We derive general boundary conditions for optical rectification of Gaussian beams and discuss the effect on cascaded optical rectification and the linear electro-optic effect as well as terahertz generation. These conditions are applied to degenerate four-wave mixing in a novel geometry in which we experimentally demonstrate, for the first time to our knowledge, that the combination of optical rectification of a single pump beam and the linear electro-optic effect produces a refractive-index grating in the transparent spectral region of the inorganic crystal KNbO<sub>3</sub>. The intensity of a probe beam diffracted by this grating was determined and corresponds to the theoretically expected result obtained from the known material parameters.
© 2001 Optical Society of America
(070.4340) Fourier optics and signal processing : Nonlinear optical signal processing
(160.2100) Materials : Electro-optical materials
(190.0190) Nonlinear optics : Nonlinear optics
(190.4380) Nonlinear optics : Nonlinear optics, four-wave mixing
(190.4400) Nonlinear optics : Nonlinear optics, materials
Rolf Spreiter, Christian Bosshard, and Peter Günter, "Boundary conditions for optical rectification and application to degenerate four-wave mixing in a novel geometry," J. Opt. Soc. Am. B 18, 1311-1317 (2001)