ABSTRACT
The principle of all-optical logical operations utilizing the unique nonlinear optical properties of a protein was demonstrated by a logic gate constructed from an integrated optical Mach-Zehnder interferometer as a passive structure, covered by a bacteriorhodopsin (bR) adlayer as the active element. Logical operations were based on a reversible change of the refractive index of the bR adlayer over one or both arms of the interferometer. Depending on the operating point of the interferometer, we demonstrated binary and ternary logical modes of operation. Using an ultrafast transition of the bR photocycle (BR-K), we achieved high-speed (nanosecond) logical switching. This is the fastest operation of a protein-based integrated optical logic gate that has been demonstrated so far. The results are expected to have important implications for finding novel, alternative solutions in all-optical data processing research.
Subject(s)
Bacteriorhodopsins/chemistry , Interferometry/instrumentation , Optics and Photonics/instrumentation , Refractometry/instrumentation , Equipment DesignABSTRACT
Several inorganic and organic materials have been suggested for utilization as nonlinear optical material performing light-controlled active functions in integrated optical circuits, however, none of them is considered to be the optimal solution. Here we present the first demonstration of a subpicosecond photonic switch by an alternative approach, where the active role is performed by a material of biological origin: the chromoprotein bacteriorhodopsin, via its ultrafast BR->K and BR->I transitions. The results may serve as a basis for the future realization of protein-based integrated optical devices that can eventually lead to a conceptual revolution in the development of telecommunications technologies.
Subject(s)
Bacteriorhodopsins/chemistry , Bacteriorhodopsins/radiation effects , Models, Theoretical , Nonlinear Dynamics , Optical Devices , Photochemistry/methods , Photons , Computer Simulation , Equipment Design , TelecommunicationsABSTRACT
According to our earlier pioneering study, a dry film containing native bacteriorhodopsin (bR) shows unique nonlinear optical properties (refractive index change, controllable by light of different colors, greater than 2 x 10(-3)) that are in many respects superior to those of the materials presently applied in integrated optics. Here, we report on the first integrated optical application based on a miniature Mach-Zehnder interferometer (see Figs. 1 and 2) demonstrating a real switching effect by bR (efficiency higher than 90%) due to the M-state. Our results also imply that the refractive index change of the K-state (9 x 10(-4)) is high enough for fast switching.
Subject(s)
Bacteriorhodopsins/chemistry , Bacteriorhodopsins/radiation effects , Electronics , Microscopy, Interference/instrumentation , Microscopy, Interference/methods , Optics and Photonics , PhotochemistryABSTRACT
A simplified Brownian dynamics model and the corresponding software implementation have been developed for the simulation of electrolyte dynamics on the mesoscopic scale. In addition to direct control simulations, the model system has been verified by a quantitative comparison with the Debye-Hückel theory. As a first application, the model was used to simulate ionic relaxation processes following abrupt intramembrane charge rearrangements in the case of a disk shaped membrane. In addition to its general implications, the obtained properties of the relaxation kinetics confirm the assumptions of the theory of the so-called suspension method, a technique capable of tracing molecular charge motions of membrane proteins in three dimensions.
