Integrated Dual-Mode 3-dB Power Splitter Based on Multimode Interference Coupler

Abstract

We design and experimentally demonstrate a dualmode 3 dB power splitter based on the self-imaging effect in a taper-assisted multimode interference (MMI) coupler. The quality reduction of the two mirrored half-power images of the input field due to accumulated high-order eigenmodes phase error will degrade the performance of dual-mode power splitter. We propose an eigenmode-selective-excitation method to suppress the excitation of high-order eigenmodes in the MMI. By optimizing the geometric parameters and injection position of the input taper waveguide, we realize power ratios of 95.9 % and 94.2 % for the lowest three and five eigenmodes when input TE <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0</sub> and TE <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">1</sub> modes, respectively. The fabricated device occupies a footprint of 5 μm × 86.5 μm with 5.2 μm assisted tapers. The measured excess losses and crosstalks for both modes are less than 0.76 dB and -20.5 dB, on average, over the observable 60 nm bandwidth, respectively, which are consistent with the numerical simulations.