Caltech Device Steers Light in 74 Femtoseconds

A team at Caltech has demonstrated a nanoscale silicon metasurface that can redirect a beam of light in just 74 femtoseconds, a time scale that is 10⁶ times faster than conventional optical switching devices. The device uses a secondary control beam to induce an ultrafast change in the metasurface’s optical properties, allowing the primary light beam to be steered almost instantaneously. The researchers measured the switching speed with time‑resolved spectroscopy and confirmed that the metasurface can maintain high efficiency and low loss during the rapid transition.

This breakthrough offers a new route to ultra‑fast photonic technologies. By enabling sub‑picosecond beam steering, the metasurface could be integrated into optical communication links, enabling higher data rates and lower latency. In addition, the compact, silicon‑based platform is compatible with existing semiconductor fabrication processes, making it a promising candidate for future photonic processors and high‑resolution sensing systems.