We demonstrate a robust linearly polarized 365 W, very low amplitude noise, single frequency master oscillator power amplifier at 1064 nm. Power scaling was done through a custom large mode area fiber with a mode field diameter of 30 µm. No evidence of stimulated Brillouin scattering or modal instabilities are observed. The relative intensity noise is reduced down to −160 dBc/Hz between 2 kHz and 10 kHz via a wide band servo loop (1 MHz bandwidth). We achieve 350 W of isolated power, with a power stability < 0.7% RMS over 1100 hours of continuous operation and a near diffraction limited beam (M 2 < 1.1).

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.

We demonstrate a 17 W single-frequency, low-intensity-noise green source at 532 nm, by single-pass second-harmonic generation of a 50 W continuous-wave fiber laser in a 30 mm MgO-doped periodically-poled stoichiometric lithium tantalate crystal. The maximum conversion efficiency is about 37%. A nearly Gaussian beam ( M 2 <2020