Research progress on the high power flowing-gas circulation diode-pumped alkali vapor laser (Invited)

Diode pumped alkali metal vapor laser (DPAL) combines the technical characteristics of both diode laser and gas laser, with the advantages of high quantum efficiency, large excited emission cross section, small refractive index perturbation, convenient thermal management and rich output wavelength, which can achieve high efficiency, high power and high beam quality near infrared laser output, and has important applications in industrial manufacturing, military, medical and scientific research fields. For closed static DPAL, under the condition of high power pump, the working gas temperature in the steam pool increases, and the thermal effect is serious, resulting in the decline of DPAL performance. The circulating flow DPAL uses gas flow to take away waste heat, which can significantly alleviate the thermal effect of working gas, so as to achieve high-power laser output. At present, it has become the mainstream technical route to achieve high power laser output. In this paper, the principles and current development of the flowing-gas circulation DPAL are outlined, the obstacles and solutions of high power scaling of DPAL are analysed, and prospects for the future development of high-power alkali metal lasers.