Processible and Thermally Stable Heterocyclic Polymers for Second-Order Nonlinear Optical Studies

Following up on our preliminary communication, we present in this paper a novel approach to synthesize processible, cross-linkable, and thermally stable heterocyclic polymers (polyoxazolidones) with nonlinear optical properties. A cross-linkable NLO chromophore was synthesized and transformed into a prepolymer, which was easy to process and cross-link. After being efficiently poled and cured, the optical-quality films exhibited good nonlinearity and thermal stability. The stable, hardened lattice resulted from the formation of the heterocyclic ring. The details of synthesizing the cross-linked (trifunctional) and un-cross-linked (difunctional) heterocyclic polymers are presented. The effects of the processing conditions on the NLO properties are described. d₃₃ coefficients of 77 and 85 pm/V at the 1.06 μm fundamental wavelength for the cross-linked and un-cross-linked polymers were obtained, respectively.