Nicolai N. Vsevolodov

Photoinduced anisotropy in bio-chrom films

Abstract The photoanisotropic properties of Bio-chrom films consisting of a photochemically active purple membrane of Halobacterium halobium dispersed in a polymer matrix are studied. A model of the material based on a reversible anisotropic bleaching of the photosensitive molecules (bacteriorodopsin) is discussed. The main holographic characteristics of the real time holograms recorded in the Bio-chrom films are given.

Retinal—protein complexes as optoelectronic components

Naturally occurring retinal-protein complexes (RPCs) have recently received much attention with regard to their potential use as light-sensitive elements for optical recording. The best-known RPC is bacteriorhodopsin (BR), a photosensitive protein from the membrane of extreme halophilic bacteria, which has been studied in great detail. The remarkably robust nature of BR, coupled with its ability to reversibly change color upon illumination and its high cyclicity of ground-to-photoinduced state transitions, makes BR a promising material for optical information processing.

Optical properties of Triton X-100-treated purple membranes embedded in gelatin films☆

Abstract The purple membrane (PM) of the microorganism Halobacterium salinarium contains a hexagonally packed monolayer of the light-sensitive protein, bacteriorhodopsin (BR). The optical characteristics of gelatin-immobilized PMs depend strongly on the chemical environment of the PMs in the matrix. Here we present photoinduced absorptive and holographic characteristics of gelatin-embedded PMs solubilized with the non-ionic detergent, Triton X-100. The BR/detergent interaction was shown to slow the M-to-initial state transition of the photocycle and to increase the photosensitivity of the BR films. The lifetime of the holographic grating in Triton X-100-treated BR films was 2–3 times greater, when compared to the unmodified sample. Holographic grating growth times in BR films were shown to change depending on the extent of solubilization. The measured holographic sensitivity appeared to maximize in the range of Triton X-100/BR molar ratios from 15:1 to 25:1. The possible advantages of solubilized PM films as they are applied to optoelectronic devices are discussed.

Holographic properties of Triton X-100-treated bacteriorhodopsin embedded in gelatin films

Bacteriorhodopsin (b) thin films have been fabricated with varying amounts of the detergent Triton X-100 to measure the effect of this additive on the holographic performance of these thin films. Holographic spectroscopy is used to measure the effect of these detergents on the overall diffraction efficiency as well as on the phase and amplitude components of the overall signal. The diffracted rise and decay kinetics of these materials will also be presented as a function of varying detergent concentration. This research also studied the effect of this additive on the absorptive properties of bR-based thin films. Comparisons of the two complimentary sets of data are drawn.

High-capacity optical spatial switch based on reversible holograms

This paper discusses the architecture of an N X N optical spatial switch in which independent and arbitrary switching is realized using diffraction of light beams by a microhologram array (MA) programmed by two 1 X N acousto-optical elements. It is shown that a bacteriorhodopsin film can be used as a recording medium for MA. The throughput of each channel, being up to several Gbit/s the capacity of such a switch, can reach 104 X 104 channels, the time of an arbitrary switching being not more than 100 ms. Experimental results are given proving the possibility of implementing a switch having said characteristics.

Some methods for irreversible write-once recording in 'biochrom' films

Summary form only given. The data-storage capabilities of the photochromic material biochrom, a film based on bacteriorhodopsin (BR) embedded into a polymeric matrix, are described. The material is capable of recording optical information (upon exposure to light) with constant and reversible storage at high spatial resolution (>5*10/sup 3/ lines/mm), photosensitivity up to 10/sup -3/ J/cm/sup 2/, and high cycling (10/sup 4/ cycles). Various types of recording (holographical, polarizable, by bits, etc.) are possible. Image recording is performed by yellow light and its erasure by blue light.<<ETX>>

Application of polymer films based on bacteriorhodopsin and its analogs for low-light-level imaging systems

In recent years polymer films based on bacteriorhodopsin (BR) have attracted a lot of attention in the area of optical imaging systems. The high photosensitivity of these films allows the processing of low-power optical signals (several mW/cm2 CW gas laser irradiation). Spatial resolution does not fall below 5000 lines/mm, photoresponse time is 50 microsecond(s) and images can be recorded and erased over million cycles. Polymer film with BR combine a dynamic recording with optical image processing. The characteristics of anisotropically-saturating nonlinearity of polymer films with BR allow a suppression of the background with greater intensity than usable signal intensity of be performed. Low saturation intensity of the polymer films with BR allows the operation of the polarization of low-intensity signals to be realized. Nonlinear photoresponse of the high photosensitivity BR genetic variant Asp96-Glu is studied in this work too. We hope that the polymer films based on BR and its analogs will find potential use precisely in the medical low- light-level imaging systems.

Contrast enhancement and phase conjugation low-power optical signal in dynamic recording material based on bacteriorhodopsin

Polymer films with fragments of the purple membranes containing protein bacteriorhodopsin (BR) have been used for the real-time optical information processing of low-power (several milliwatt) cw gas laser signals. The nonlinear recording media with BR have a potential in microscopic techniques for in-vivo diagnosis of the crystalline lens.

Application of the dynamic holography for study of light adaptation process of the purple membranes

The light adaptation of the purple membranes in polymeric environment under laser irradiation has been researched by means of the dynamic holographic method. Holographic parameters stability of the photosensitive materials based on bacteriorhodopsin (BR) has been studied.