A nonlinear optical effect in which a linearly polarized wave propagating in a single quadratic medium is converted into a wave that is cross polarized to the input wave is investigated theoretically and observed experimentally in β-barium borate crystal. It is proved that this effect is a result of cascading of two different second-order processes. It starts with the generation of an extraordinary second-harmonic wave by type I interaction and is followed by type II difference-frequency mixing between the second-harmonic wave and the ordinary fundamental wave. The experiment was performed (a) for phase-matched type I interaction and non-phase-matched type II interaction and (b) for non-phase-matched type I interaction and phase-matched type II interaction. The observed generation of a cross-polarized wave is to our knowledge the only cubic effect whose first manifestation has been observed in quadratic crystal.
© 2002 Optical Society of America
(190.4360) Nonlinear optics : Nonlinear optics, devices
(190.4380) Nonlinear optics : Nonlinear optics, four-wave mixing
(200.4740) Optics in computing : Optical processing
(230.5440) Optical devices : Polarization-selective devices
G. I. Petrov, O. Albert, N. Minkovski, J. Etchepare, and S. M. Saltiel, "Experimental and theoretical investigation of generation of a cross-polarized wave by cascading of two different second-order processes," J. Opt. Soc. Am. B 19, 268-279 (2002)