Study On The High-speed Guided-wave Acousto-optic Modulator

High-speed guided-wave acousto-optic modulator is one of the best switching devices because of its advantages, such as high speed, compact size, low insertion loss, excellent design flexibility, high mechanical stability, low driver power requirement, good integration, etc. It also can be used in the high-speed optical communication field.In this paper, some theoretic and laboratorial research on the high-speed guided-wave acousto-optic modulator has been done. The acoustical waveguide and optical waveguide are studied in theory. The first step pilot production of the new-style modulator is finished. Some experimental researches about testing the modulator are also included in the paper.The main contents of the paper are listed as follows:1. The development and trends of guided-wave acousto-optic modulator in China and overseas have been reviewed and introduced.2. The basic theories about guided-wave acousto-optic modulator have been researched, including the theories about surface acoustic wave (SAW), guided wave in the optical waveguide, acousto-optic effect of surface wave, the principle of waveguide acousto-optic modulation, and so on.3. By using the boundary and decoupled qualifications, the coupled wave and the piezoelectric equations are solved. Then the optimum thickness of the acoustical waveguide can be designed, considering both the wave velocity of the SAW and the electromechanical coupling coefficient which have been solved. The results are simulated by Matlab.4. Beam Propagation Method (BPM) is chosen to analyze the optical waveguide. The optical waveguide of the modulator, which is designed before, is simulated and analyzed by the software OptiBPM and the results point out the problems existing in the design. The three main factors which influence the performance of the taper waveguide in design are analyzed. Based on the analytic results, the taper waveguide is re-designed and the optimum design is gained.5. The pilot production of the optical waveguide, which is the first step of completing the high-speed guided-wave acousto-optic modulator, has been finished. Then we conduct the experimental research on testing the optical waveguide. According to the results, the ideas for improving the modulator are provided.