On-chip three-mode (de-)multiplexer based on a grooved waveguide MMI coupler on an InP platform

A compact on-chip three-mode (de-)multiplexer based on a grooved waveguide multimode interferometer (GW-MMI) coupler was demonstrated on an indium phosphide (InP) platform for the first time. Two grooves were incorporated into the GW-MMI structure to facilitate the generation of three discrete waveguides that would effectively confine the selfimages and enhance the phase-matching condition between them, resulting in a significantly more compact MMI length of just 198 mu m. The ridge waveguides were fabricated using a conventional contact lithography process, which is both straightforward and cost-effective. The measured insertion losses of the TE0, TE1, and TE2 modes are 2.9 dB, 7.53 dB, and 4.05 dB, respectively. Furthermore, the 3 dB bandwidths for all modes are larger than 13.5 nm in comparison to the value at 1550 nm. (c) 2025 Optica Publishing Group under the terms of the Optica Open Access Publishing Agreement