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Integrated Optical Switching Based on the Protein Bacteriorhodopsin


  • This paper is part of the Proceedings of the 12th International Conference on Retinal Proteins held at Awaji Island, Hyogo, Japan on 4–8 June 2006.

*email: (Elmar K. Wolff)


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 × 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 × 10−4) is high enough for fast switching.

Figure 1.

Figure 1.

 Electron micrograph images of the photopolymeric Mach–Zehnder interferometer (two oppositely joined Y-junctions, symmetrically dividing and rejoining the beams, respectively). (a) Cross-sectional view of a single strip. (b) Side view of a single strip. (c) View of a Y-branch. (d) View of the whole Mach–Zehnder structure (shaded inside).

Figure 2.

Figure 2.

 Photographs of the Mach–Zehnder interferometer guiding green light (488 nm line of an Ar-ion laser).