All-optically controlled beam splitting through asymmetric polarization-based holography.

All-optically controlled beam splitting is demonstrated by a tunable split ratio through polarization modulation. The beam splitters are essentially holographic gratings recorded by means of the interference of two 532 nm beams with asymmetric polarization states in an azobenzene liquid crystal film. It is found that the intensity ratio between zero and the first diffraction order is adjustable through the polarization manipulation of the recording light. An arbitrary split ratio from 0 to 1 is obtained with the photoinduced birefringence of the film being set to an appropriate value, which is independent on the polarization state of the probe light. Furthermore, the formation processes of the recorded beam splitters are contributed to the dual-grating coupling, and the tunable split ratio under various polarization conditions is discussed in terms of the Fresnel theory and Jones matrices.