Three-mode multiplexer and demultiplexer utilizing trident and multimode couplers

In this paper, a simultaneous three-mode silicon (de)multiplexer using a trident coupler and a 3 × 3 multimode interference (MMI) is presented. The fundamental (TE 0 ), first-order (TE 1 ), and second-order (TE 2 ) modes at the input are successfully demultiplexed and converted to three uniform fundamental modes (TE 0 ) at the output ports. The device is designed and optimized by numerical simulation using three-dimensional beam propagation method together with effective index method. The three-mode (de)multiplexing is achieved over the whole C-band with small insertion loss ( < 0 . 9 dB) and crosstalk ( < − 17 dB). The proposed device also features with a small footprint ( 5 μ m × 400 μ m ) and a large fabrication tolerance against chip-size variations while maintaining the desired optical performance.