Researchers at the California Institute of Technology and the University of California, San Diego have discovered a way to prevent light signals on a silicon chip from reflecting backwards and interfering with its operation.

Otherwise, the light beams would interfere with lasers and other photonic components on the chip and make the chip unstable. The breakthrough marks a significant achievement in the development of integrated photonic chips that could replace electronic chips as the backbone of information technology.

Lab versions of photonic chips are already supporting data transfer rates of 10 gigabits per second, and in just five years, photonic chips could achieve data transfer rates of over 40 Gbps — an order of magnitude higher than the speed of today’s networks. The shift towards optical networks will make information sharing faster, more energy-efficient and less costly.

Electronic chips rely on a diode to isolate electrical signals, enabling current to travel in just one direction and prevent interference. To achieve the same functionality, the research team developed a metallic-silicon optical waveguide system to channel light so it travels in different patterns depending on its propagation direction.

The pattern is symmetric when traveling forward and asymmetric when reflected backwards along the same path. Similar to the diode in electronics, the backscattered light is dissipated as a result.

“This discovery will help to realize a long-term goal of combining electronics with photonics to enable scalable, energy-efficient and cost-effective technology that will have a tremendous impact on such information systems as supercomputers, the Internet, and data centers,” said Yeshaiahu (Shaya) Fainman, professor and chair of the UC San Diego Department of Electrical and Computer Engineering.

“Computer technology will be able to handle a lot more data, faster and at lower cost, which will benefit large-scale business and government users as well as gadget-loving consumers.”

Ref.: Liang Feng et al., Science 5 August 2011: Vol. 333  no. 6043  pp. 729-733 DOI: 10.1126/science.1206038