MODIFIED POLYIMIDE SIDE-CHAIN POLYMERS FOR ELECTROOPTICS

New modified polyimide polymers with pendent side group nonlinear opti cal (NLO) azo chromophores and moderate to high glass transition tempe ratures (140-degrees-C < T(g) < 190-degrees-C) have been prepared. Cor ona poled films of these polymers possess large nonlinear optical susc eptibilities of d31 = 23 pm/V and electrooptic (EO) coefficients of r1 3 = 6.5 pm/V at a wavelength of lambda = 1.3 mum. The structural prope rties (glass transition, molecular weight, chromophore density) and op tical properties (refractive index, optical nonlinearity) of these pol yimides can easily be varied to fulfill the requirements of potential electrooptic devices. Due to the relatively high glass transition temp eratures of these polymers, long-term stability of the optical nonline arity of typically one to hundreds of years at operating temperatures of 80-100-degrees-C is predicted from accelerated time-temperature mea surements. Using a development of a phenomenological theory of the gla ss transition, a normalized relaxation law is proposed with (T(g) - T) /T as the relevant scaling parameter.