We demonstrate plasmon-mechanical coupling in a metalized nanomechanical oscillator. A coupled surface plasmon is excited in the 25 nm wide gap between two metalized silicon nitride beams. The strong plasmonic dispersion allows the nanomechanical beams’ thermal motion at a frequency of 4.4 MHz to be efficiently transduced to the optical transmission, with a measured displacement spectral density of 1.11 × 10–13 m/Hz1/2. When exciting the second-order plasmonic mode at λ = 780 nm we observe optical-power-induced frequency shifts of the mechanical oscillator. Our results show that novel functionality of plasmonic nanostructures can be achieved through coupling to engineered nanoscale mechanical oscillators.

Nano Lett.
Photonic Materials

Thijssen, R., Verhagen, E., Kippenberg, T., & Polman, A. (2013). Plasmon nanomechanical coupling for nanoscale transduction. Nano Lett., 13(7), 3293–3297. doi:10.1021/nl4015028