University researchers develop light-powered microchips

BOULDER — Researchers at the University of Colorado Boulder are part of a team that has developed a microprocessor chip that uses light, which could pave the way for faster computing systems and network infrastructure while using less energy, CU announced Wednesday.

Researchers at CU, the University of California Berkeley and the Massachusetts Institute of Technology developed the light-based circuits that can transfer data at rapid speeds while using minute amounts of energy.

“Light-based integrated circuits could lead to radical changes in computing and network chip architecture in applications ranging from smartphones to supercomputers to large data centers, something computer architects have already begun work on in anticipation of the arrival of this technology,” said Miloš Popović, an assistant professor in CU-Boulder’s Department of Electrical, Computer, and Energy Engineering and a co-corresponding author of the study.

Traditional microprocessor chips —found in everything from laptops to supercomputers — use electrical circuits to communicate with one another and transfer information. In recent years, however, the sheer amount of electricity needed to power the ever-increasing speed and volume of these data transfers has proved to be a limiting factor.

To overcome this obstacle, the researchers turned to photonics, or light-based, technology.  Sending information using light rather than electricity reduces a microchip’s energy burden because light can be sent across longer distances using the same amount of power.

“One advantage of light-based communication is that multiple parallel data streams encoded on different colors of light can be sent over one and the same medium — in this case, an optical wire waveguide on a chip, or an off-chip optical fiber of the same kind that as those that form the Internet backbone,” said Popović, whose CU-Boulder-based team developed the photonic device technology in collaboration with a team led by Rajeev Ram, a professor of electrical engineering at MIT.

“We figured out how to reuse the same materials and processing steps that comprise the electrical circuits to build high-performance optical devices in the same chip,” said Mark Wade, a Ph.D. candidate at CU-Boulder and a co-lead author of the study. “This allows us to design complex electronic-photonic systems that can solve the communication bottleneck in computing.”

The research has resulted in two startups, including Ayar Labs, which specializes in energy-efficient, high-volume data transfers. Under its former name of OptiBit, Ayar Labs won the Department of Energy-sponsored MIT Clean Energy Prize earlier this year.

The study was co-authored by Jeffrey Shainline, Rajesh Kumar and Fabio Pavanello, all of CU-Boulder; Chen Sun, Yunsup Lee, Andrew Waterman, Rimas Avizienis, Sen Lin, Henry Cook, Albert Ou, and Krste Asanović, all of the University of California Berkeley; and Jason Orcutt, Luca Alloatti, Michael Georgas, Benjamin Moss, Amir Atabaki, Jonathan Leu, Yu-Hsin Chen and Rajeev J. Ram, all of Massachusetts Institute of Technology.

The Defense Advanced Research Projects Agency provided support for this research.

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