LARGE OPTICAL BIREFRINGENCE IN POLY(PARA-PHENYLENE VINYLENE) FILMS MEASURED BY OPTICAL WAVE-GUIDE TECHNIQUES

We report here the observation of a large birefringence in an as-cast unoriented film of poly(p-phenylene vinylene), a material that has a large third-order non-linear optical susceptibility. A waveguide technique in TE and TM polarization is used to obtain in-plane and out-of-plane refractive indices at several wavelengths. At 633 nm the measured refractive index values are nTE = 2.085 and nTM = 1.612. No dependence of the in-plane refractive index on the direction of film spreading is found, indicating an in-plane isotropic behaviour. No anomalous dispersion of refractive index is found in the wavelength range 633-1064 nm. © 1990.