Effect of Cr3+ Dopant on Growth Habit and Optical Properties of Rapid Grown KDP Crystal

KDP crystals were grown by rapid growth method in the presence of different concentrations of Cr3+. Both the growth rate and dead zone influenced by Cr3+ was measured, and the Cr3+ element distribution, UV―Vis transmission spectra, distribution of scatter particles and laser induced damage threshold were characterized as well. The results reveal that Cr3+ is prone to be absorbed onto (100) face, which decreases the growth rate and extends the growth dead zone. Additionally, Cr3+ can induce growth macroscopic growth boundaries between prismatic and pyramidal growth sectors. The element analyses of Cr3+ suggest that Cr3+ is inclined to enter into prismatic sector, which leads to a decrease of transmittance in visible light and ultraviolet band, and brings three strong absorption peaks at 220 nm , 450 nm and 650 nm. The entrance of Cr3+ into crystal lattice can increase the number of scatter particles and decrease laser induced damage threshold. The laser damage threshold at fundamental frequency and the third harmonic generation decrease with the increase of Cr3+ concentration. The damage threshold of KDP prismatic sector is lower than that of pyramidal sector.