Pulsewidth dependence of laser damage in fused silica

Summary form only given. The availability of ultrafast sub-50 fs lasers and the technology of chirped-pulse amplification have extended the study of the pulsewidth dependence of damage to ultrashort time scales. Various groups have reported two remarkable features of ultrashort pulse damage. First, short pulse damage exhibits a deterministic nature as opposed to the statistical behavior for long-pulse damage. Second, damage threshold fluence is higher than the prediction from the /spl radic//spl tau/ scaling rule for pulsewidth /spl tau/<10 ps. However, these measurements display different pulsewidth dependence of damage threshold in the subpicosecond regime. None of the theoretical models proposed before can explain this dissimilarity. The discrepancy among observations was thought to arise from different experimental conditions for instance, the number of laser shots. The sample may suffer a cumulative change in material properties as it is subjected to a series of subthreshold pulses. In order to study intrinsic laser damage, and to exclude the complexity of cumulative effects, our recent measurement was done under single-shot conditions.