Plasmonic linear nanomotor using lateral optical forces

6 pags., 4 figs.
Optical force is a powerful tool to actuate micromachines. Conventional approaches often require focusing and steering an incident laser beam, resulting in a bottleneck for the integration of the optically actuated machines. Here, we propose a linear nanomotor based on a plasmonic particle that generates, even when illuminated with a plane wave, a lateral optical force due to its directional side scattering. This force direction is determined by the orientation of the nanoparticle rather than a field gradient or propagation direction of the incident light. We demonstrate the arrangements of the particles allow controlling the lateral force distributions with the resolution beyond the diffraction limit, which can produce movements, as designed, of microobjects in which they are embedded without shaping and steering the laser beam. Our nanomotor to engineer the experienced force can open the door to a new class of micro/nanomechanical devices that can be entirely operated by light.
This work was supported by JST PRESTO grant JPMJPR15PA, Japan, and JSPS KAKENHI grant nos. JP19H02533 and JP19H04670 in Scientific Research on Innovative Areas “nanomaterial optical manipulation.” Preliminary studies were performed at Imperial College London, under support of the EPSRC Active Plasmonics Programme (EP/H00917/2). P.A acknowledges Ramon y Cajal Fellowship RYC-2016-20831 and MICINN project PGC2018- 096649-B100. M.R. acknowledges support from the Royal Society and the Wolfson Foundation.