Demand is mounting for data transmission speeds of more than 100 Gb/s to satisfy datacenters and other interconnect applications. Researchers in Europe are answering the call for energy-efficient, multi-channel optical links with fast data transfer rates.
A novel optical receiver that can achieve an aggregate bandwidth of 160 Gb/s through four optical fibers has been demonstrated by researchers from IBM Research in Zurich, Switzerland, together with a consortium working under the EU-funded project “ADDAPT." The optical receiver features link power-on/off functionality as well as the fastest data transmission speed to date. Based on complementary metal-oxide-semiconductor (COMS) technology, the system can wake-up and achieve phase-lock in eight nanoseconds, the shortest switch time on record.
The rapid power-on/off feature is expected to enhance link utilization and greatly reduce energy consumption on a chip or in an optical interconnect system. Unlike many commercial optical transceivers that are always powered on regardless of transmission activity, power would only be used when data packets are transmitted through the optical link. The design is packaged with an 850-nanometer photodiode array and targets low-cost VCSEL-based optical links for datacenter interconnects.
Link utilization in datacenters is currently less than 10 percent for 99 percent of the links. The rapid on/off functionality for the receiver was developed so that links can be powered off during idle time and powered back on when the data is ready to be transmitted, improving power efficiency in optical interconnect systems.
The optical receiver features four identical channels associated with a proposed link protocol, which is equipped with self-developed smart analog circuits to rapidly align the receiver’s clock with the arrival of incoming data, and detects the optical signal sequences to rapidly turn the link system on and off.
The receiver was tested at 40 Gb/s second with a reference transmitter consisting of an 850-nanometer Mach-Zehnder modulator followed by a variable optical attenuator. Power on/off experiments were also conducted by generating an optical signal implementing the proposed link protocol. The researchers observed correct power cycling across a 109 power cycle, and that the receiver operates error-free at 40 Gb/s second yielding 160 Gb/s aggregated bandwidth over multi-mode fibers. Data also showed that ten-percent link utilization corresponds to an 85 percent power savings on the receiver.
The next step is 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 Gb/s per channel.
The researchers will present their innovation at the Optical Fiber Conference and Exposition 2018, March 11-15 in San Diego.