Light modulation

Much of our electronics could soon be replaced by photonics, in which beams of light flitting through microscopic channels on a silicon chip replace electrons in wires. Photonic chips would carry more data, use less power and work smoothly with fibre-optic communications systems. The trick is to get electronics and photonics to talk to each other.

Now Cornell University researchers have taken a major step forward in bridging this communication gap by developing a silicon device that allows an electrical signal to modulate a beam of light on a micrometer scale.

Other electro-optical modulators have been built on silicon, but their size is on the order of millimetres, too large for practical use in integrated circuit chips. Smaller modulators have been made using compound semiconductors such as gallium arsenide, but silicon is preferable for its ability to be integrated with current microelectronics.

The work is described in a paper published in the May 19, 2005, issue of Nature by Michal Lipson, Cornell assistant professor of electrical and computer engineering, and her research group.