用于SOI脊形波导的模式匹配器的设计

Design of Mode Transformers for Rib Waveguides Based on Silicon-on-insulator

引入4种不同形状的模式匹配器,提高了SOI(Silicon On Insulator)脊形波导和单模光纤(SMF)的耦合效率。用三维束传播法(BPM)和重叠积分方法对这4种模式匹配器进行了结构设计和性能分析。结果表明,这4种模式匹配器对提高耦合效率的能力几乎相同;经过结构优化后,模式匹配器的耦合效率约提高了0 5dB;当模式匹配器长度大于800μm时,耦合效率几乎不随长度变化,因此模式匹配器长度取值应大于800μm。最后分析了封装对准中的对准精度要求。若要求附加损耗小于0 3dB,对准偏差须小于1μm。

The coupling efficiency between a rib waveguide based silicononinsulator(SOI) and a singlemode fiber(SMF) was improved by using an optimally designed mode transformer.A threedimensional semivectorial beam propagation method(BPM) and an overlapped integral method were used for the numerical simulation of four kinds of mode transformers with different shapes.It is shown that the capabilities of the four kinds of mode transformers to improve the coupling efficiency are almost the same.The coupling efficiency is improved by about 0.5 dB when an optimal mode transformer is used.The coupling efficiency is improved by about 0.5 dB when an optimal mode transformer is used.The coupling efficiency is almost constant when the length of the mode transformer is larger than 800 μm.Thus the length of the mode transformer should be larger than 800 μm.The tolerance for the alignments of a SOI rib waveguide and a SMF is also analyzed.For an allowable excess loss of 0.3 dB,the deviation of the alignment has to be smaller than 1 μm.