Watt-level green random laser at 532 nm by SHG of a Yb-doped fiber laser.

We have developed a watt-level random laser at 532 nm. The laser is based on a 1064 nm random distributed ytterbium (Yb) gain-assisted fiber laser seed with a 0.35 nm linewidth and 900 mW polarized output power. A study for the optimal length of the random distributed mirror was carried out. A Yb-doped fiber master oscillator power amplifier architecture is used to amplify the random seeder laser without additional spectral broadening up to 20 W. By using a periodically poled lithium niobate crystal in a single-pass configuration, we generate in excess of 1 W random laser at 532 nm by second-harmonic generation (SHG) with an efficiency of 9%. The green random laser exhibits an instability <1%, an optical signal-to-noise ratio >70  dB, a 0.1 nm linewidth, and excellent beam quality.