Researchers at the California Institute of Technology have achieved a milestone in photonics by developing a surface capable of steering and reshaping light in just 74 femtoseconds. A femtosecond is one quadrillionth of a second. This speed represents a significant departure from current hardware that relies on mechanical movement or electrical signals to adjust light beams.
The device is a metasurface made of tiny silicon structures. These structures are smaller than the wavelength of light. By concentrating light into these structures, the researchers amplify the optical Kerr effect. This phenomenon allows one pulse of light to change the refractive index of the silicon, which in turn alters the path of another light beam passing through the surface.
This technology provides a path toward all-optical systems. Current communication networks frequently convert light into electrical signals for processing and then back into light for transmission. This conversion creates delays and increases energy consumption. A reconfigurable metasurface could allow these operations to remain in the optical domain from start to finish.
The team demonstrated the capability to redirect a light beam by up to 13 degrees. They also successfully reshaped the output by simply changing the spatial pattern of the control pulse. Because the process does not depend on moving parts, it resets near-instantaneously as soon as the control pulse finishes. This allows for high-speed, programmable control of light properties.
While this remains a proof of concept, the study confirms that nanoscale engineering can overcome the inherent weakness of light-matter interactions. Future applications for this technology include faster communication hardware, advanced imaging sensors, and photonic computing. The findings were published in Nature Nanotechnology.