Quadratic Electro-Optic Effect and Electroabsorption in a Novel Nano-Optical Material based on the Nonconjugated Conductive Polymer, Poly(ethylenepyrrolediyl) Derivative

We report quadratic electro-optic effect and electroabsorption measurements in a novel nano-optical material based on the nonconjugated conductive polymer, iodine-doped poly(ethylenepyrrolediyl) derivative. Such effect has been recently reported in doped polyisoprene [1]. The measurement was made at 633 nm using field-induced birefringence. A modulation of 0.1{\%} was observed for a field of 0.66 V/micron (film thickness 0.3 micron). The change in refractive index, $\Delta $n, is 3.35x10$^{-4}$ and the Kerr constant is 1.2x10$^{-9 }$m/V$^{2}$ which is about 125 times that of nitrobenzene. Modulation due to electroabsorption was 0.05{\%}. The exceptionally large electro-optic effect is most likely due to the specific structure and quantum confinement within a nanometer volume. In contrast, nonlinearity in a conjugated polymer is known to decrease upon iodine doping. [1] Thakur, Swamy and Titus, \textit{Macromolecules}, Vol.37, 2677, (2004).