An Investigation of the Possibility that Laser-Induced Color Centers are Responsible for Multiple Pulse Damage

The mechanisms responsible for multiple pulse laser damage in transparent solids are still not understood. Recent reports related to laser generation of point defects in fused silica and BK-7 glass raise the possibility that such defect generation is the cause of multiple pulse damage. The difference in defect generation between high-OH and low-OH fused silica offers a means to test this possibility.

We have compared multiple pulse damage properties of “wet” and “dry” fused silica at 1064 nm and 532 nm. Nearly identical behaviors are observed for the two materials. In addition we have studied laser damage in BK-7 X-irradiated to produce color centers. The presence of these centers lowers the damage threshold only modestly. We conclude that optical generation of color centers is not the primary mechanism in multiple pulse damage in these materials.