Abstract

A theory is presented of optical grating formation in a nonlinear medium consisting of a liquid suspension of colloidal particles.¹ The grating formation is due to radiation pressure, which causes the particles to migrate toward regions of higher light intensity, until thermal equilibrium is attained. We study the effects of particle interactions, particle diameter, the grating period, and interparticle correlations for four-wave-mixing geometries. The local field factors are also derived in the theory. Particle size and grating period effects are described by the intraparticle structure factor, which enters as its fourth power in the phase conjugate signal intensity. By contrast, the Rayleigh scattering depends only on the square of this quantity. The predicted effects are compared with recent experiments.^1,2

© 1988 Optical Society of America