Seven-grooved-Ce:Nd:YAG-rod solar laser pumping approach with 34.5 W/m2 TEM00-mode collection efficiency

Abstract

Improving the TEM00-mode laser efficiency is one of the main goals in solar laser research, motivated by the significant importance these high-quality beams hold for fields, such as materials processing. A seven-rod concept was designed to enhance the TEM00-mode solar laser efficiency through the adoption of Ce:Nd:YAG active media. Collection and concentration of solar rays were conducted by seven Fresnel lenses, assisted by six folding mirrors. The laser head was composed of seven aspheric lenses, a hexagonal window and seven grooved Ce:Nd:YAG rods, which were end-side-pumped. A total TEM00-mode laser power of 172.59 W was numerically achieved, corresponding to a 34.52 W / m2 collection efficiency and a 3.63% solar-to-laser power conversion efficiency. These efficiency values were 1.51 and 1.59 times higher than those from the previous numerical study that also involved the usage of a grooved Ce:Nd:YAG rod. A laser beam merging scheme is also presented, enabling the extraction of a single TEM00-mode laser beam from the seven rods. A TEM00-mode laser power of 207.55 W was attained, corresponding to collection and solar-to-laser power conversion efficiencies of 41.51 W / m2 and 4.37%, respectively.