Study On The Absorption And Modulated Properties And Its Applications Of Nanobiological Material-Bacteriorhodopsin

Bacteriorhodopsin (BR) is the sole protein present in the purple membrane of Halobacterium halobium. The biological function of the BR is acted as a light-driven proton pump. The BR molecule has many good properties such as excellent thermal, chemical and photochemical stability, very high spatial resolution (-5000 lines/mm), broad-spectrum scope (400-700nm), high photosensitivity (-10mJ/cm2), good quantum efficiency (-65%), fast response (-50μs) and high contrast etc. These attractive properties made it a generally interested light-sensitive media for optical information processing. Now the biochemical and biophysical knowledge on the BR makes it possible to modify some optical properties of the BR in order to make it more useful for many optical processing applications. All these make the BR adapt to use more widely in the field of optical information processing. With the nanometer technology and biotechnology developing, the scientists think the BR can be taken for a kind of nanometer scale optical biology material. In the future, the BR material will be used to develop nano-protein component and make an impact on the information field. In this article, the composition, structure, fundamental property and history and current status of the research of the BR is summarized. Its function properties are described also and its important optical features are analyzed too. The photoabsorption properties of three kinds of BR molecule films (the wild-type BR, the chemical enhanced BR, the gene-variant BR) are investigated by measuring their absorption spectrum. Using the gene-variant BR film as a light-modulator, by the experiment of write-readout image and the analysis of image contrast, the light-modulated property of the modulator is studied. The relationship between wavelength of the modulated light and response time of the modulator is discussed emphatically. It has been found in the experiment that a reverse of image appeared in the wavelength range between 550nm to 620nm at which the enhancement of absorption of the probe beam appeared after a while of the probe time or readout time delaying. With the joint action of the Q-switched pulse laser of 532nm and continuous probe light of different wavelengths, fast photoresponse characteristic of photocycle of a wild-type BR film (WT3) and photoabsorption characteristic of different intermediary in the photocycle are analyzedand discussed. The optical switch action in the microsecond scale is observed in the experiment. An optically addressed spatial light modulator (OA-SLM) made of BRD96N and based on its good nonlinear optical characteristics is presented. An experiment study on the mutual conversion of coherent-to-incoherent image is carried out, and the mutual modulation of two spatial light beams can be realized base on the gene-variant BR films.