Applied Physics

Getting Resonators on Q

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Science  28 Sep 2012:
Vol. 337, Issue 6102, pp. 1585
DOI: 10.1126/science.337.6102.1585-c
CREDIT: C. HOHMANN, NANOSYSTEMS INITIATIVE MUNICH

Micro- or nanomechanical resonators find application in a broad range of devices, from mass and chemical sensors to mirror arrays that can dissect and direct multiple light beams to specific targets for adaptive optics and optical communication. Their mechanical response, however, tends to be fixed by their geometry. Often, the application is to a spectrum of chemical or biological species that may be sampled, requiring a range of frequencies to be measured. That then requires an array of resonators, structured rather like the strings on a harp of different geometry with varied length and thickness, and tuned to a specific frequency. Although some tunability of a single resonator has been demonstrated via electrical actuation, the frequency range of tunability is made at the expense of sensitivity of the resonator (as measured by the Q factor). Rieger et al. present a technique based on dielectric actuation and microwave readout for a single silicon-nitride string and show that the resonant frequency can be tuned over a relatively large frequency range and yet still maintain high Q factors. A single-stringed (micromechanical) instrument with the function of a multistringed harp would offer simplicity in device design.

Appl. Phys. Lett. 101, 103110 (2012).

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