Light-induced domain reversal in doped lithium niobate crystals

Light-induced domain reversals of Mg-doped, Zr-doped, and nominally pure LiNbO3 crystals were investigated with focused 514.5 nm laser beams. It was found the light-reduced values of electric field for domain reversal are almost the same, about 3 kV/mm. Inverted domains always first nucleate on the −c surface within the illuminated region but appear at the edge of the spot on the +c surface. The light-induced inverted domains are hard to be reversed by application of a reverse electric field or by heating to temperatures as high as 600 °C. According to these experimental results, we present a qualitative model on the light-induced domain reversal process in LiNbO3.