HomeProjectsInformation and Communication TechnologiesMultimode Waveguide Grating Couplers for Mode Division Multiplexed High Capacity Silicon Photonics Transceivers

Multimode Waveguide Grating Couplers for Mode Division Multiplexed High Capacity Silicon Photonics Transceivers

Project Quick Facts

Principal Investigator

  • Prof. TSANG Hon Ki

    Department of Electronic Engineering

  • Funding

    Research Grants Council

  • Patent

    2 US patents filed

Mode division multiplexing in few-mode or multimode optical fibers is one of the most promising emerging technologies which can enable optical fiber interconnects to increase their data transmission capacity and bandwidth density. Current 400Gb ethernet standard optical transceivers use 4 lasers at four wavelengths, each supporting 50Gbaud PAM-4 modulation.   This is not scalable to 1.6Tb/s as it becomes too expensive to use 16 lasers in a transceiver. Besides, mode division multiplexing in multimode fibers is currently impractical because of the difficulty to selectively excite different modes with the large volume produced silicon photonic transceivers.

We have developed a new type of multimode waveguide grating coupler which will enable the use of mode division multiplexing in multimode optical fibers. A direct optical interface between multimode fiber and a silicon photonic transceiver is also developed, in which will enable mode division multiplexing in multimode fibers for high capacity short-reach data communications. The technology will enable the next generation optical ethernet to attain 800Gb/s or possibly 1.6 terabit/s capacity with a single wavelength silicon photonic transceiver interfaced with multimode fibers. We have already demonstrated this technology with few-mode fibers and are currently developing advanced designs for use with standard multimode fibers.

Schematic diagrams of simultaneous launch of 4 modes into a step-index few-mode fiber (FMF) via the novel subwavelength waveguide grating. (a) LP01−xmode, (b) LP01−ymode, (c) LP11−xmode and (d) LP11−ymode.

Uniqueness and Competitive Advantages:

  • A new technology with US patent filed
  • Avoids the need for fiber photonic lanterns which will cause additional cost and consume valuable space in the data centers
  • Allows direct multimode fiber interface to the silicon photonic transceiver without the need for any fiber break-out box
  • Simply doubles the capacity of current 400Gb ethernet to 800Gb/s with multimode fiber transmission; Further increases to 1.6Tb/s are possible with the use of additional spatial modes in the fiber
  • Applications include high capacity data center optical interconnects and 5G backhaul transceivers
Scanning electron microscope image of the fabricated multimode grating coupler with a zoom-in view shown in the inset.
Output field profiles of the step index few mode fiber when LP01−x, LP01−y, LP11−x and LP11−y are selectively launched by the multimode waveguide grating coupler.

Do you like our project?