Quadratic Electro-optic Measurements in Nonconjugated Conductive Polymers, iodine-doped Polyisoprene and Poly($\beta $-pinene) at 1.55$\mu $m

Exceptionally large near-resonant (at 633nm) quadratic electro-optic effects in nonconjugated conductive polymers, iodine-doped poly($\beta $-pinene) and 1,4-cis-polyisoprene have been previously reported. In this report, we discuss the quadratic electro-optic effects in these polymers at 1.55$\mu $m. The measurements were made using the field-induced birefringence technique. A modulation depth of about 0.1{\%} was observed for a 1 $\mu $m thick sample of doped poly($\beta $-pinene) at an applied field of 1V/$\mu $m. The Kerr coefficient as determined was about 1.6$\times $10$^{-10}$ m/V$^{2}$. For polyisoprene samples the modulation was slightly smaller. These exceptionally large Kerr coefficients at a technologically important wavelength make these polymers promising for guided-wave applications in electro-optics. Techniques for longer-term stability of the samples have been established. The large optical nonlinearities as observed have been attributed to the sub-nanometer confinement of these charge-transfer systems