Novel Photorefractive Materials Based on Crosspolymerizable Poly(imide-co-diacetylene)s for Optical Signal Processing

Real time thin film holographic elements are crucial components in optical signal processing technologies. There is a need for the development of materials to record both permanent and re-configurable holograms. Polymeric photorefractive (PR) materials show promise as inexpensive holographic media. MTI proposes to develop a new class of polymeric PR materials. These are thermally crosspolymerizable poly(imide-co-diacetylene) derivatives with highly nonlinear optical (NLO) chromophores in the side chain. Diacetylene blocks in this type of copolymer are known to crosspolymerize, forming a highly conjugated polydiacetylene structure with large charge carrier mobilities and high photoconductivity. UV and g radiation may also be utilized for diacetylene crosspolymerization. The imide blocks will be functionalized with thiophene based NLO chromophores with large 'uB' values. High photoconductivity and large mobility, in conjunction with large, stable NLO properties, would result in a fast and efficient PR response in these materials. Synthesized polymers will be poled and thermally crosspolymerized in thin and thick films, characterized for linear and NLO properties, photoconductivity, and charge carrier mobility. Two-beam-coupling and degenerate four-wave-mixing experiments will be performed to evaluate PR properties. These materials are expected to surpass existing polymeric PRs in speed, stability and sensitivity. The proposed polymeric PR materials would yield an inexpensive and efficient holographic recording medium. Such materials have applications in optical signal processing, high density optical data storage, and holographic optical interconnects. Additionally, such materials are suited for devices in industrial control and automation, based on real-time optical interferometry.