Extraction of individual Pockels coefficients of thin films via interferometric reflection measurements

Abstract

Ferroelectric thin films integrated on passive photonic platforms offer ways to achieve functionalities that are otherwise impossible or inefficient, such as electro-optic (EO) modulation, acousto-optic modulation or optical nonlinear conversion. Characterization methods of the EO properties of thin films are often only able to extract an effective EO response, while in many integrated photonic circuits it is one of the Pockels coefficients that determines the strength of the modulation. In this work, we demonstrate a new method to extract the r33 and the r13 coefficient independently by measuring the change in polarization and amplitude of light reflected at the sample, taking into account multiple reflections and interference effects. This method is verified for highly textured Pb(Zr,Ti)O3 and BaTiO3 thin films.