Plasmomechanical actuation at the nanoscale activated by NIR radiation

• A novel plasmomechanical actuator is proposed, integrating a nanodipole antenna and coupled micro-nanocantilevers. • Near-infrared (NIR) light at 1.55 μm induces opto-electromechanical (OEM) actuation via capacitive coupling. • COMSOL Multiphysics simulations model both desired OEM and parasitic optothermomechanical (OTM) responses. • The optimized design achieves a responsivity of 0.67 nm/mW, comparable to state-of-the-art NIR detectors. • Fabrication feasibility of high-slenderness nanocantilevers is experimentally validated using FIB nanolithography. The design of a plasmomechanical actuator based on an optical nanodipole antenna integrated in the overlapped free moving end of two micro-nanocantilevers is presented here. The static steady state deflection of the cantilevers, which defines the actuator response, is produced by means of two transduction phenomena activated by a continuous power NIR illumination: a desired opto-electromechanical (OEM) mechanism, in which the cantilevers are mutually attracted directly by the electrostatic force induced in the nanodipole feed gap, and a non-desired parasitic opto-thermomechanical (OTM) mechanism associated to the bimetallic effect induced by the optical heating of the structure. COMSOL Multiphysics has been chosen to carry out a design of the actuator based on an optimized optical response of the nanodipole antenna to the 1.55 μm wavelength radiation. COMSOL simulations have been also performed to evaluate the parasitic OTM response and the responsivity, defined as the OEM signal per unit radiation power. Predicted responsivity values of 0.67 nm/mW are of the same order of magnitude as in similar state-of-the-art transducers.