Effects of pulse duration on bulk laser damage in 350-nm raster-scanned DKDP

In this paper we present the results of bulk damage experiments done on Type-II DKDP triple harmonic generator crystals that were raster conditioned with 351 - 355 nm wavelengths and pulse durations of 4 and 23.2 ns. In the first phase of experiments 20 different scan protocols were rastered into a sample of rapid growth DKDP. The sample was then rastered at damage-causing fluences to determine the three most effective protocols. These three protocols were scanned into a 15-cm sample of conventional-growth DKDP and then exposed to single shots of a 1-cm beam from LLNL's Optical Sciences Laser at fluences ranging from 0.5 - 1.5X of the 10% damage probability fluence and nominal pulse durations of 0.1, 0.3, 0.8, 3.2, 7.0 and 20 ns. The experiment showed that pulse durations in the 1 - 3 ns range were much more effective at conditioning than pulses in the 16.3 ns range and that the multiple pass "peak fluence" scan was more effective than the single pass "leading edge" scan for 23.2 ns XeF scans.