Combining high power laser irradiation and emission spectra measurement system, the photoluminescence properties of KDP crystal under high power laser irradiation were studied. Photoluminescence measurement was performed using 532 nm and 355 nm laser excitation at relatively high laser fluence but still under the laser induced damage threshold. Four emission peaks, centered at 559 nm, 586 nm, 609 nm and 621 nm, were observed while irradiated by high power laser at 532 nm. Five emission peaks, centered at 358 nm, 365 nm, 377 nm, 385 nm and 390 nm were observed under high power laser irradiation at 355 nm. Based on the analysis of wave number transformation, these peaks were attributed to the Raman scattering.
Transient transmission and scattering changes was observed to study the dynamics during the laser-induced bulk damage
in fused silica at the wavelength of 532 and 355 nm. Within the nanosecond high power laser irradiation, the
transmittance decreased dramatically, indicating an intense absorption. With fluence increasing, the time required to
form the intense absorption was shortened, and at similar fluence, this time interval at the wavelength of 355 nm is
shorter than that at 532 nm. At times, the intense absorption did not cause the macroscopic damage because no variation
in scattering was observed. While the macroscopic damage occurred, the scattering kept on increasing until the end of