The D85N genetic variant of bacteriorhodopsin (BR) displays a nearly permanent lifetime of the photochromic P(490) state. We present pump–probe measurements that demonstrate this behavior. However, diffraction efficiency measurements made from holograms recorded in a hydrated D85N film show markedly different decay behavior, suggesting that a molecular diffusion process is occurring in the film. Holograms recorded with different grating frequencies display correspondingly different decay times, thus supporting this hypothesis. A thin D85N film was fabricated that was chemically cross linked, resulting in the elimination of diffusion of BR molecules within the polymer matrix. This film exhibits a grating lifetime of the order of weeks or more, thus permitting the long-term holographic storage of information.
© 1998 Optical Society of America
(090.0090) Holography : Holography
(090.2900) Holography : Optical storage materials
(210.0210) Optical data storage : Optical data storage
(210.2860) Optical data storage : Holographic and volume memories
John D. Downie, Doğan A. Timuçin, Daniel T. Smithey, and Marshall Crew, "Long holographic lifetimes in bacteriorhodopsin films," Opt. Lett. 23, 730-732 (1998)