University of Utah engineers have taken a big step toward computing at the speed of light. Their research will help create the next generation of computers and mobile devices-devices that will be capable of speeds millions of times faster than machines are now.
The Utah team have developed an ultracompact beamsplitter-the smallest on record. The beamsplitter divides light waves into two separate channels of information. Its purpose is to make the production of silicon photonic chips possible.
These chips are what will be the key to moving information with light rather than electrons. Computing at its core is information moving and processing. The team headed by Rajesh Menon, the principal author of the study and an associate professor of electrical and computer engineering, describes the breakthrough invention today in the journal Nature Photonics.
Silicon photonics will also significantly increase the speed and power of machines such as data center servers, supercomputers, and the specialized computers that autonomous cars and drones use for collision detection. Eventually, the technology could reach home computers and mobile devices and improve applications from gaming to video streaming.
"Light is the fastest thing you can use to transmit information," says Menon. "But that information has to be converted to electrons when it comes into your laptop. In that conversion, you're slowing things down. The vision is to do everything in light."
Photons of light carry information over the Internet through fiber-optic networks. However, the electron conversion process slows everything down once the data stream reaches a home or office machine. That's because the photons of light must be converted to electrons before they can be handled by a router or computer. But if the data stream could remain light inside computer processors, that bottleneck would disappear.
"With all light, computing can eventually be millions of times faster."
Light is easy to contain and travels as quickly as possible while losing less information, making it the goal form of information transmission. The Utah team created a much smaller form of a polarization beamsplitter on top of a silicon chip. It looks much like a barcode, but its purpose is to split incoming light into its two components: electrical and magnetic energy.
In the past, this kind of beamsplitter was over 100 by 100 microns, but this design, created by the team's new algorithm, has shrunk it to 2.4 by 2.4 microns. This means it is one-fiftieth the width of a human hair and close to the limit of what is physically possible.
The beamsplitter would play just one of a multitude of roles in the overall goal of light direction. The various passive devices would be placed on a silicon chip to direct light waves in different ways. By shrinking the devices down in size, researchers will be able to cram millions of these devices on a single chip.
Potential advantages go beyond processing speed. The Utah team's design would be cheap to produce because it uses existing fabrication techniques for creating silicon chips. And maybe even more exciting to consumers, this photonic chip technology would allow for longer battery life and less heat generation in mobile devices. This is because by shuttling photons instead of electrons, mobile devices with this technology would consume less power.
The first supercomputers using silicon photonics are already under development at companies like Intel and IBM. These machines will use hybrid processors that remain partly electronic. Menon believes his beamsplitter could be used in those computers in about three years. He adds that data centers that require faster connections between computers should also be able to implement the technology soon.
