Computer chips have two important parts—the logic on the chip, which computes and executes programs. Then there’s the part that sends and receives—gets data to crunch, sends back the answer. And while that first part, chip logic, has gotten much faster over the years, the transmission part has lagged behind. Because data gets sent via electrical signals passing through copper.
So researchers designed a chip that exchanges data with light instead. "By going into optics, we're able to relieve this fundamental bottleneck of copper, and in doing so we're able to increase the bandwidth density on the chip, so how fast the chip can take data in and out, by an order of magnitude." Chen Sun, a computer hardware researcher at UC Berkeley, and the startup Ayar Labs.
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A metal pin on the memory chip in your computer might transmit at 1.6 gigabits per second. Sun's optical connection ups that rate to 2.5 gigabits per second. Not a huge difference on the face of it. But the killer app here is that multiple wavelengths of light—up to 11—can be used simultaneously to send data through a single fiber. Which means this technology has potential speeds of 27.5 gigabits per second—more than an order of magnitude faster than today’s standard. "So that's the extra dimension we have to scale bandwidth that we don't have with normal electrical signals." The findings appear in the journal Nature. [Chen Sun et al, Single-chip microprocessor communicating directly using light]
These chips with optical connections are not just high-speed—they also require less energy than the copper versions. That could be a big deal, with server farms projected to outpace every other commercial use of electricity within the next decade. Going optical could thus be a win-win: faster processing using a fraction of the energy.
—Christopher Intagliata
[The above text is a transcript of this podcast.]
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