Energy exchange between optical waves counterpropagating in a cholesteric liquid crystal

The interaction between optical waves counterpropagating in a cholesteric liquid crystal, due to the excitation of orientational gratings and resulting in stimulated scattering of the exciting waves, was detected experimentally and investigated. This interaction process occurred at relatively low intensities because of the proximity of the radiation wavelength to a selective reflection band of the cholesteric liquid crystal. An investigation was made of the concomitant phenomena of self-focusing and nonlinear rotation of the polarization of the exciting radiation