High-gain end-pumped lasers

Summary form only given. New-generation diode pump sources allow end-pumped cw lasers to achieve gain levels previously reached only in quasi-cw diode-pumped systems. We report end-pumped lasers with single-pass small signal gain G=10, producing Q-switched output at the 16-W level in 6-ns pulses at 20 kHz. We achieved these results with a modified version of the Opto Power Beam Shaper, capable of producing a pump beam of 200 /spl mu/m diameter, near collimated over a 10-mm interaction length in an Nd:YVO/sub 4/ laser crystal. The modified beam shaper produces 17 W of highly polarized 810-nm output, which enables us to continuously vary the absorption of pump light in the YVO/sub 4/ crystal simply by polarization rotation (Nd:YVO/sub 4/ exhibits a factor-of-4 change in absorption for s and p polarizations). This quality allows optimization of the crystal doping levels without the need to physically sort through a series of different doping level samples.