A paradox that has long vexed researchers in the field of optics is that, to control a light source, another light source that uses as much energy—if not more—is typically required. The setup works, but it is not efficient.

A new study from the School of Engineering and Applied Sciences at the State University oA weak control beam (narrow red line, far right) and a more intense laser signal (larger red line, far left) within an asymmetrical metawaveguide (purple box). Image credit: SUNY Buffalo.f New York at Buffalo (SUNY Buffalo), the California Institute of Technology and the City University of New York reports that researchers have now demonstrated a way to control light with light using only one-third of the energy typically required—and in some cases less. The study's authors have developed a metawaveguide—a tiny rectangular box made of silicon, the semiconducting material for computer chips—that creates asymmetric reflections of the two beams of light, allowing the weaker beam to control the other beam. "Typically, symmetry connotes harmony and beauty. But not in this case," says Liang Feng, assistant professor in the Department of Electrical Engineering at SUNY Buffalo. "We've developed technology—an asymmetric metawaveguide—that enables a weak control laser beam to manipulate a much more intense laser signal."

According to the researchers, the advancement, coupled with other developments, could ultimately lead to more powerful, energy-efficient computer chips and new optics-based technologies.