Protein based all-optical switching

Principal Investigator: András Dér and Pál Ormos
This project is part of the NATO Science for Peace Project 974262

Recently, we have reported the first integrated optical application based on a miniature Mach-Zehnder interferometer demonstrating a real switching effect by bacteriorhodopsin (efficiency higher than 90%) due to the M-state. Our results also imply that the refractive index change of the K state (9x10-4) is high enough for fast switching.

The waveguide structure was created by photopolymerisation

1. Layering a coating of the optical adhesive to the surface by spincoating. 2. Writing of the interferometer structure by focused 410 nm laser light. 3. The unexposed part of the optical adhesive is washed off. 4. Cleaving of the glass plate in order to achieve proper end faces for the     waveguide. Click the image to view an animation showing how the structure is created.

Scanning electron micrograph images of the Mach-Zehnder interferometer:
Side view of the Y-branch (right), cross-sectional view of a cleaved single strip (left).




The ready-to-use device with the purple bR adlayer on the middle part and with singlemode optical fibers fixed at the two cleaved ends.




A schematic representation of the experimental setup.




The figures show the all-optical switching effect by the M-Z interferometer covered with a bR film as an adlayer (left). Sinusoidal modulation of the transmitted red light as a function of exciting light intensity (right). Guided light: diode laser at 670 nm, exciting light: Ar-ion laser at 488 nm.

Reference:
Der A., Valkai S., Fabian L., Ormos P., Ramsden J.J., Wolff E.K. Integrated Optical Switching Based on the Protein Bacteriorhodopsin Photochem Photobiol. 83, 1 (2007).