Diffraction of light on a regular domain structure with inclined walls in MgO : LiNbO$_3$

Features of the Bragg diffraction of a Gaussian light beam on a regular domain structure with inclined $180^\circ$ domain walls in a $5\%$ MgO : LiNbO$_3$ crystal have been studied experimentally and theoretically. The regular domain structure with a period of $8.79 \mu$m along the $X$ axis has been prepared by the polarization switching method under the action of an external electric field in a $1$-mm $Z$-cut plate. It has been shown that the inclination of walls of the regular domain structure by the angle $\alpha$ to the polar $Z$ axis results in the $m$th order Bragg diffraction characterized by the intensity distribution $I_m(z)$ with two maxima the spacing between which at $m = 1, 3, 4, \dots$ increases as $m\alpha$. The application of an external static electric field to the regular domain structure has allowed using the dynamics of the efficiency of the Bragg diffraction with $m = 1$ to detect the screening of this field associated with the conductivity of inclined domain walls. The effective value of this conductivity over the period $\Lambda$ for the studied regular domain structure with $\alpha = 0.31^\circ$ has been estimated as $\sigma_{\text{eff}}= 5.96\cdot10^{-11}\Omega^{-1}$ m$^{-1}$.