New laser makes silicon 'sing'

Yale scientists have created a new type of silicon laser that uses sounds waves to amplify light. A study about the discovery appears June 8 in the online edition of the journal Science.

In recent years, there has been increasing interest in translating optical technologies—such as fiber optics and free-space lasers—into tiny optical or "photonic" integrated circuits. Using light rather than electricity for integrated circuits permits sending and processing information at speeds that would be impossible with conventional electronics. Researchers say silicon photonics—optical circuits based on silicon chips—are one of the leading platforms for such technologies, thanks to their compatibility with existing microelectronics.

"We've seen an explosion of growth in silicon photonic technologies the past few of years," said Peter Rakich, an associate professor of applied physics at Yale who led the research. "Not only are we beginning to see these technologies enter commercial products that help our data centers run flawlessly, we also are discovering new photonic devices and technologies that could be transformative for everything from biosensing to quantum information on a chip. It's really an exciting time for the field."

The researchers said this rapid growth has created a pressing need for new silicon lasers to power the new circuits—a problem that has been historically difficult due to silicon's indirect bandgap. "Silicon's intrinsic properties, although very useful for many chip-scale optical technologies, make it extremely difficult to generate laser light using electrical current," said Nils Otterstrom, a graduate student in the Rakich lab and the study's first author. "It's a problem that's stymied scientists for more than a decade. To circumvent this issue, we need to find other methods to amplify light on a chip. In our case, we use a combination of light and sound waves."