Abstract

We present the first observation of two-wave mixing using the moving grating technique that has recently been studied widely by Huignard et al. in BSO crystals. We have observed a more than 100% gain in a weak probe beam using a pump beam intensity of the order of a few watts/cm² in a 100-μm thick nematic liquid crystal film. The gain experienced by the probe beam is very sensitive to the frequency shift of the probe beam (created by translating the beam at a rate of ~1 wavelength/s), to the crossing angle of the two beams, to the thickness of the sample and the sign of the frequency shift. We have developed a detailed theory for the dynamics of the grating formation and the magnitude of the probe beam gain vs the physical parameters mentioned above. Experimental results are found to be In good agreement with theory.

© 1986 Optical Society of America