Piezoelectric modulation of nonlinear optical response in BaTiO3 thin film

Abstract

We study the nonlinear optical response in a strained thin film ferroelectric oxide BaTiO3 using piezoelectric Pb(Mg1/3Nb2/3)O3-PbTiO3 (001) as a variable strain substrate and La-doped SrTiO3 as a conductive buffer layer. The rotation-anisotropic second harmonic intensity profile shows hysteretic modulation corresponding to the strain variation from the inverse piezoelectric response of the substrate. An enhancement of 15% is observed at 1.2 kV/cm, while a control sample shows negligible change as a function of piezovoltage. Reflection high-energy electron diffraction, x-ray photoelectron spectroscopy, and high-resolution scanning transmission electron microscopy reveal the epitaxial interface. X-ray diffraction and piezoresponse force microscopy confirm tetragonal distortion and ferroelectricity of the BaTiO3 overlayer. Our results suggest a promising route to enhance the performance of nonlinear optical oxides for the development of future nano-opto-mechanical devices.