TECHNOLOGY FOR CHANGE

Yale Scientists Give Light Push to Nanodevices

Stan Gibson | Date: 07-23-09 | Comments

Light-based computing is attractive because photonic processors would produce no heat but run faster than conventional microprocessors.

The use of light waves on microprocessors got a push in the right direction when Yale University scientists demonstrated that light on a chip can exert a repulsive or pushing force. The new force complements a previously demonstrated pulling force.

The two forces are thought to be essential for light-based processing to work, because they could turn switches on and off on a silicon chip.

Light-based computing is attractive because photonic processors would produce no heat but run faster than conventional microprocessors, according to Hong Tang, assistant professor at Yale's School of Engineering & Applied Science, who led a team of researchers on the project. The need to cool conventional microprocessors has become an obstacle to creating more powerful devices.

Tang said the development could prove particularly beneficial in networking devices such as routers and switches that are connected to optical fiber lines. Currently, impulses must be converted from electrical to optical and vice versa as they move across devices and networks. That conversion, which wastes time and energy, would not be necessary if electrical devices were replaced with optical ones, Tang explained.

�We want to use this effect to make better routing devices,� Tang said.

To create the pushing force, the researchers split a beam of infrared light in two, forcing each smaller beam to travel a different length down a silicon waveguide, a tiny tube on a silicon chip. Doing so caused each beam to fall out of phase with the other, which created a repulsive force. The force increased the further out of phase the beams became. While the demonstration is not an actual computing device, engineers could develop such a device using the principle demonstrated by his team, said Tang.

Funding for the project includes a seed grant from the U.S. Defense Advanced Research Projects Agency and a Young Faculty Award from the National Science Foundation.