High-power continuous-wave narrow-linewidth 253.7 nm deep-ultraviolet laser.

A 760 mW stable continuous-wave narrow-linewidth 253.7 nm deep-ultraviolet laser is developed for laser cooling of mercury atoms. It is based on a high-power 1014.8 nm room-temperature fiber laser amplifier and two cascaded efficient frequency-doubling stages. The saturated absorption spectrum of Hg202 on the 6S1-6P3 transition is demonstrated with a high signal-to-noise ratio. This deep-ultraviolet laser has significant applications in quantum optics and laser cooling of mercury atoms in 2D and 3D magneto-optical traps.