Waveguide-integrated graphene spatial mode filters for on-chip mode-division multiplexing.

On-chip mode-division multiplexing (MDM), as a promising method of scaling communication bandwidth, has attracted tremendous attention due to potential applications in optical interconnects ranging from intra-chip to board-to-board communications. However, the MDM technique usually suffers from signal degradation due to crosstalk between spatial modes in multimode waveguide devices. Here we design waveguide-integrated graphene spatial mode filters for on-chip MDM to overcome this limitation.