The company earmarks 2023 for its first co-packaged optics product
Intel is sampling an 800-gigabit DR8 in an OSFP pluggable optical module, as announced at the recent OFC virtual conference and show.
Robert Blum“It is the first time we have done a pluggable module with 100-gigabit electrical serdes [serialisers/ deserialisers],” says Robert Blum, Intel’s senior director, marketing and new business. “The transition for the industry to 100-gigabit serdes is a big step.”
The 800-gigabit DR8 module has eight electrical 100-gigabit interfaces and eight single-mode 100-gigabit optical channels in each transmission direction.
The attraction of the single-module DR8 design, says Blum, is that it effectively comprises two 400-gigabit DR4 modules. “The optical interface allows you the flexibility that you can break it out into 400-gigabit DR4,” says Blum. “You can also do single 100-gigabit breakouts or you can do 800-gigabit-to-800-gigabit traffic.”
Intel expects volume production of the DR8 in early 2022. Developing a DR8 in a QSFP-DD800 form factor will depend on customer demand, says Blum.
Intel will follow the 800-gigabit DR8 module with a dual 400G FR4, expected later in 2022. The company is also developing a 400-gigabit FR4 module that is expected then.
Meanwhile, Intel is ramping its 200-gigabit FR4 and 400-gigabit DR4 modules.
51.2-terabit co-packaged optics
Intel demonstrated a prototype 12.8-terabit co-packaged optics design, where the optics is integrated alongside its Tofino 2 Ethernet switch chip, at last year’s OFC event.
The company says its first co-packaged optics design will be for 51.2-terabit switches and is scheduled in late 2023. “We see smaller-scale deployments at 51.2 terabits,” says Blum.
A comparison between pluggables and co=packaged optics. Source: Intel
Moving the industry from pluggable optical modules to co-packaged optics is a big shift, says Intel. The technology brings clear system benefits such as 30 per cent power savings and lower cost but these must be balanced against the established benefits of using pluggable modules and the need to create industry partnerships for the production of co-packaged optics.
The emergence of 800-gigabit client-side pluggable modules such as Intel’s also means a lesser urgency for co-packaged optics. “You have something that works even if it is more expensive,” says Blum.
Thirty-two 800-gigabit modules can serve a 25.6-terabit switch in a one rack unit (1RU) platform.
However, for Intel, the crossover point occurs once 102.4-terabit switch chips and 200-gigabit electrical interfaces emerge.
“We see co-packaged optics as ubiquitous; we think pluggables will no longer make sense at that point,” says Blum.
FPGA-based optical input-output
Intel published a paper at OFC 2021 highlighting its latest work a part of the U.S. DARPA PIPES programme.
The paper describes a co-packaged optics design that adds 8 terabits of optical input-output (I/0) to its Stratix 10 FPGA. The design uses Ayar Labs’ TeraPHY chiplet for the optical I/O.
The concept is to use optical I/O to connect compute nodes - in this case, FPGAs - that may be 10s or 100s of meters apart.
Intel detailed its first Stratix 10 with co-packaged optical I/O two years ago.
The latest multi-chip package also uses a Stratix 10 FPGA with Intel’s Advanced Interface Bus (AIB), a parallel electrical interface technology, as well as the Embedded Multi-die Interconnect Bridge (EMIB) technology which supports the dense I/O needed to interface the FPGA to the TeraPHY chiplet. The latest design integrates five TeraPHYs compared to the original one that used two. Each chiplet offers 1.6 terabits of capacity such that the FPGA-based co-package has 8 terabits of I/O in total.
Optically enabling Ethernet silicon or an FPGA is part of the industry’s vision to bring optics close to the silicon. Other devices include CPUs and GPUs and machine-learning devices used in computing clusters that require high-density interconnect (see diagram below).
A future XPU compute node. Source: Intel.
“It is happening first with some of the highest bandwidth Ethernet switches but it is needed with other processors as well,” says Blum.
The Intel OFC 2021 paper concludes that co-packaged optics is inevitable.
Milestones, LiDAR and sensing
Intel has shipped a total of over 5 million 100-gigabit optical modules, generating over $1 billion of revenues.
Blum also mentioned Intel’s Mobileye unit which in January announced its LiDAR-on-a-chip design for autonomous vehicles.
“We have more than 6,000 individual components on this LiDAR photonic integrated circuit,” says Blum. The count includes building blocks such as waveguides, taps, and couplers.
“We have this mature [silicon photonics] platform and we are looking at where else it can be applied,” says Blum.
LiDAR is one obvious example: the chip has dozens of coherent receivers on a chip and dozens of semiconductor optical amplifiers that boost the output power into free space. “You really need to integrate the different functionalities for it to make sense,” says Blum.
Intel is also open to partnering with companies developing biosensors for healthcare and for other sensing applications.
Certain sensors use spectroscopy and Intel can provide a multi-wavelength optical source on a chip as well as ring-resonator technology.
“We are not yet at a point where we are a foundry and people can come but we could have a collaboration where they have an idea and we make it for them,” says Blum.