Photonic Forces Cause Mechanical Vibration

The force of light can be used to drive a nanoscale mechanical oscillator, according to a new study. Intense beams of photons have been used before as "optical tweezers," where single particles are captured in the optical gradient forces formed by laser beams. Now, Hong X. Tang, a professor in the electrical and mechanical engineering departments at Yale University, and colleagues have been able to build an integrated nano-optical circuit and use the circuit's optical gradient force to vibrate a bridge of silicon about 10 ??m long and 500 nm wide, in the nano-optical circuit (Nature 2008, 456, 480). The bridge acts both as the "waveguide" through which the light is sent and as the oscillating object itself. The discovery has wide-reaching implications for the field of nanophotonics, says Tobias J. Kippenberg, of the Swiss Federal Institute of Technology, in Lausanne, in an accompanying commentary, and "points to a whole new class" of devices such as optically driven mechanical oscillators with photonic functionality and narrow-band radio-frequency filters.