Laser-induced surface damage of infrared nonlinear materials

Since the optical damage threshold limits the maximum efficiency of parametric processes in nonlinear materials, this parameter must be considered together with the nonlinear susceptibility tensor in evaluating the potential usefulness of such materials. In the present paper, the thresholds for surface damage caused by pulsed laser radiation at 10.6 microns were measured in four phase-matchable IR nonlinear materials: CdGeAs2, AgGaS2, AgGaSe2, and Tl3AsSe3. Because damage thresholds can be affected by experimental conditions, particularly the laser mode quality and pulse length, to obtain a standard of comparison, measurements on Ge (one of the most commonly used IR materials) also were made. In each case, the threshold for pit formation was found to be significantly lower than the threshold for visible plasma formation.