Two-dimensional polarization holographic recordings in azobenzene liquid-crystalline polymer thin films

Two-dimensional （2D） polarization holographic recordings were accomplished in azobenzene side-chain liquid-crystalline polymer thin films. The 2D polarization grating makes up of two orthogonal 1D polarization gratings, which were written at the same place by two orthogonally linearly polarized 532 nm beams. It is found that the diffraction efficiency of 2D grating is lower than that of 1D grating, and the 2D grating acts as the integration of its componential 1D gratings. Furthermore, we find that the polarization dependency of diffraction efficiency and the polarization conversions arise from the collaboration of linear and circular birefringence.