Correlation between laser-induced damage densities of fused silica and average incubation fluences at 1064 nm in the nanosecond regime

The chronology of the physical processes involved in the nanosecond laser damage of fused silica is investigated at 1064 nm. From experiments realized with multiple longitudinal mode pulses, the correspondence between ring pattern damage morphology and the corresponding intensity profile allows the distinction of two damage phases: an incubation phase followed by a damage expansion phase that leads to the final damage diameter. It allows us to determine both the incubation and the expansion fluences. These results are compared to damage density measurements for different laser configurations, different optics, and different environments. It was found that damage densities were as high as incubation fluences were low. This approach shows a deterministic part of laser damage in nanosecond regime and contributes to reinforce the statistical results by reducing their random nature and is more able to guide the physical interpretations of laser damage experiments.