Electrically-controlled wavefront modulators made with 180° domain-structures in congruently-grown LiNbO3

In this work we present electrically controlled wavefront modulators, such as diffusers, Fresnel zone plates and vortex-producing lenses, made from LiNbO₃ wafers containing 180° ferroelectric domains. Since the sign of the change of the refractive index produced by the linear electrooptic effect depends on the direction of the spontaneous polarization of the crystal, the wavefront of a beam incident on a z-cut LiNbO₃ wafer containing 180° ferroelectric domains will be modified if an electric field is applied to the wafer. The applied field and the direction of propagation of the beam incident on these modulators are parallel to the c-axis of the wafer.