Synthesis

characterization and nonlinear optical properties of isocyanate crosslinked epoxy-based second—order nonlinear optical (NLO) polymers were studied in this paper．The epoxy-based second-order NLO polymer (BPAN-lA-NT) was synthesized through the coupling reaction between p-nitrophenyl diazonium salt and an epoxy-based precursor polymer

which was prepared by the polycondensation of diglycidyl ether of bisphenol-A and aniline Bi-component (BPAN-lA-NT/M2OS) thin films were prepared by spin-coating from the solution of BPAN-lA-NT mixed with certain amount of a cross linking agent M2OS (MDI based isocyanate)．The epoxy-based second-order NLO polymer BPAN-lA-NT could be crosslinked by the reaction with isocyanate during the poling process．A high second-order nonlinear optical coefficient of 105.2 pm/v at 1.064 μm was obtained for the bi-component films after corona poling．Moreover

thermal stability measurement of poled BPAN-lA-NT/M20S film showed good dipole orientation stability at high temperature

retaining above 80％ of the initial d33 value at 200℃．At the sametime for the single component BPAN-lA-NT thin film its d33 value was 33.2 pm/v only and the d33 value decreased obviously when the temperature was higher than 120℃．