All-Optical Physical Layer NACK in AWGR-Based Optical Interconnects

Abstract

This letter, proposes and experimentally demonstrates an all-optical physical layer negative acknowledgment (AO-NACK) technique to handle contention in array waveguide grating router (AWGR)-based optical interconnects. By using back-propagation in AWGR, the packets experiencing contention are reflected back to the senders in the optical domain to serve as a physical layer negative acknowledgement to trigger the retransmission. A host-switch distance of ≈ 20 m and a packet length of 204.8 ns are used in this proof-of-principle demonstration. Notification of AO-NACKs messages and successful packet retransmission and switching is demonstrated with error-free operation at 10 and 40 Gb/s.