600  W green and 300  W UV light generated from an eight-beam, sub-nanosecond fiber laser system

We describe a sub-nanosecond pulse laser system that delivers high-average-power green and ultraviolet (UV) light. This system includes a front end, two modules each of which has four photonic crystal fiber main amplifiers, two sets of coherent beam combiners with efficiencies of 83 and 90%, and two sets of harmonic converters. A single beam was ultimately produced through polarization-beam combining. The maximum average output power was 955 W at the fundamental wavelength (1040 nm) with a 10 MHz repetition rate and 285 ps pulse duration. The M-square of the UV was 1.3. The average power of each of its harmonics is 600 W in green (520 nm) and 300 W in UV (347 nm). The nonlinear crystals were longitudinally cooled by Peltier devices for efficient harmonic conversion.