Applied Physics

A Nanomechanical Phase Shifter

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Science  28 Feb 2014:
Vol. 343, Issue 6174, pp. 951
DOI: 10.1126/science.343.6174.951-a
CREDIT: COURTESY OF M. POOT

Information can be encoded in optical signals with a variety of parameters, usually wavelength, polarization, or phase. However, as signals propagate down optic fibers or around optical circuits, they can disperse; that is, they can acquire a phase shift that can then compromise the integrity of the encoded information. In other circumstances, one might want to control the phase of a signal to do a sort of analog computing by interfering the signal with reference signal and then monitoring the output as the subsequent changes in interference fringes. In each case, the ability to reliably control the phase is crucial. Poot and Tang describe a broadband phase shifter based on a nanoelectromechanical controlled waveguide composed of two parts. By electrically switching one side of the waveguide and varying the separation, they change the effective refractive index of the waveguide and can induce a controlled phase shift in the propagating light signal. Such a nanoelectromechanical approach should prove useful as optoelectronics shrink and move from bulk-optical to low-power on-chip components.

Appl. Phys. Lett. 104, 61101 (2014).

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