Nonlinear optical properties of undoped and doped with Zr and Nb KTiOPO4 crystals

Abstract

The structure of the ferroelectric phase of undoped KTiOPO₄ and its solid solutions with zirconium and niobium is studied from first principles within the density functional theory. The second-order nonlinear susceptibility tensor and the spontaneous polarization of these materials are obtained. It is shown that an improvement in nonlinear optical properties of KTiOPO₄ upon doping it with Zr and Nb cannot be explained by a systematic change in the composition of crystals and is apparently associated with the occurrence of defects. Possible structures of such defects are discussed.