Optical Correlation System Based on Photorefractive Polymer and Polysilane Phase Mask

Abstract Modification of the refractive index of polysilanes due to the UV-photodecomposition and its application to phase mask were investigated. From the wavelength dependence of UV-photodecomposition in the poly[methyl(phenyl) silane] (PMPS) film, the refractive index was found to be effectively lowered by eliminating phenyl side-group with shorter wavelength UV light. It was also confirmed that the phase difference information could be recordable by utilizing such refractive index changes in PMPS films. Utilizing the 4-f matched-filter architecture based on the four-wave mixing with photorefractive polymers as the optical correlator, the occurrence of large correlation signal was successfully observed only when the image written in the PMPS phase mask was coincident with the phase difference pattern on the PMPS film as a reference. This result indicates that the polysilane films with UV-photodecomposition pattern can be useful for the phase difference mask in the optical correlation system.