Multiple pulse laser-induced damage phenomena in silicates.

Multiple pulse laser-induced bulk damage has been studied in fused silica and borosilicate glass. The fluence dependence and pulse repetition frequency dependence of the damage make it clear that laser irradiation promotes damage on subsequent pulses, and the evidence favors attribution of the effect to transient entities such as point defects rather than larger imperfections such as inclusions. However, the influence of preirradiation defects on damage thresholds is small, and a luminescence experiment places low limits on the possible concentration of conduction band electrons prior to damage. The constraints these results place on possible mechanisms of multiple damage are briefly discussed.