多模干涉耦合器中重叠像相干相消现象分析

根据多模干涉耦合器的自映像原理和重叠成像的规律, 首次提出多模干涉耦合器中存在重叠像相干相消现象, 推导了重叠像相干相消现象出现的条件. 在此基础上, 对对称干涉和成对干涉两种特殊重叠成像做出解释, 得出对称干涉和成对干涉成像个数及成像位置的表达式. 用实例证明了重叠像相干相消现象并不只存在于成对干涉和对称干涉两种特殊情况, 并总结了重叠像相干相消随位置数变化的规律. 用导模传输分析法验证了所得表达式和成像规律的正确性. 关键词： 集成光学 多模干涉耦合器 相干相消 导模传输分析法

Analysis of the fully destructive interference of overlapping-images in MMI couplers

Based on self-imaging effect and overlapping-imaging properties of multimode interference couplers, the phenomenon of fully destructive interference of overlapping-images in MMI couplers is revealed, for the first time. The condition for overlapping-image fully destructive interference is derived. From the point of view of overlapping-image fully destructive interference, we explain the paired interference and the symmetric interference. The expressions of the positions and number of output images for two especial overlapping-images are also given. We prove that this kind of phenomena exists not only in the paired interference and the symmetric interference by way of an example. The influence of the positional number on the fully destructive interference images is also analyzed. And the guided-mode propagation analysis method is used to confirm the analytical results.