Nano Lett. 16, 2680–2685 (2016)

Optical nanoantennas have potential applications in optomechanics, sensing and active plasmonics. However, a limitation is that their resonance frequency of operation is usually fixed by their size, shape and composition. Now, Kai Chen and co-workers in Germany have demonstrated reconfigurable nanoantennas operating in the visible spectral range. Plasmonic nanoantennas were made from a pair of closely spaced, parallel single-crystal gold wires by focused-ion beam milling. The antennas were suspended 300 nm above the bottom of a trench in a glass substrate. As a voltage was applied, equal charges were induced on both antenna wires. The resulting equilibrium between the repulsive Coulomb force and the restoring elastic bending force changed the gap between the antenna wires from 40 nm at 0 V to 70 nm at 20 V, tuning the antenna's spectral response. White-light scattering spectra of the nanoantenna without an applied voltage showed a resonance peak at 730 nm that shifted to a shorter wavelength of 713 nm at 40 V.