Research development of 589 nm laser for sodium laser guide stars

In recent years, 589 nm lasers have attracted much attention in the fields of laser sodium guide star, laser radar, and adaptive optics. Therefore, the sodium guide star technology at 589 nm has been particularly topical. The sodium guide star technology requires that the average power should be Watt-level for the continuous-wave yellow laser which having narrow-linewidth and are capable of being tuned to match transition lines accurately. According to the generation method, the sodium guided star laser can be divided into four types: dye lasers, solid-state lasers, optically pumped semiconductor lasers, and fiber lasers. Solid-state laser includes sum-frequency generation, stimulated Raman scattering and optical parametric amplifier. Among them, sum-frequency generation lasers are used mostly. The development history and state of the art of them are expatiated, which is useful reference for the future research in this field.