Light can carry enormous amounts of information at extreme speeds, making photonic technologies promising for the development of faster communications, more powerful computing systems and more sensitive sensors. But for light to be useful for these purposes, engineers need to be able to control where it goes and redirect it quickly. A new device built by Caltech researchers uses a beam of light to steer another to a different angle in just 74 femtoseconds (74 quadrillionths of a second). That's about the time it takes light to travel the width of a human hair.