Equalizer State Caching for Fast Data Recovery in Optically-Switched Data Center Networks

Optical switching offers the potential to significantly scale capacity of data center networks (DCN) with a simultaneous reduction in time and power consumption. Previous research has shown that end-to-end time, which is sum switch configuration clock recovery (CDR) locking should be kept within few nanoseconds for high network throughput. This challenge low motivated into fast optical switches, ultra-fast amplitude techniques. Concurrently, rate between server-to-server server-to-switch interconnect increasing drastically from current 100 Gb/s (4 × 25 Gb/s) 400 beyond, motivating use order formats such as 50-GBaud four-level pulse-amplitude modulation (PAM-4) signalling. Since PAM-4 more sensitive noise distortion, digital equalizers are generally needed compensate impairments transceiver frequency roll-off, dispersion filtering, adding additional equalizer adaptation consumption undesired systems. Here we propose investigate an state caching technique reduces computation systems, underpinning optically-switched DCNs using baud impairment-sensitive formats. Through proof-of-concept experiment, study performance proposed scheme three-node system 56 GBaud PAM-4. Our experimental results show can tolerate up ±0.8-nm (±100-GHz) instantaneous wavelength change delay only 0.36 ns. Practical considerations phase misalignment, temperature-induced drift, precision also studied.