Tiny laser may speed up future computers

Silicon-based photonic crystal, full of holes to trap modes of light.

Manoharan Lab, Harvard

Ever since laptops and smartphones became a large part of our lives, power consumption has been an important factor in chip design. Gone are the days when a chipmaker gloats about the raw power of their chips; instead, efficiency and smart ways to step up and step down chip performance have come to the fore.

Separately, chipmakers are working on improvements in fundamental chip design. Every drop in gate switching voltage is a big step—halving the voltage reduces power consumption by a factor of four. A seemingly simple way to get rid of the voltage entirely would be to replace electrons with light, although that's proven impossible to date. New research performed by Japanese scientists demonstrates that light-powered interconnects may not be too far away.

Why would light be valuable? One factor in determining how much power a chip is going to consume is how far a signal has to travel. The resistance of a wire between two gates is proportional to the wire's length. Once a wire gets long enough, it would be more efficient to transcode the electronic signal into an optical one and transmit photons instead of electrons. Of course, once you're talking about communication between chips, it makes even more sense since optical signals have a much higher bandwidth. Yet despite the appeal, your computer and cell phone are bereft of optical interconnects.