Noise shear waves in nonlinear smectic liquid crystal

Study is made of a narrow-band shear wave in smectic liquid crystal. It is shown that a random phase modulation is possible on account of non-linearity. A time correlation function, characteristic correlation time and spectrum width have been calculated. The relationship between the spectrum width, wave intensity and distance covered is determined. It allows the coefficient of cubic non-linearity of smectic liquid crystal to be determined by measuring a relative spectrum width increase at an arbitrary point.