Data centre routing ASIC with integrated optics

The switching ASIC employs unique low-power custom circuitry to interface to Rockley-developed photonic chips. Advanced technology for fibre-optic assembly delivers significantly lower power than conventional ASICs that use electrical IO and external optical transceiver modules.

By driving optical fibre directly from the package, the Rockley product can directly connect to devices placed 500 meters away, offering a 100x improvement over today’s ASICs using all-electrical IO.

The Rockley Photonics platform employs innovative technologies while leveraging established assembly processes to deliver a novel solution that is both highly advanced, while suitable for high-scale manufacturing. The product employs an L3 routing ASIC designed by Rockley Photonics and silicon photonics chips manufactured on a Rockley proprietary process.

The switch ASIC and silicon photonics ICs are placed into a customised package enabling fibre-optic links to connect directly into the assembly. Innovative mixed-signal circuit designs enable the photonics ICs to be driven directly by the ASIC without additional chips.

The Rockley solution was developed in cooperation with major industry partners to be suitable for rapid transition to manufacturing scale. The ASIC was manufactured in TSMC 28nm process technology. The package substrate manufacture, chip assembly and test was performed by IBM.

The silicon photonics ICs were manufactured by established third-party fabrication houses using Rockley Photonics’ advanced process. The final assembly was performed by Fabrinet.

“The Rockley Photonics OpticsDirect System represents a culmination of multiple years of development effort by the entire Rockley team as well as our ecosystem partners,” said Dr. Andrew Rickman, founder and CEO of Rockley Photonics. “We are pleased and excited to deliver this important new platform which will usher in the modern era of integrated optics.”

The Rockley Photonics demonstration involves multiple ports of 100G directly connected using single mode fibre with 25G optical modulation. The integrated Rockley single-chip switch provides Ethernet MAC capability, plus packet processing, packet buffering, and L3 routing between ports.

The Rockley switch reference platform exhibits very low power consumption, with significant power savings enabled by the direct fibre-optic interconnect. This approach significantly reduces data center CapEX, OpEX and TCO.

“By eliminating all electrical interconnect and driving the optics directly from the ASIC, Rockley has achieved unprecedented low power levels,” said Amit Nagra, Chief Operating Officer at Rockley Photonics. “In fact, we estimate the switch, with optics, consumes less power per 100G port than a typical optical transceiver.”

Although the demonstration leverages a Rockley-designed ASIC, the OpticsDirect platform can enable any customer ASIC platform to become ‘optics enabled’. Rockley Photonics plans to partner with third-party developers of digital ASICs to develop all-optical product designs, combining Rockley Photonics technology with world-leading digital ASIC architectures.

“As modern communication systems demand higher speed interconnect, the industry will increasingly look to optics to drive new product innovations.” said Nick Kucharewski, Chief Commercial Officer at Rockley Photonics.

“The Rockley OpticsDirect system enables any developer of digital ASICs to migrate their designs to directly-connected optics, to eliminate the bottlenecks on power consumption and physical reach common with electrical interconnects.”

The Rockley platform is well suited to any application requiring highly efficient high-speed interfaces from 25G per lane and beyond. This includes data center switching, server controller and storage endpoints, cluster computing and HPC, and deep-learning applications.

Outside the data center, the technology is well suited to applications requiring connectivity beyond the reach of copper cables, such as passive optical networking (PON), mobile-fronthaul networks, and advanced 5G mobile compute infrastructure.