Effect of Fabry-Perot structure on electroabsorption and quadratic electro-optic modulation in the nonconjugated conductive polymer iodine-doped polyethylene terephthalate

Electroabsorption in the nonconjugated conductive polymer iodine-doped polyethylene terephthalate (PET) has been measured at 633 nm wavelength. An AC field at 4 kHz was used, and the transmission change was measured using lock-in detection. The imaginary part of the Kerr coefficient was determined from the electroabsorption data and was found to be exceptionally large, comparable to other nonconjugated conductive polymers. These large magnitudes are due to the subnanometer-sized quantum dots in these systems. At higher electric fields and /or higher doping levels, we observed enhanced modulations, hysteresis, and bistability caused by Fabry-Perot structure in the PET samples. These effects were recorded in electroabsorption and quadratic electro-optic modulation. To the best of our knowledge, this is the first time electric field-induced hysteresis / bistability has been observed for a plastic film.