Researchers at the University of Michigan have developed a semiconductor device that uses laser light to direct the movement of electrons without requiring an applied electric field or electrical power source — an "electron lighthouse."
The device, built at the Lurie Nanofabrication Facility, was primarily designed to investigate fundamental physics. However, the discovery could eventually support technologies combining optics and electronics, including advanced sensing, imaging, and telecommunications.
"This electrical device has the potential to turn into something that measures different aspects of light," said Yiming Gong, who led the project as a doctoral student. "But this originates from a very fundamental level of physics, which is the interference between different optical absorption processes."
Two colors of light produce an organized flow of electrons through a semiconductor. The direction of the current changes by rotating the polarization of the optical fields.
"This isn't the way things normally work. When you think about electrons moving through a material, they're moving because you've applied an electrical field," said Steven Cundiff, senior author. "Here, using light, you can actually sort of squirt the electrons in a specific direction without applying an electric field."
Cundiff compares the effect to a lighthouse sweeping a beam across the horizon. The effect, first predicted by **J.E. Sipe** of the University of Toronto, depends on quantum interference between two optical absorption pathways.
The research was published in Physical Review Letters and supported by the U.S. National Science Foundation.
