Toward 10 W-level all-fiber multi-color visible lasers.

So far, high-power visible laser generation has traditionally relied on nonlinear frequency conversion of near-infrared lasers, precluding efficient, compact, and affordable laser systems. An ideal solution is a rare-earth-doped fiber laser for directly generating visible light, but the output power is limited to the watt level, and the all-fiber structure is rarely reported. Here, we address this challenge by demonstrating high-power all-fiber visible lasers, directly generating either 10 W-level output power at 635 nm (red)/717 nm (deep-red) and 5 W-level output power at 521 nm (green), respectively. This work involves theoretical optimization and experimental validation using 443 nm LD-pumped Pr-doped double-clad fiber. Greatly thanks to the self-design and homemade visible fiber dichroic mirrors with high damage threshold of >22.6 MW/cm, we successfully achieved the maximum laser output powers of 10.34 W at 635.6 nm, 10.28 W at 717.2 nm, and 4.87 W at 521.4 nm, respectively, with the slope efficiency of 26.5%, 24.4%, and 21.4%. Moreover, the all-fiber visible lasers show excellent stability with power fluctuation of 0.93%, 0.33%, and 2.8%. To our knowledge, this is the highest visible CW output power directly generated in a compact all-fiber laser and represents an important step towards the 10 W level.