Guided-wave acoustooptic tunable filters using simple coupling weighting technique

Abstract
A simple acoustooptic (AO) coupling weighting technique for sidelobe suppression that involves only variation of the width of the surface acoustic wave (SAW) slot waveguide is presented. Calculations on single-stage and multistage acoustooptic tunable filters (AOTFs) consisting of an optical channel waveguide and a SAW slot waveguide in LiNbO/sub 3/ have shown that waveguide width coupling using the Hanning weighting function provides significant improvement in sidelobe suppression. Specifically, using the Hanning function a sidelobe level of -26 dB is predicted as compared to that of -9 dB with the conventional uniform coupling. Calculated results together with the design, fabrication, and preliminary measured performance characteristics of a single-stage guide-wave AOTF in YX-LiNbO/sub 3/ substrates at the optical wavelengths of 0.6328 and 1.55 mu m are reported.<>

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