Harvard engineers build chip that can twist and control light in real time

Scientists at Harvard have built a miniature device that can twist and tune light in real time. By rotating two stacked photonic crystals and adjusting their spacing with a tiny mechanical system, they can control how light’s “handedness” behaves. This allows the chip to distinguish between left- and right-circular polarized light with remarkable precision. The advance could lead to smarter sensors, faster communications, and new quantum technologies.