PHOTOREFRACTIVE POLYMERS BASED ON DUAL-FUNCTION DOPANTS

A new class of photorefractive polymeric materials is described on the basis of inert polymer binders doped with a single small molecule spe cies which has the dual function of providing both charge transport an d optical nonlinearity, in order to maximize the volume fraction of bo th functionalities. A variety of compositions are investigated, using combinations of seven different dual-function dopants, four different polymer binders, and two different sensitizing agents. The diffraction efficiency and characteristic response times of the observed gratings depend on the identity of the dual-function dopant as well as the bin der polymer. In contrast to previous photorefractive polymers, mobilit y plays an important role in determining the response times of these m aterials The increased concentration of the nonlinear optical chromoph ore which can be achieved leads to improved performance. Diffraction e fficiencies as high as 7%, grating growth times of 0.43 s, and net two -beam coupling gain coefficients of 34 cm(-1) are observed in the poly mer PMMA (poly(methyl methacrylate)):DTNBI yl-2,2-tetramthylene-5-nitr obenzimidazoline):C-60.