Evolution of laser-induced bulk damage in KDP crystal

Abstract

Pinpoint damage is the main type of bulk damage in potassium dihydrogen phosphate (KDP) crystals in high-power lasers. Using time-resolved microimaging, we observed the complete dynamic evolution of pinpoint damage in a KDP crystal. We analyzed changes in the patterns of dark zones formed by decreasing probe transmittance in transient images throughout the process. The mechanical properties of stress waves in KDP crystals were further studied by a depolarized shadowgraph experiment and theoretical simulation. The dynamic evolution of mechanical stress waves was observed, and the correlation between mechanical failure due to stress waves and the static characteristic damage morphology was established.

Investigation of the photothermal weak absorption and laser damage characteristics of a Nd,Y:SrF2 crystal

“…Alternatively, laser gain devices continuously absorb pump light and emit laser pulses that have extremely high power density and strong electromagnetic field during their operation, 15 and therefore, high laser damage resistance is one of the basic requirements for novel gain materials such as NYSF crystals with a higher pulse energy and repetition rate when applied in laser facilities. Indeed, numerous studies on laser damage phenomena have been reported, focusing on several important optical components in high-energy laser techniques such as KDP crystals, [23][24][25] Nd 3+ -doped phosphate glasses 26,27 and fused silica. 28,29 The proposed laser damage mechanisms based on these studies are important for enhancing the laser damage threshold of optical components, which can be achieved by minimizing the defects that contribute to laser damage during their synthesis and processing.…”