Nanometer-Au-particle-enhanced photorefractivity in a polymer composite

Doped with nanometer Au particles, a low-T-g photorefractive polymer composite, poly(N-vinylcarbazole):2,4,7-trinitro-9-fluorenone:4-(dicyanovinyl-N,N-diethylaniline), exhibited an effective enhancement on its photorefractivity. Measurements on two-beam coupling (TBC) as well as four-wave mixing were carried out at 633 nm wavelength. At an applied electric field of 118 V/mu m, TBC coefficient as high as 206 cm(-1) was obtained in the sample doped with Au particles, while only 152 cm(-1) in the sample without Au particles. The measurements on the effective electro-optic coefficient and the photorefractive phase shift for two samples with and without doping Au particles were performed, respectively. The observations of distinct difference on the photorefractive phase shift and no difference on the effective electro-optic coefficient implied that enhancement on the photorefractivity was due to the increment of the density of the effective trap center by doping Au particles. (C) 1999 American Institute of Physics. [S0003-6951(99)00947-X].