Photon force harnessed to do some light work

2019-03-14 12:19:01

By Colin Barras You can’t feel it, but light can exert forces. And one has now been used to drive a tiny mechanical resonator, in a proof of principle that opens the door to a new way of powering nanoscale machinery. The new device (pictured right) 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 (see image). That 10-micrometer-long, 110-nanometer-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. Resonators can be powered in other ways, for example using electricity. But at nanoscales the intensity of light is great enough to exert a physical effect on the material. Because light can be easily beamed onto large areas, many such photonic circuits could be driven at once. The gradient force is a key component in “optical tweezers“, used to control microscopic objects using laser beams. 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. Journal reference: Nature: (DOI: 10.1038/nature07545) More on these topics: