Experimental Demonstration of a Photonic Frame Based Packet Switched Optical Network for Data Centers

This article reports on the design and the experimental realization of packet-switched optical network (PSON) for a data center network. In PSON, an optical interconnect consists of a combination of a fast tunable laser (FTL), an arrayed waveguide grating router, and a burst mode receiver (BMR). The conventional FTL transmitters can only accommodate short fixed-size photonic frame (PF) of tens of microseconds rather than variable-size PF due to the short-term wavelength stability. By using the FTL with a thermal compensation method, the PSON can support variable-size PFs with extended size to minimize the switching overhead in the optical switch domain. Our PSON system can achieve up to 96% throughput of 10 GbE service as the end-to-end optical switching time is reduced to 1.94  $\mu$ s that requires only 3  $\mu$ s guard-time in a 45  $\mu$ s time-slot. Total switching time includes wavelength conversion time of FTL, response time of BMR and burst mode-clock and data recovery (BM-CDR). Our PSON will achieve near non-blocking scheduling by use of a centralized scheduler running a grant-aware (GA) scheduling algorithm, which can be further improved to be non-blocking scheduling with a novel algorithm called C-RRP. The C-RRP scheduling algorithm is designed especially for the non-uniform distribution. Simulation results show that C-RRP improves the throughput and latency performance in hot-spot conditions.