Amplification of microchip oscillator emission using a diode-pumped wedged-slab amplifier

A master-oscillator power-amplifier (MOPA) system combines a 1064-nm microchip laser oscillator with a new diode-side-pumped Nd:YVO4 zig-zag slab amplifier design. With 40 W of diode pump power, the amplifier increases microchip average power from 200 mW to more than 2.5 W at a 10-kHz pulse rate for a single pass through the amplifier, and to 5.7 W for two-passes, while preserving microchip laser beam quality and emission spectrum. Pulse energy of more than 800 μJ was achieved at a 2-kHz pulse rate. These results are the highest reported to date in an amplified microchip laser system. The 15-mm-long Nd:YVO4 slab has thin-film-coated lateral sides that enable a zig-zag gain length longer than 5.5 cm for a single pass through the slab, which is the longest reported to date. The unique slab design has non-parallel or wedged lateral sides to prevent build-up of amplified spontaneous emission. The two-pass beam is separated from the input beam without using a Faraday device.