Nanoscale chip redirects light in quadrillionths of a second
Caltech researchers have built a device that uses one light beam to redirect another in just 74 femtoseconds. The chip relies on a nanoscale silicon metasurface to enhance light-matter interaction. This advance could lead to faster photonic communication and computing systems.
The device's speed advantage stems from its use of the optical Kerr effect, where an intense pump beam briefly alters a material's refractive index by shifting electron motion within orbitals rather than exciting electrons into longer-lived states. This avoids the relaxation bottleneck that limits conventional modulators—such as liquid-crystal panels and telecom optical chips—to nanosecond or picosecond switching times. To overcome the Kerr effect's inherent weakness, the team engineered an ultrathin silicon metasurface with nanoscale pillars that amplifies light-matter interaction, enabling the probe beam's deflection to follow the pump's projected pattern almost instantaneously.
The research, led by Claudio Hail during his Caltech postdoctoral tenure under Harry Atwater, was published in Nature Nanotechnology. Atwater notes that metasurfaces are key to boosting interaction strength for efficient light-steering. Hail has since moved to UC Berkeley as an assistant professor of mechanical engineering.
This advance could accelerate photonic communication and computing by removing a fundamental speed barrier in light modulation. Data centers, telecommunications networks, and optical sensors may eventually benefit from switching speeds thousands of times faster than current technologies, potentially enabling higher-bandwidth transmission and more responsive optical systems. However, practical deployment remains uncertain, as laboratory demonstrations must be translated into manufacturable, scalable devices. Researchers and industry engineers are the most immediate audience, while broader societal effects—such as faster internet infrastructure or advanced sensing—would likely emerge only after years of further development and commercialization.