Photorefractive Effect in a Polymer Molecularly Doped with Low-Molecular-Weight Compounds

Abstract

The photorefractive effect is observed in poly (methylmethacrylate) molecularly doped with three types of low-molecular-weight compounds, carrier transport (CTM), carrier generation (CGM) and nonlinear optical (NLO) materials. With these materials as dopants, the polymer exhibits both photoconductivity and the electro-optic (EO) effect under DC electric fields. The EO coefficient r33 is found to be linearly dependent on applied fields because of the lower glass-transition temperature (T g). In two-beam coupling and diffraction measurements, refraction gratings are written in the polymer. A phase shift of 90° between a refraction grating and a fringe pattern with applied fields proves the existence of the photorefractive effect, which is distinguished from heating effects. A maximum diffraction efficiency η of 4×10-6 is obtained in the photorefractive polymers.