Nonlinear acoustic-optical effect and extraordinary diffraction distribution in liquid surface

Nonlinear acoustic-optical effect is discovered by using a low-frequency liquid surface acoustic wave with great amplitude. There are higher harmonics in diffracted light and the intensity of the higher harmonic has the relation of Bessel's function with the amplitude. The light patterns diffracted by the wave can be classified into the ordinary and extraordinary beams which are corresponding to small and great amplitudes of the waves. The ordinary and extraordinary patterns are observed experimentally and the critical amplitude value is found.