This program will involve experimental and theoretical studies of transient multiwave mixings in thin structures of highly nonlinear materials. The principal materials to be used in the experiments are liquid crystals, but some studies will also be extended to semiconductor materials to further establish the generality of the theories and observations. In these media, recent theories and experiments by the principal investigators have demonstrated that many useful multiwave mixing effects can occur efficiently in the stationary regime as well as in the transient regimes. The proposed studies will delve into several fundamentally interesting and important aspects of these effects, especially in the transient regime. These include: the roles played by intense temporal and spatial self- and mutual-phase modulations/shifts and side diffractions that invariably accompany efficient wave mixing in highly nonlinear thin materials; the interrelationship between the phase modulation effects and other geometrical/optical/material parameters such as the laser pulse width and intensities, material response time and nonlinearity (electronic, thermal, orientational, local or diffusive, etc.) the interaction length, wave mixing angle, anisotropy and birefringence, polarization, temperature, etc. This program of research will result in new fundamental measurements and theoretical formalisms for quantitative descriptions of, and application guidelines for, a broad new class of nonlinear devices including beam and image amplifiers, beam combining and steering, phase conjugator and self-pumped oscillators, based on coherent multiple wave mixing effects.
