Amplification of CW and high repetition rate pulsed radiation in an ultra-compact Nd:YAG planar waveguide power amplifier face-pumped by diode bars

Summary form only given. Recently we have reported operation of the planar waveguide type of Nd:YAG laser at up to 121 W CW output, using a 200 mm thick, 1.1 % at. Nd doped active layer, diffusion bonded to 400 /spl mu/m non-doped YAG claddings. This is face-pumped by ten CW diode bars in a configuration using a slotted -mirror pump chamber. The waveguide section is 11 mm/spl times/60 mm in area, with 50 mm pumped length. To demonstrate the power output and efficiency, the waveguide laser has initially been operated with external plane mirrors in a multi-mode cavity, showing that the laser is capable of sustaining continuous pumping without damage when mounted in a water cooled transverse flow pump chamber. An overall optical conversion efficiency of 28% has been achieved. We emphasise the excellent amplifier capabilities of the planar waveguide format. The active layer is currently pumped with a power density of 4 kW.cm/sup -3/, very much larger than conventional bulk rod and slab lasers. Consequently the CW gain coefficient is high, making the planar waveguide an ideal candidate for amplification of the low power diode pumped Nd:YAG now available using mini-rod or microchip configurations.