Earlier this month, I attended the Optical Fiber Communication Conference and Exposition (OFC), which took place in San Diego, March 5-9, 2023. Ayar Labs has had a presence at OFC for many years, attending functions, sitting on panels, and participating in presentations and workshops. However, this is the first time our company hosted a booth in which we held live demonstrations of our optical I/O solution. We also featured our technologies in our ecosystem partners’ booths, including GlobalFoundries, Quantifi Photonics, and Sivers Photonics.
I am delighted to report that the feedback we received was overwhelmingly positive. In addition to the excitement generated by our live demonstration showing 4-terabits per second (Tbps) chip-to-chip data transfer, visitors were also excited by the revealing of a prototype of our product with Intel’s detachable optical connector at the package-edge.
For those outside of the photonics/optics arena, OFC is the largest event in the world for optical communications and networking professionals. For almost 50 years, attendees have come from four corners of the globe to learn, teach, and drive the future of optical communications.
In the early days of OFC, the primary focus was on long-distance optical communications. More recently, there has been a dramatic increase in the desire for shorter-range optical communications for usage in data centers, for example. This started with rack-to-rack communication, then board-to-board, and—most recently—chip-to-chip.
One of the things we discovered at this year’s OFC was that many attendees remain unfamiliar with the diversity among the different chip-to-chip optical interconnect technologies. The following illustration, which comes from the Co-Packaged Optics 2023—Focus Data Centers report published by
Yole Intelligence, part of Yole Group, provides a good overview of the evolution and positioning of the various optical technologies.
Co-packaged optics split by technology guideline (Source: Yole Group)
As Yogi Berra famously said, “When you come to a fork in the road, take it!” The final fork in the integrated optical interconnect road is a choice between co-packaged optics (CPO) and in-package optical I/O.
The simplest way to summarize these technologies is that CPO is primarily used to implement the next generation of backward-compatible optical Ethernet technology for networking applications. Optical I/O is an in-package chiplet solution that moves data between computing, memory, and storage chips at high data rates efficiently and responsively.
Perhaps a good indicator of the strides in-package optical I/O technology has taken is that it hadn’t been formally recognized by Yole Intelligence as little as a year ago. By comparison, in its recent Co-Packaged Optics 2023—Focus Data Centers report, Yole Intelligence now forecasts that the in-package optical I/O market will grow upwards of $2.3B by 2033, significantly bigger than the projection of the co-packaged optics market.
Forecast of the in-package optical I/O market to grow from $5M in 2022 to $2.3B in 2033, with the co-package optics industry to value at $2.6B (Source: Yole Group)
Not surprisingly, all the vendors at OFC came into the arena fighting from their corner. Many were looking to stay in the game for at least one more generation by twisting the traditional architectures to deal with the barrage of technical challenges they faced. Power, latency, throughput, and flexibility demands of compute- and memory-focused applications are not a good match for Ethernet-oriented pluggable solutions no matter which way you twist them.
Some of the vendors focused on pluggable optics discovered linear drive at 200G to lower power. No one seems to know how well this will work in real deployments. Many CPO and pluggable vendors demonstrated 16-lane solutions providing 1.6-Tbps data throughput using 100 gigabits per second (Gbps) per lane at around 25W power in just the module.
As exciting as this may sound, it didn’t come close to the demonstration of Ayar Labs’ in-package optical I/O technology. Our current TeraPHY chiplet has eight optical ports, where each port has two optical fibers (one to transmit and one to receive). Each of these ports currently employs eight lambdas, where each lambda supports 32-Gbps using a simple NRZ modulation scheme. This means each optical port can simultaneously transmit and receive 256 Gbps (512 Gbps bidirectionally) efficiently and effectively. In turn, a single TeraPHY chiplet can transmit and receive 2 Tbps (4 Tbps bidirectionally).
This was the first time that anyone has shown a 4-Tbps transfer between two packaged chips using a single optical connection. As this news spread, our booth quickly became inundated with visitors. It wasn’t long before the waiting list for demonstrations was fully booked.
As word spread regarding our 4 Tbps live demo at OFC 2023,
the Ayar Labs booth quickly became inundated with visitors.
The excitement and interest mounted as we explained the outcomes of optical I/O technology for use in artificial intelligence (AI), machine learning (ML), and high-performance computing (HPC) applications in data centers. Once we’d explained the difference between co-packaged optics and optical I/O, the attendees fully grasped the results of having chiplet-based in-package optical I/O in the context of central processing units (CPUs), graphics processing units (GPUs), neural processing units (NPUs), memory controllers, and hardware accelerators of various types including field-programmable gate arrays (FPGAs).
As I previously mentioned, there was also a great deal of interest when we unveiled a prototype of our TeraPHY(™) optical I/O chiplet with the Intel detachable optical chiplet connector as shown on the right-hand side of the image below.
Different generations of optical fiber attachment technology culminated with a prototype of Ayar Labs TeraPHY(™) optical I/O chiplet with Intel Foundry Services’ detachable optical edge connector (right).
Our current solution involves optical fibers being permanently attached to the chiplet inside the package. So called “edge couplers,” the solution uses V-grooves to attach fibers to our chiplet. The ends of these fibers terminate in a connector at the end of the “pigtail.”
In addition to fiber attach methods based on V-grooves and edge couplers, we continue to look into other innovative solutions. Detachable connectors, which are smaller versions of an MPO/MTP connector, are being investigated for serviceability, reliability, and manufacturability. The pluggable nature of the connector could advance the ease of use of fiber connections.
In-package optical I/O is poised to reach the breaking point at which existing copper-based interconnects can no longer support evolving compute and data center architectures. At the Optica Executive Forum, Katharine Schmidtke from Meta discussed how AI training clusters are set to grow dramatically. She projected that if current trends in the growth of model sizes are to be sustained beyond 2025, a cluster consisting of 4,000 accelerators each equipped with >1TBps (8 Tbps) will be required. The compute network requirements are distinct from what the data network might need. This illustrates the need for optical I/O.
Schmidtke’s presentation during the Optica Executive Forum showed the compute network requirements to support AI training clusters beyond 2025 (Source: Meta)
Finally, I would like to mention the CW-WDM MSA (Continuous-Wave Wavelength Division Multiplexing Multi-Source Agreement). The mission of the organization is to standardize CW-WDM sources for emerging advanced integrated optics applications, including AI, ML, and HPC. Ayar Labs is a promoter member of the CW-WDM MSA, so I was excited by the number of companies I talked to who told me they are now interested in becoming members of the MSA.
Taking everything into account—the excitement generated by the 4-Tbps data transfer demonstration in our booth, the attention created by our technology in our ecosystem partners’ booths, the enthusiasm produced by our solution with Intel’s detachable optical chiplet connector, and the product momentum with the CW-WDM MSA—left me basking in the glow of one of the most exciting and fruitful optical conferences I’ve ever attended.
