Physicists Achieve Light Control in 74 Femtoseconds

An international team of physicists has created an innovative metasurface that can steer and reshape light beams in just 74 femtoseconds, without any mechanical parts, mirrors or lenses. The experimental results, published in Nature Nanotechnology, are expected to mark an important step forward for optical systems and future computing technologies. According to Ixbt.com the report states.

Developed by researchers at the University of California, Berkeley, and Tel Aviv University, the new device can deflect light by up to ±13 degrees. Control is achieved with a second light pulse that changes the material’s optical properties. The switching speed is limited only by the duration of the control pulse.

According to Nature Nanotechnology, the key to this achievement is the optical Kerr effect. Under this effect, a material’s refractive index changes under intense light. The Kerr effect is usually very weak, but it has a subfemtosecond response speed, with the electronic polarization of the material reacting almost instantaneously.

Metasurfaces and Optical Resonators

To amplify the Kerr response to a practical level, the scientists designed a resonant metasurface with a high quality factor. Its unit cells consist of silicon structures smaller than the wavelength, greatly enhancing the interaction between light and matter.

According to Claudio Hail, one of the study’s lead authors, the core idea was to create a metasurface whose optical response is not fixed during manufacturing. By changing the illumination pattern, researchers can control how the device steers and shapes light over extremely short time intervals.

Prospects for Communications Systems and Optical Computing

This technology could be highly significant for communications systems because controlling light at this speed would allow optical signals to be processed directly, without intermediate conversion to electrical current. Today, light is converted into electricity in data networks, increasing both time and energy consumption.

Steering light with a metasurface in tens of femtoseconds is being viewed as a promising approach that could make optical logic and switching a genuine alternative to electronic technologies. The authors emphasize that the work is still at a fundamental stage and that practical devices remain a long way off. Nevertheless, the discovery opens the door to fully optical computing and new architectures for quantum interfaces.