Novel 1-to-N way integrated optical beam splitters using symmetric mode mixing in GaAs/AlGaAs multimode waveguides

Abstract
We report the demonstration of novel GaAs/AlGaAs integrated optical 1‐to‐N way beam splitters which use symmetric mode mixing in center‐fed multimode planar waveguides. Each device has one single‐mode input guide, a carefully chosen length of parallel sided multimode guide, and N equally spaced single‐mode output guides. The mixing of symmetric modes shares the input light equally between the output guides by a symmetric form of the self‐imaging process. We demonstrate experimentally that this type of beam splitter can be used to divide power equally, with high accuracy and low loss, between the N output guides, for values of N between 2 and 20.