Optomechanics with Silicon Nanowires by Harnessing Confined Electromagnetic Modes

Abstract

The optomechanical coupling that emerges in an optical cavity in which one of the mirrors is a mechanical resonator has allowed sub-Kelvin cooling with the prospect of observing quantum phenomena and self-sustained oscillators with very high spectral purity. Both applications clearly benefit from the use of the smallest possible mechanical resonator. Unfortunately, the optomechanical coupling largely decays when the size of the mechanical system is below the light wavelength. Here, we propose to exploit the optical resonances associated to the light confinement in subwavelength structures to circumvent this limitation, efficiently extending optomechanics to nanoscale objects. We demonstrate this mechanism with suspended silicon nanowires. We are able to optically cool the mechanical vibration of the nanowires from room temperature to 30-40 K or to obtain regenerative mechanical oscillation with a frequency stability of about one part per million. The reported optomechanical phenomena can be exploited for developing cost-optimized mass sensors with sensitivities in the zeptogram range.

Biosensors based on nanomechanical systems

“…Optical detection is bulky, thus more suited for bench-top equipment, but offers an enormous flexibility in the fabrication of nanomechanical systems that gives space for the development of novel concepts. For instance, the coupling between light and mechanics that occurs in optical cavities in which one of the mirrors is a flexible mechanical system opens the door for realizing novel optomechanical biosensors with enhanced performance [40][41][42] .…”

Nonlinear dielectric optomechanical metamaterials

“…[7][8][9][10][11][12][13][14][15] Optical forces can also be harnessed for actuation of nanophotonic devices. [16][17][18][19] Indeed, the convergence of nanophotonics and nanomechanics through optical forces presents enormous potential for all-optical operation of nanomechanical systems, reconfigurable and ultrawidely tunable nanophotonic devices, and novel nonlinear and selfadaptive photonic functionalities.…”

A universal and ultrasensitive vectorial nanomechanical sensor for imaging 2D force fields

“…In this article, we expose a novel ultrasensitive measurement technique going beyond scalar measurements and permitting to directly image vectorial 2D force fields. It is based on a singly clamped nanowire (NW) which can oscillate along two perpendicular transverse directions [18,[20][21][22][23][24]. Its vibrating extremity is immersed in the force field under investigation while its 2D-Brownian motion is optically detected and reconstructed in realtime.…”

“…In this work we investigate situations where the force field experienced by the NW (here of electrostatic origin) instantaneously follows -on mechanical timescales-the change in the NW position. Delays in the establishment of the force [23,27,28] could be treated with the same formalism [29]. The force experienced by the NW can be linearized as…”