Integrated dual-mode 3 dB power coupler based on tapered directional coupler

Abstract

A dual-mode 3 dB power coupler based on silicon-on-insulator platform for mode division multiplexing system is proposed and demonstrated. The device, which consists of a tapered directional coupler and two output bend waveguides, has a 50:50 coupling ratio around the wavelength of 1550 nm for both fundamental and first order transverse magnetic (TM0 and TM1) modes. Based on asymmetrical tapered structure, a short common coupling length of ∼15.2 μm for both modes is realized by optimizing the width of the tapered waveguide. The measured insertion loss for both modes is less than 0.7 dB. The crosstalks are about -14.3 dB for TM0 mode and -18.1 dB for TM1 mode.