of 1600 and 600 mm, respectively. The incident sunlight is reflected by the primary concentrator to the inlet of the heteromorphic compound parabolic concentrator (HCPC) and is absorbed by the gain medium after multiple reflection. The diameter, thickness, and doping concentration of the Nd :YAG disk are 20 mm, 1 mm, and 1.0 at.%, respectively. The two surfaces of the disk are cooled by heavy water. Owing to the increased surface area of the disk for receiving sunlight, solar absorption by the gain medium is greatly improved. Ray tracing shows that maximum absorbed solar power by the Nd :YAG disk can reach 446 W through optimizing the HCPC. Solving rate equations, we obtain the laser output power in the TEM00 mode as high as ∼123 W, with a conversion efficiency of ∼27%. In addition, we analyze the temperature distribution of the solar-pumped Nd :YAG disk laser. The design of this solar concentrating system and the over-hundred-watts disk laser provides a new idea for further scaling the output power of solar-pumped solid-state lasers.