Determination of the Linear Electrooptic Coefficient of a Lead Zirconate Titanate Thin Film Using Two-Beam Polarization Interferometer with an Adaptive Photodetector

A novel interferometric modulation technique for optical thin-film testing using a two-beam polarization (TBP) interferometer with GaAs:Cr adaptive photodetector is presented. The technique enables determination of Pockels coefficient of thin films with a strong Fabry Perot effect and automatic adjustment and maintenance operation point of the interferometer. We use this method for measuring the effective differential linear electrooptic coefficient r(e) = r(33) - (n(0)/n(e))(3)r(13) Of lead zirconate titanate (PZT) thin film. A strong hysteresis effect with a slightly asymmetric form of the hysteresis loop was observed for the dependence of the effective differential Pockels coefficient of the PZT thin film on the DC electric field. The values of r(e) are in agreement with known data.