Photoinduced anisotropy and dynamic polarization holography on bacteriorhodopsin films for optical information processing

Bacteriorhodopsin (BR), a photoreceptor protein possesses a photochemical cycle of several distinct intermediates; all of them are photoactive. The BR molecules both in the initial form of the photocycle, bR570 (absorption maximum around 570 rim) and longest-lived (in films) intermediate M412 (absorption maximum at 412 run) possess anisotropic absorption. Under the action of linearly polarized light, the reversible anisotropic photoselection of BR molecules takes place. In the present work, the potentiality for the use of photoinduced anisotropy in the BR-films based on both bR570 and M412 for the logical image processing is demonstrated. The dynamic polarization holography recording based on anisotropic photoselection mechanism allows one to increase a storage density and decrease the information erasure during the read-out procedure. A comparison of the experimental dependence of the relation between diffraction efficiencies of the intensity and polarization gratings on the recording intensity with calculated one is a very sensitive technique to study the intensity-dependent recovery time. It is shown that average recovery time in bR570 decreases with increasing the He-Ne laser recording intensity. Hence, a. data storage time can be controlled by recording light intensity.