All-optical switching with bacteriorhodopsin protein coated microcavities and its application to low power computing circuits

Abstract

We show all-optical switching of an input infrared laser beam at 1310 nm by controlling the photoinduced retinal isomerization to tune the resonances in a silica microsphere coated with three bacteriorhodopsin ͑BR͒ protein monolayers. The all-optical tunable resonant coupler reroutes the infrared beam between two tapered fibers in 50 s using a low power ͑Ͻ200 W͒ green ͑532 nm͒ and blue ͑405 nm͒ pump beams. The basic switching configuration has been used to design all-optical computing circuits, namely, half and full adder/subtractor, de-multiplexer, multiplexer, and an arithmetic unit. The design requires 2 n − 1 switches to realize n bit computation. The designs combine the exceptional sensitivities of BR and high-Q microcavities and the versatile tree architecture for realizing low power circuits and networks ͑approximately mW power budget͒. The combined advantages of high Q-factor, tunability, compactness, and low power control signals, with the flexibility of cascading switches to form circuits, and reversibility and reconfigurability to realize arithmetic and logic functions, makes the designs promising for practical applications. The designs are general and can be implemented ͑i͒ in both fiber-optic and integrated optic formats, ͑ii͒ with any other coated photosensitive material, or ͑iii͒ any externally controlled microresonator switch.

Whispering gallery mode sensors

“…The bacteriorhodopsin-coated WGM sensor was then used to demonstrate the detection of photoinduced conformational changes, monitoring TE and TM WGM shifts in parallel (see Fig. 28), as well as to demonstrate all-optical switching [192,323,324]. More recently, membrane nanodiscs as a model system for natural membranes were attached to silicon ring resonators.…”

Bio-nano hybrid materials based on bacteriorhodopsin: Potential applications and future strategies

“…This rapid isomerization of retinal in combination with well-defined conformational changes in bR during the photocycle leads to the transport of a proton from the cytoplasmic to the extracellular side of the membrane [19]. The interesting point about the photocycle is that all the intermediate states are able to be photo-chemically switched back to the bR 568 state by shining light at a wavelength that corresponds to the absorption peak of the respective intermediates [20,21].…”

All-optical logic gates based on photoinduced anisotropy of bacteriorhodopsin film

“…Various methods of optical logic operation based on BR films have been proposed. For instance, the XOR, OR and AND logic gates have been realized using photorefractive two-wave mixing [12,13], 11 kinds of all-optical logic gates based on the nonlinear intensity-induced excited state absorption of the K, L, M, N, and O states in the BR photocycle have been demonstrated [14,15], all-optical logic gates have been designed with a BR film based on complementary suppression-modulated transmission [16,17], and all-optical reversible gates, namely, Feynman, Toffoli, Peres, and Feynman double gates, based on optically controlled BR protein-coated microresonators have been proposed [18,19].…”