Near field diffraction analysis of optical domain wall image in stoichiometric LiNbO3 crystal

Abstract

Observing diffraction patterns instead of direct measurement of domain wall morphology makes it possible to obtain effective in situ optical visualization of anti-parallel domains. Domain polarities are easily distinguished by applying proper voltage along the crystal z-axis. The polarization-dependent electro-optic effect gives opposite phase difference on probe beam at the anti-parallel domains, and maximum optical contrast is obtained at the 180° phase shift. The diffraction pattern width is minimal on the sample surface and diffused with the distance to the monitoring screen. Calculations based on the near field diffraction of the wave front are in good agreement with the experimental observations.