You can't feel it, but light can exert forces. And it has now been used to drive a tiny mechanical resonator, opening the door to a new way of powering nanoscale machinery. The device was developed by Hong Tang's team at Yale University. It contains a waveguide - a kind of constricting channel for light-which sends light through a bottleneck in a silicon photonic circuit. That 1011m long, 110nm wide channel constrains the light, causing the material to resonate at right angles to the beam.
This vibration is the result of the so-called optical gradient force, which kicks out sideways from the light beam. Because light can be easily beamed onto large areas, many such photonic circuits could be driven at once. The Yale team's work is the first to demonstrate that those forces can be usefully collected in even smaller, nanoscale circuits. They say their photonic circuits could be used to control other small-scale devices, such as electronics or light-based computer chips.