Holographic storage in conjugated-polymer composites

We report on holographic storage with relatively high diffraction efficiencies in films (2 μm to 20 μm thick) of conjugated polymer/glass and conjugated polymer/polymer composites with emphasis on the former. An index of refraction change (Formula presented) as high as (Formula presented) was obtained. The grating formation was attributed primarily to the photochromic effect. However, the anomalous large two-beam coupling that was observed in these materials cannot be explained by a photochromic mechanism. This, together with the small nonlinear electro-optic coefficient (Formula presented) may suggest that a weak photorefractive process also contributes to the hologram formation in these materials. Holograms written on these conjugated polymer composite films are stable in the dark for (at least) one year.