IBM to present ADDAPT four-fiber 160-Gbps receiver with record on/off times at OFC 2018

Representatives from IBM Research and fellow members of the EU-funded Adaptive Data and Power Aware Transceivers for Optical Communications (ADDAPT) program will deliver a paper on their work to design an optical receiver that can support an aggregate bandwidth of 160 Gbps via four optical fibers. The CMOS-based receiver features a link power-on/off functionality that can activate and achieve phase-lock in 8 ns, which the researchers assert is the shortest switch time on record.

Representatives from IBM Research and fellow members of the EU-funded Adaptive Data and Power Aware Transceivers for Optical Communications (ADDAPT) program will deliver a paper on their work to design an optical receiver that can support an aggregate bandwidth of 160 Gbps via four optical fibers. The CMOS-based receiver features a link power-on/off functionality that can activate and achieve phase-lock in 8 ns, which the researchers assert is the shortest switch time on record.

"Our design, for the first time, allows for the on/off switching of and optical link on a per-packet basis," according to Alessandro Cevrero, the primary author of the paper and a scientist of IBM Research Lab, Switzerland. "There were previous scientific attempts to turn off the links when there is no data; however, the timescale to switch on and off the link was orders of magnitude longer than that of an individual data packet. To achieve shorter power-on time at a very high data transmission speed is the key challenge."

The researchers say the rapid power-on/off feature will reduce energy consumption on a chip or in an optical interconnect system, as the receiver would only use power when data packets are transmitted through the optical link. The receiver consumes about 88 mW in its power-on state, says Cevrero.

The optical receiver leverages four identical channels associated with a proposed link protocol. The link protocol is equipped with smart analog circuits that can rapidly align the receiver's clock with the arrival of the incoming data and detects the optical signal sequences to rapidly turn the link system on and off.

The researchers say they tested the receiver at 40-Gbps second with a reference transmitter consisting of an 850-nm Mach-Zehnder modulator followed by a variable optical attenuator. They also performed power on/off experiments by generating an optical signal that implemented the proposed link protocol. The receiver demonstrated correct power cycling across a 109 power cycle and performed error free, thus supporting 40-Gbps per channel and 160 Gbps in aggregate over multimode fibers. The experimental data showed that 10% link utilization corresponds to 85% power saving on the receiver.

Cevrero said the researchers plan to validate a complete optical interconnect system by measuring the optical transmitter, as well as to increase the data transmission speed on the receiver side to 56 Gbps per channel.

The paper describing this research, "4x40 Gb/s 2 pJ/bit Optical RX with 8ns Power-on and CDR Lock Time in 14nm CMOS," by A. Cevrero, I. Ozkaya,T. Morf, T.Toifl, M. Seifried, F. Ellinger, M.Khafaji, J. Pliva, R. Henker, N. Ledentsov, J.-R. Kropp, V. Shchukin, M. Zoldak, L. Halmo, I. Eddie, and J. Turkiewicz, will be presented Monday, March 12, 2018 as part of the "Energy Efficient Optical Links" session (M2D).

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