Resolving response speed dependencies of photorefractive polymer materials

Summary form only given. Internal diffraction efficiencies of 90% are routinely observed in our crystallization-resistant 1-(2´-ethylhexyloxy)-2,5-dimethyl-4-(4-nitrophenylazo)benzene (EHDNPB): poly(N-vinylcarbazole) (PVK): 2,4,7-trinitro-9-fluorenone (TNF) polymer composites. The device longevity is >10 mo. For many of these applications, however, the speed of response remains a limitation and is the subject of study using time-resolved degenerate four-wave mixing (DFWM), Mach-Zehnder interferometry, and time-resolved transmission ellipsometry. The composites studied consisted of a host charge-transporting PVK:TNF polymer network and a dopant azo dye, EHDNPB, which is added to provide an electro-optic response. The polymer material was sandwiched between two conducting plates to allow an AC or DC electric poling field to be applied. A photorefractive grating was written into the devices by DFWM, and the photorefractive response speeds of the composites were investigated.