A watt-level yellow random laser via single-pass frequency doubling of a random Raman fiber laser

Abstract We report a watt-level yellow random laser at 589 nm. The laser is generated by single-pass second harmonic generation of a half-open random Raman fiber laser at 1178 nm in a periodically poled stoichiometric lithium tantalite crystal. The major limitation on power scaling is the usual broad linewidth of random Raman fiber lasers. By counter pumping instead of common co-pumping, and using narrower fiber Bragg grating as the single mirror, the output spectrum of the 1178 nm random laser is greatly narrowed. As a result, up to 1.09 W 589 nm laser is obtained from a 10.1 W fundamental power with a conversion efficiency of 10.8%. The power and conversion efficiency are significantly improved compared to the previous report on frequency doubling of random Raman fiber laser.