Mutually-Pumped Phase Conjugation in Photorefractive Materials.

In this dissertation we investigate a nonlinear optical process, mutually-pumped phase conjugation (MPPC), in photorefractive materials. MPPC is a process that is mutually pumped by two incoherent laser beams and generates two phase conjugate waves simultaneously. This process is studied from three perspectives: (i) Using the coupled wave theory, we develop a two-interactive region model to analyze the steady-state properties of MPPC. Comparative studies are carried out among different configurations. The experimental data are well fitted to the theory. (ii) We investigate the transient build-up processes of a MPPC by solving the four-wave mixing equations coupled with the evolution of the space-charge electric field in photorefractive materials. The build-up time is studied with respect to various parameters. (iii) A photorefractive MPPC device is shown and demonstrated experimentally as a high throughput two-way reconfigurable communication device that may be used in high-efficiency atmospheric optical communication applications. The amplification and the coherent detection schemes are proposed and demonstrated experimentally. We also introduce and demonstrate a new configuration of photorefractive MPPC: Semilinear Double Phase Conjugate Mirror (SDPCM). The experimental study shows that it exhibits high phase conjugate reflectivities, good phase conjugate fidelity, wide acceptance angle, large dynamic range and relatively fast time response.