Crystals of potassium dihydrogen phosphate (KDP) are routinely used for harmonic conversion, but damage-resistant antireflection coatings for these water soluble crystals are not currently available. To reduce insertion losses in conversion cells, the crystals are immersed in an index-matching liquid in a cell having windows with antireflection coatings. We have studied laser-induced damage in many 5-cm aperture conversion cells filled with either fluorocarbon or hydrocarbon liquids or with a saturated solution of water and KDP. The damage tests were performed with 1-nsec 1064-nm pulses in a collimated 20-mm diam beam at input fluences up to 8 J/cm2. In some tests the cells were angle-tuned for phase-matched production of outputs at the second or third harmonic. Test sites were repeatedly irradiated until damage occurred or until a preselected number of shots failed to cause damage.
© 1984 Optical Society of AmericaPDF Article