Novel approach for design of low index contrast multimode interference devices |
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Authors: | Jiangong Zhao Aijun Wen Zengji Liu and Peng Yue |
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Affiliation: | 1. State Key Laboratory on Integrated Services Networks , Xidian University , Xi'an, P.R. China zhao_jian_gong@126.com;3. State Key Laboratory on Integrated Services Networks , Xidian University , Xi'an, P.R. China |
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Abstract: | Self-imaging theory is widely accepted as a good method in designing multimode interference (MMI) couplers, but it is also true that self-imaging theory is not suitable for low-contrast structures. An improved self-imaging theory is proposed in this paper for the optimal design of low-contrast 1 × N MMI couplers. The average effective width of the MMI waveguide and the average effective propagation constant of the MMI waveguide are used in the improved self-imaging theory. An approach is given to find the average effective width. We use this approach in the optimal design of a 1?×?4 silica MMI coupler, and the results show that the improved self-imaging theory is more accurate than conventional self-imaging theory for low-contrast structures. |
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Keywords: | multimode interference couplers silica waveguides self-imaging theory |
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