Determination of the electro-optical coefficient r₃₃ and refractive index of para-substituted poly(γ-benzyl-l-glutamate) derivatives

The electro-optical coefficient r₃₃ and refractive index of films of poly(γ-benzyl-l-glutamate) and the p-nitro, p-fluoro and p-trifluoromethyl derivatives were determined as a way to assess the non-linear optical behaviour of these organic polymers. The p-fluoro-γ-benzyl and p-trifluoromethyl-γ-benzyl ester polymers are new materials synthesized for this study. The electro-optical coefficient r₃₃ = 5.2 × 10^-2 pm V^-1 for the unsubstituted polymer, 13.9 × 10^-2 pm V^-1 for the p-nitro polymer, 3.0 × 10² pm V^-1 for the p-fluoro polymer, and 1.6 × 10^-2 pm V^-1 for the p-trifluoromethyl polymer. The refractive indices, at a wavelength of 488 nm, of films of the polymer were determined to be 1.60, 1.61, 1.59, and 1.70, respectively, for the unsubstituted polymer and the p-nitro, p-fluoro, and p-trifluoromethyl derivatives. The frequency dependence of the dielectric constant, from 10 kHz to 4 MHz, for each of the polymer films was also determined. The waveguiding and other properties of each of the polymers were assessed in terms of the polymer structure.