EO polymer at cryogenic temperatures

Electro-optic (EO) properties at 7 K of a guest-host type nonlinear poled polymer system consisting of AJLZ53 chromophores in an amorphous polycarbonate host are reported for the first time. A modi-fied attenuated total reflection method that takes into account multilayer structure is used to accurately characterise linear and nonlinear optical properties. At the telecommunication wavelength of 1550 nm, <10% drop of the EO coefficient r₃₃ at 7 K is observed compared with that at 300 K, while n³r₃₃ only decreases <5% because of increased anisotropic indices of refraction at low temperatures. This decrease of the r₃₃ at 7 K indicates that the EO activity of nonlinear polymers at room temperatures is not of pure electronic origin because of vibrational mode contributions to the first-order hyperpolarisability.