Theoretical Analysis of Electronic Structure and Optical Properties of Potassium Dihydrogen Phosphate Crystal Affected by [011] Screw Dislocation

The atomic configurations, energetics, electronic structures, and optical properties of [011] screw dislocation in the KDP crystal have been analyzed by using density functional theory with Perdew–Burke–Ernzerhof and HSE06 functionals. The results have confirmed that the [011] screw dislocation reduces the band gap and introduces the intermediate states into the forbidden gap, which are principally derived from 2p (O)–3p (P) hybridization. Extra optical absorption peaks are also introduced at 170, 220, and 270 nm, which may be attributed to the dehydration process, and PO2 radical emerged near the dislocation core in the KDP crystal. The [011] screw dislocations will contribute to a large nonlinear absorption, enhance the crystal to absorb more laser energy, and decrease the laser-induced damage threshold of the KDP crystal. These findings will also contribute to our understanding of the root of the extra 270 nm absorption peak in practice and provide a basis for methods to improve laser-induced damage threshold of KDP or DKDP in frequency conversion devices.