Fig 1: A microscale mechanical switch on a silicon chip.

At the tiny sizes of integrated photonics, an optical signal can generate enough mechanical force to physically move a small object, such as the tip of a cantilever. Researchers at the University of Minnesota used this property to create an optomechanical force to deflect the cantilever. Because the cantilever contained an optical waveguide, they were able to modulate the optical signal passing through the cantilever using only optically passive materials (Nat. Comm. 3:1091, 2 Oct 2012).

Fig 1: A microscale mechanical switch on a silicon chip uses light from a microring to deflect a cantilevered light guide (foreground), thus modulating the signal.

The force is supplied by an optical control coupled into a microring resonator. The cantilever acts like a spring, thus creating an intensity sine wave in the output signal. Because the power of the second optical signal can be many times higher than the control signal, the device functions like a mechanical relay to amplify the input signal. "This is the first time that this novel optomechanical effect is used to amplify optical signals without converting them into electrical ones," group leader Mo Li said.

To read more: http://www.osa-opn.org