Bilevel mode converter between a silicon nanowire waveguide and a larger waveguide |
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Authors: | Daoxin Dai Sailing He Hon-Ki Tsang |
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Affiliation: | Centre for Opt. & Electromagn. Res., Zhejiang Univ., Hangzhou, China; |
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Abstract: | A bilevel mode converter is analyzed for providing low-loss coupling between the small fundamental mode of a silicon nanowire waveguide and the larger mode of a conventional silicon-on-insulator (SOI) rib waveguide. The bilevel converter can also be used to improve the coupling efficiency between a lensed fiber and a silicon nanowire waveguide. The mode converter consists of two tapers formed at different levels. The top taper comprises a parabolic and sine taper, which is optimized to improve the mode conversion efficiency. Numerical analyses are given by using a three-dimensional semivectorial beam propagation method. The design has good tolerance against misalignment of the two masks needed for the double etch. |
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