Spike suppression and longitudinal mode selection in a 1.319 μm Nd:YAG laser by high-efficiency intracavity frequency doubling

We describe a flashlamp pumped 1.319 μm Nd:YAG ring laser in which a high-efficiency intracavity frequency doubler is used as a nonlinear output coupler, virtually eliminating all spiking behavior and providing longitudinal mode selection as well. A single frequency, long pulse (>50 μs) output at 660 nm with about 20 W peak power is produced, suitable as a source for visar and other applications where long coherent pulses at relatively high power are required. Experimental results and theoretical analyses are given.