We present a detailed theoretical analysis of degenerate four-wave mixing by a laser-induced thermal grating in a nematic liquid-crystal film. In particular, we show that the coupling of the (strong) pump beam to the first-order diffracted beam can give rise to substantial amplification of a (weak) probe beam. Experimental verification of this effect with a CO2 laser beam is also made. A probe-beam gain of greater than 20 can easily be observed in a 120-μm film with a pump intensity of the order of a few watts per square centimeter.
|Original language||English (US)|
|Number of pages||5|
|Journal||Journal of the Optical Society of America B: Optical Physics|
|State||Published - Feb 1988|
All Science Journal Classification (ASJC) codes
- Statistical and Nonlinear Physics
- Atomic and Molecular Physics, and Optics