The coupling and superposition behavior of higher-order diffraction image based on photorefractive nematic liquid crystal materials

We report some photorefractive higher-order diffraction phenomena of two kinds of photorefractive nematic liquid crystal materials. In the experiment, we observed the superposition of higher-order diffraction images, the coupling of higher-order diffraction lights, and the coupling between higher-order diffraction lights and incident beams. The observed behavior suggests the complexity of the coupling process. The properties of higher-order diffraction images are discussed theoretically, which are in good agreement with experimental results.