Laser-induced damage in quartz: A study of the influence of impurities and defects

It has been observed that samples of high-quality cultured quartz can differ markedly from sample to sample in their resistance to laser-induced catastrophic damage. The bulk damage properties of quartz from several sources have been investigated using both 1064- and 532-nm laser pulses. It is found that the single-pulse damage "threshold" is ill defined, indicating considerable inhomogeneity in even the best samples. Neither resistance to damage by a single-pulse nor damage behavior under multiple-pulse irradiation exhibit any correlation with the concentrations of Al or OH, two impurities important to other properties of quartz. Further, the dependence of damage resistance on temperature and on electron irradiation is much weaker than would be expected if Al were important to the damage process. However, there does appear to be a correlation with the density of coarsely spaced defects revealed in the damage morphology and in chemical etching. Thus, it appears that even in high-quality quartz-laser-induced damage is initiated on low-concentration defects, but that the relevant defects are not related to aluminum impurities.