Method of producing crystalline rods having regions of reversed dominant ferroelectric polarity and method for clarifying such a rod

摘要

A method of growing a single crystal rod with regions of reversed dominant ferroelectric polarities (poling the same) is described. It is a variation of laser-heated pedestal growth. The microscopic growth rate of the crystal is modulated to incorporate into the rod, the compositional melt gradient which is formed at the freezing interface. When this gradient is of the proper sign and the poling action due to it is of sufficient strength to overcome the normal poling action with which the rod would otherwise grow, it defines a reversed domain region. This region is reduced in temperature to below the Curie temperature before the gradient responsible for the same can diffuse. A method of clarifying a single crystal to make the same transparent to optical radiation of interest is also described.