High-gain photorefractive polymers

We report on the photorefractive properties of polymer composites based on the dye 2, N, Ndihexylamino-7-dicyanomethylidenyl-3, 4, 5, 6, 10-pentahydronaphthalene (DHADC-MPN). At 633 nm and with 2,4,7-trinitrofluorenone as a sensitizer, the polyvinylcarbazole-based composites show complete internal diffraction at applied electric fields as low as E_π/2 = 30 V/μm. The sensitivity of the composite could be extended into the infrared by using (2,4,7-trinitro-9-fluorenylidene)malonitrile as a sensitizer, and at 830 nm complete internal diffraction occurred at an applied field of E_π/2 = 59 V/μm. Finally, by using DHADC-MPN as a trifunctional dopant in an inert matrix, we have achieved a dynamic range of Δn = 0.0085 and a net two-beam coupling gain of Γ = 202 cm^-1 at an applied field of 50 V/μm and at 633 nm. The composites are thermally stable or have shelf lifetimes of at least several years at room temperature.