Researchers stress-test an optics module at the optics lab at IBM Research’s headquarters. [Image: Ryan Lavine for IBM]
On 9 December, tech giant IBM, USA, released internal research describing a co-packaged optics (CPO) prototype that integrates polymer optical waveguides (PWG) to enable light-speed connectivity with data centers. According to the company, the technology could be used to train artificial intelligence (AI) models up to five times faster than conventional wiring and cut data center energy use by more than 80%.
A quest for speed
The announcement is the latest development in the computing industry’s quest to bring high-speed data inside data centers and onto circuit boards, as the processing demands of generative AI push the limits of Moore’s law. CPO combines optical and electronic components to enhance the efficiency of data transmission.
Although optical fiber is widely used to carry high-speed data across long distances, the racks within data centers still rely on copper-based electrical wires. These wires connect GPU accelerators that may spend most of their time idle, resulting in significant energy loss and high operating costs.
“As generative AI demands more energy and processing power, the data center must evolve—and co-packaged optics can make these data centers future-proof,” said Dario Gil, IBM senior vice president and director of research, in a press release.
CPO is an emerging solution being explored by numerous companies, several of which are clustered in Silicon Valley. Key market players include Broadcom Inc., Intel Corp., Cisco Systems Inc., and Marvell Technologies—all of which are US-based—along with Quanta Computer Inc., Taiwan, and Furukawa Electric Company Ltd., Japan.
Putting the tech to the test
The IBM researchers claim to be the first to design, assemble and announce the use of a PWG to replace traditional electrical interconnects. As they describe in a pre-print paper on research-sharing platform ArXiv, the team assembled a high-density PWG at 50-µm-pitch optical channels, adiabatically coupled to silicon photonics waveguides, using standard assembly packaging processes.
In addition, IBM notes that its CPO modules are the first to pass all the stress tests required for manufacturing. These assessments ensure that product components can function under a range of environmental conditions, including high humidity, temperatures from -40°C to 125°C and mechanical pressures causing the bending of optical fibers.
The IBM researchers claim to be the first to design, assemble and announce the use of a PWG to replace traditional electrical interconnects.
“The big deal is not only that we’ve got this big density enhancement for communications on module, but we’ve also demonstrated that this is compatible with stress tests that optical links haven’t been passing in the past,” said IBM research engineer John Knickerbocker in a blog post accompanying the announcement. To optimize production costs, IBM’s modules are meant to be compatible with standard electronic passive advanced packaging assembly processes.
Far-reaching potential
According to IBM’s paper, the company’s new module could: save the energy equivalent of 5,000 US homes’ annual power consumption per AI model trained; reduce the time it takes to train a large trillion-parameter model from three months to three weeks; enable chipmakers to add six times as many optical fibers at the edge of a silicon photonics chip and extend the length of data center interconnect cables from one to hundreds of meters.
IBM’s CPO model may compete with other technologies under development to address the low power consumption and high bandwidth demands of data centers, such as linear pluggable optics.
While IBM did not share information about product timeline or availability, the company indicated that it is pursuing a roadmap. In addition, the team is testing prototypes with sub-20-µm-pitch waveguides, increased waveguide channels and multiple wavelength (lambda) compatible hardware demonstrations. Findings are expected in 2025.