Simultaneous Mode and Wavelength Division Multiplexing On-Chip

Significant effort in optical-fiber research has been put in recent years into realizing mode-division multiplexing (MDM) in conjunction with wavelength-division multiplexing (WDM) to enable further scaling of the communication bandwidth per fiber. In contrast almost all integrated photonics operate exclusively in the single-mode regime. MDM is rarely considered for integrated photonics due to the difficulty in coupling selectively to high-order modes which usually results in high inter-modal crosstalk. Here we show the first demonstration of simultaneous on-chip mode and wavelength division multiplexing with low modal crosstalk and loss. Our approach can potentially increase the aggregate data rate by many times for on-chip ultra-high bandwidth communications. Current integrated photonics operate almost exclusively in the single-mode regime and utilize wavelength-division multiplexing (WDM) which supports a limited scalability in bandwidth density. In contrast fiber communications is increasingly targeting multimode operation in conjunction with WDM to further scale the communication bandwidth transmitted