Applications of bacteriorhodopsin for optical data storage and processing

Hologram recording and reconstruction using differing wavelengths often provides a means, with suitable recording materials such as bacteriorhodopsin (BR), for reducing the problem of destructive readout. BR is generally insensitive to light wavelengths exceeding 700 nm. Upon exposure to light BR molecules are photochromically excited, undergoing a complex photocycle characterized by several spectroscopically distinct intermediates. One of these excited states, the M-state features a relatively long lifetime (from milliseconds to hundreds of seconds) and is fully photoreversible, making it suitable for a wide range of optical applications. We have used this bistable nature of BR to record and reconstruct holograms, using a real time scheme in which we perpetually record holograms by blue light and simultaneously reconstruct it by red (M-type holograms). In particular, we have investigated a geometry where both recording and readout beams are highly divergent spherical beams which arise from point sources