spotlight

A new angle on controlling light

This video shows the full process of the experimental setup, with the sample rotating 90 degrees.

Light waves can be defined by three fundamental characteristics: their color (or wavelength), polarization, and direction. While it has long been possible to selectively filter light according to its color or polarization, selectivity based on direction has remained elusive.

But now, for the first time, MIT researchers have produced a system that allows light of any color to pass through only if it is coming from one specific angle; the technique reflects all light coming from other directions. This new approach could ultimately lead to advances in solar photovoltaics, detectors for telescopes and microscopes, and privacy filters for display screens.

The work is described in a paper appearing this week in the journal Science, written by MIT graduate student Yichen Shen, professor of physics Marin Soljačić, and four others. "We are excited about this," Soljačić says, "because it is a very fundamental building block in our ability to control light."

Video credit: Yichen Shen. Courtesy of Science.