Design of Tapered SAW Waveguide for Wavelength-Selective Optical Switches Using Weighted Acoustooptic Interaction

摘要

Optical wavelength-selectivity in optical switches using waveguide-type collinear acoustooptic interaction is studied from the viewpoint of sidelobe suppression. It is found that the sidelobe level can be reduced from -9.3 dB to -20 dB by weighting the coupling coefficient over the interaction region. A method to realize the sidelobe suppression by means of modifying the surface acoustic wave (SAW) waveguide is proposed and theoretically analyzed to design the SAW waveguide. A sidelobe suppression at -20 dB is realized with a SAW waveguide of a dense-flint glass strip whose width and thickness are varied accordingly in the ranges of 700 to 26 μm, and 0.4 to 1.0 μm, respectively, on a Y-X LiNbO{sub}3 substrate.