Polarization-Addressable Optical Movement of Plasmonic Nanoparticles and Hotspot Spin Vortices.

Spin-orbit coupling in nanoscale optical fields leads to the emergence of a nontrivial spin angular momentum component, transverse to the orbital momentum. In this study, we initially investigate how this spin-orbit coupling effect influences the dynamics in gold monomers. We observe that localized surface plasmon resonance induces self-generated transverse spin, affecting the trajectory of the nanoparticles as a function of the incident polarization. Furthermore, we investigate the spin-orbit coupling in gold dimers. The resonant spin momentum distribution is characterized by the unique formation of vortex and anti-vortex spin angular momentum pairs on opposite surfaces of the nanoparticles, also affecting the particle motion. These findings hold promise for various fields, particularly for the precision control in the development of plasmonic thrusters and the development of metasurfaces and other helicity-controlled system aspects. They offer a method for the development of novel systems and applications in the realm of spin optics.

Optimized array nanostructure for plasmonically induced motion force generation.

The growing demand to manipulate objects with long-range techniques has increasingly called for the development of techniques capable of intensifying and spatially concentrating electromagnetic fields with the aim of improving the electromagnetic forces acting on objects. In this context, one of the most interesting techniques is based on the use of plasmonic phenomena that have the ability to amplify and structure the electric field in very small areas. In this paper, we report the simulation analysis of a plasmonic nanostructure useful for optimizing the profile of the induced plasmonic field distribution and thus the motion dynamics of a nanoparticle, overcoming some limitations observed in the literature for similar structures. The elementary cell of the proposed nanostructure consists of two gold scalene trapezoids forming a planar V-groove. The spatial replication of this elementary cell to form linear or circular array sequences is used to improve the final nanoparticle velocity. The effect of the geometry variation on the plasmonic behaviour and consequently on the force generated, was analyzed in detail. The results suggest that this optimized plasmonic structure has the potential to efficiently propel macroscopic objects, with implications for various fields such as aerospace and biomedical research.