Nanooptics and photonics

Nonlinearly-optical adjustment of bacteriorhodopsin molecule nanostructure for real-time optical switching
Korchemskaya E.1,2, Stepanchikov D.3, Savchuk A.1
1 International Center “Institute of Applied Optics” of the NAS of Ukraine. Kudryavskaya St., 10g, Kiev-01054, Ukraine.
E-mail: elkorch@hotmail.com
2 Institute of Physics of the NAS of Ukraine. Prospect Nauki, 46, Kyiv-03039, Ukraine. 
3 Zhytomir State University, Velyka Berdychivska St., 40, Zhytomir-10008, Ukraine. 

Bacteriorhodopsin (BR) molecules arranged at 120 degrees into trimers forming a two-dimensional hexagonal crystalline lattice with a space of 62  in the purple membrane fragment of the microorganism Halobacterium salinarium is promising for utilization in nanobiophotodevices [1,2]. Upon absorbing visual light, a BR molecule transports a proton during the photochemical cycle. The initial photocycle form of wild type BR, B, has an absorption peak at 570 nm, and the shortwavelength-absorbing intermediate M has an absorption peak at 412 nm. All photocycle intermediates are photoactive and have anisotropic absorption [3]. The time of B↔M transition is about 50 s. 
We have shown that both the light intensity variation of low-power cw He-Ne (He-Cd) laser beams and the angle variation between the polarization directions of He-Ne and He-Cd laser beams at the constant light intensity of these beams can be used for adjustment of a transformation to the intermediate M of one, two or three molecules in BR trimers. A real-time optical polarized switch based on transformations in the BR trimer is proposed.

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