All-optical switching in the near infrared with bacteriorhodopsin-coated microcavities

Photoinduced molecular transitions in bacteriorhodpsin are used to reversibly configure a micron-scale photonic component in which the optical response is resonantly enhanced. The chromophore retinal undergoes photoinduced all-trans to 13-cis conformational change, which tunes resonances in a silica microsphere coated with three bacteriorhodopsin monolayers. The tunable, all-optical resonant coupler reroutes a near-infrared beam (lambda(probe)congruent to 1311 nm) between two tapered optical fibers using a low-power (< 200 mu W) green pump (lambda(pump)=532 nm). The approach represents a bottom-up paradigm for fabrication of hybrid molecular-photonic architectures that employ self-assembled biomolecules for optical manipulation at small scales. (c) 2006 American Institute of Physics.