Photoinduced domains in lithium niobate

We have observed the optically induced occurrence of domain structure with polarization opposite to the spontaneous polarization of a single-domain sample of lithium niobate. The appearance of the domains can be explained by a redistribution of the density of the Fe²⁺ and Fe³⁺ impurity ions under the action of the photoinduced field and subsequent additional inverse polarization of the environment surrounding the Fe²⁺ ions. Fiz. Tverd. Tela (St. Petersburg) 40, 531–533 (March 1998)