Experimentation and Investigation of Optical-Irradiation-Induced Surface Damage in Optically Nonlinear Materials

Abstract : Surface damage to optically nonlinear materials has been studied both experimentally and theoretically. A model for the damaging process, based on the probability measurements and electron avalanche breakdown, has been devised. In its simplest form, this model has successfully explained the most important properties of the measured damage probability in over 10 different materials. This model is being refined to examine such areas as the dependence of damage probability on laser frequency and the temporal distribution of breakdown starting times. The present program has also explained the difference between damage produced by multimode and TEM(00) mode laser beams, shown that the form of damage (whether on the surfaces or in the volume) depends on the laser beam geometry and has demonstrated, using streak camera photography, the upstream movement of the beam focal point under self-focusing conditions. In addition, a refined theoretical analysis of self-focusing with both instantaneous and finite response-time mechanisms has been developed.