Silicon-based multimode waveguide crossings

Abstract

Mode multiplexing technique is a new promising option to increase the transmission capacity of on-chip optical interconnects. Multimode waveguide crossings are the key building blocks in high-density and large-scale mode division multiplexing silicon photonic integrated circuits. In this paper, we review the recent progresses on silicon-based multimode waveguide crossings. Firstly, a variety of multimode waveguide crossing schemes are demonstrated and introduced including conventional multimode interference coupler, Maxwell's fisheye lens and inverse-designed multimode interference coupler. Secondly, we also discuss some emerging applications of the inverse design algorithm in the multimode silicon devices to realize ultracompact footprint and multiple functionalities. Finally, we also give the outlook of the development prospects of on-chip multimode waveguide crossings.

Expanding the Quantum Photonic Toolbox in AlGaAsOI

“…Several methods have been explored for creating lowloss waveguide crossings including vertical coupling into polymer strip waveguides 38 , multi-planar crossings 39 , multimode interference-based crossings [40][41][42] , and subwavelength gratings 43 . Many of these methods involve additional fabrication steps that can introduce excess loss and system design and fabrication challenges.…”