Electro-optic effects in two tolane side-chain nonlinear-optical polymers: Comparison between measured coefficients and second-harmonic generation

The electro-optic coefficients for the chromophore nitroamino tolane [NAT(C2H5)-ø-C≡ C-ø-NO2] attached to either a poly(methyl methacrylate) or an epoxy polymer have been measured by three different techniques: attenuated total reflection, ellipsometric reflection, and Mach-Zehnder interferometry. All the results for r33 and r13 were consistent and in agreement. A comparison of these experimental methods is given. The ratios between the electro-optic coefficients and the relationships between the coefficients and the second-harmonic components give additional information about these nonlinear-optical polymers. Interestingly, it was found that the observed electro-optic coefficients increased after the samples had aged a few months. © 1993 Optical Society of America.