The effect of the ferroelectric domain walls in the scanning near field optical microscopy response of periodicallypoled Ba2NaNb5O15 and LiNbO3 crystals

Abstract

A study of Ba2NaNb5O15 and LiNbO3 crystals with periodic ferroelectric domain structures using the scanning near field opticalmicroscopy technique is reported. Optical contrast is observed in the regions of ferroelectricdomain boundaries and it is analysed using beam propagation method modelling. Thisreveals that the optical contrast, a consequence of changes in the refractive index, is notdue to variation of the waveguide-coupling efficiency, and supports the hypothesis that it isassociated with the domain array, which is related to the size of the domain.