Dual-use chromophores for photorefractive and irreversible photochromic applications

Holographic experiments are performed on a series of dual-use chromophore m olecules wherein both irreversible photochromic and erasable photorefractiv e holographic gratings can be written in the same storage volume. At 675 nm , the chromophore undergoes a photochemical reaction leading to the creatio n of irreversible holographic gratings. Alternatively, at longer wavelength s, application of an electric field during grating formation allows the sto rage of erasable photorefractive holograms in the same location as previous ly stored permanent photochemical holograms. Photochemical gratings (eta > 60%) can be written in less than 1 min, whereas photorefractive gratings (e ta > 50%) can be written in less than 1 s. The photochemical gratings have a diffusion-limited dark half-life of as long as two weeks depending on the glass transition temperature of the composite. (C) 2001 Optical Society of America.