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

TL;DR

This study uses first-principles calculations to analyze the nonlinear optical properties and ferroelectric phase structure of undoped and doped KTiOPO4 crystals, highlighting the role of defects in property enhancement.

Contribution

It provides a detailed first-principles analysis of how Zr and Nb doping affects the nonlinear optical properties and defect structures of KTiOPO4 crystals.

Findings

Doping with Zr and Nb does not systematically change the composition-related properties.

Improvement in nonlinear optical properties is linked to defect formation.

Defect structures potentially responsible for property enhancement are discussed.

Abstract

The structure of the ferroelectric phase of undoped KTiOPO$_4$ 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 KTiOPO$_4$ upon its doping 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.