Degenerate stimulated parametric scattering in LiTaO(3)

Degenerate nonlinear light scattering in LiTaO(3) caused by parametric forward four-wave mixing of waves with orthogonal polarization is reported. Scattered light is located on a cone whose apex angle is defined by the phase-matching condition. The photorefractive-type nonlinearity involved in this process is caused by the excitation of spatially oscillating photovoltaic currents directed normal to the optical axis and the subsequent formation of a volume space-charge field modulating the refractive index.