以静态体光栅各向异性衍射理论分析模型为基础，将与体光栅厚度有关的记录光强调制度引入到各向异性耦合波方程中．利用耦合波理论分析了光折变晶体中体光栅的各向异性衍射性能，研究了在不同初始记录光强比的条件下，记录光入射角的改变对光折变体光栅各向异性布喇格衍射性能的影响．结果表明：记录光入射角和记录光初始光强比均对体光栅的各向异性衍射具有选择性；与此相比，记录光入射角和记录光初始光强比对于体光栅各向同性衍射不具备选择性．

Based on the model of anisotropic coupling theory,the initial intensity ratio of the two recording waves which was coherent to the length of the grating was introduced to the anisotropic coupling equations. The anisotropic Bragg diffraction properties of volume gratings in photorefractive crystals were investigated by the method of the couple wave theory. The effect both of the initial ratio of the intensity and of the recording angles of writing waves on the anisotropic Bragg diffraction properties of volume gratings was discussed. It is shown that both the ratio of the initial intensity and the incident angle of the writing waves were selective for the anisotropic Bragg diffraction efficiency of the volume gratings,while these two recording conditions were not selective for the isotropic Bragg diffraction.