Orthogonally polarized four-wave mixing involving two noncoupling waves in a photorefractive crystal

Orthogonally polarized four-wave mixing is studied theoretically in a configuration involving two coupling coefficients with different magnitudes, one of which is effectively zero. The configuration is studied to reduce the complexity of the feedback and to achieve a unidirectional power flow from one of the pumps to the diffracted wave. The analytical solution of the coupled-wave equations is derived for both a transmission-type grating and a reflection-type grating. The solution clearly explains the relative phases between the two components of a grating and its effect on the performance of the system. Phase matching is also studied. For characterization of its operation, diffraction efficiency and diffracted-beam reflectivity are calculated, plotted, and analyzed as functions of different quantities, such as coupling strength, probe ratio, pump ratio, and angular difference of the waves. A signal distributor as a possible application is also discussed. (C) 1998 Optical Society of America.