Birefringence oscillations in an organic guest-host system

Abstract

The nonlinear dye N, N-Dihexyl-4 amino-4-nitrostilbene (DHANS) was incorporated in the polymer matrix of poly(α-methyl-styrene) (Pα MS). Dye concentrations between 1 and 10 weight % were investigated. Bulk samples of DHANS/Pα MS were prepared with a residual solvent content of 5 wt% in an optical cell between electrodes. Solid samples of high viscosity were obtained. Electrooptic measurements were perfomed for DC electric fields up to 30 RV/cm with a HeNe laser. Besides the usual Pockels- and Kerreffect we observed birefringence oscillations. For this experiment the Pα MS matrix has to be in the glass transition region. Parallel to the birefringence oscillations peaks in the DC current were measured. Frequency and amplitude of the oscillations depend on the external electric field. We suggest an interpretation of local discharging due to the anisotropic electrical conductivity of the dye molecules. © 1990 SPIE.