Laser Induced Bulk Damage in SiO₂ at 1.064, 0.532 and 0.355 μm

In this paper we present bulk damage measurements of crystalline quartz and fused silica under single and multiple pulse irradiation where the wavelength was extended to 0.355 μm. In previous work under irradiation at 1.06 and 0.532 μm, it was shown that whereas the single pulse damage varies little with material or wavelength, the multiple pulse damage depended strongly on both. Also, in the case of multiple pulse damage the distribution of the number of pulses needed to produce damage as a function of intensity is indicative of an accumulation process.

If the present work at 0.355 μm the multiple and single pulse damage dependence on focal spot-size, pulse duration and pulse repetition frequency is examined, it is found that the multiple pulse damage shows a much stronger dependence on material, spot-size, pulse duration and wavelength than does the single pulse damage. In addition, more pulses are needed to produce macroscopic damage at a given intensity under irradiation at a 1 Hz pulse repetition rate than at 10 Hz. Possible mechanisms of the repetition rate dependence are briefly discussed.