Mehmet Yanik, an assistant professor of electrical engineering and computer science, has invented a way to stop light pulses on a chip and release them at will. The technology could allow engineers to route and store optical data in telecommunications networks and on microchips without having to convert it to electricity.

Yanik's system traps a pulse of light in an arrangement of microscopic cavities. A fundamental challenge in designing the system was that the faster light can enter the cavities, the faster it escapes, severely limiting how long it can be stored. To overcome this problem, Yanik developed a way to adjust the cavities' refractive index, a property related to the way a material bends or reflects light. At first, light easily slips into a cavity. Once the light is inside, a small change to the index traps it. Changing the index yet again releases it. The system works quickly, making it ideal for processing data.

Four images of Yanik's light-stopping device as simulated on a supercomputer. (The wavy lines mark where parts of the device are not shown.) Light pulses enter from the left in the first row. The second row shows the light trapped in several cavities within the device. The third row shows that the light pulse stays stationary even after a long delay compared with the actual duration of the pulse. Finally, the light is released, exiting to the right.

--Kevin Bullis