Optical matter based on graphene surface plasmons.

In this work, we have proposed a graphene planar structure as an optical binding device of dielectric nanoparticles. Surface plasmons (SPs) on a graphene sheet, generated thanks to the near field scattering of the incident plane wave by the nanoparticles placed close to the graphene sheet, act as a powerful intermediary for enhancing the optical force between nanoparticles to organize the particle structure at length scales comparable with the plasmon wavelength, i.e., at the light sub-wavelength scale. In particular, we have paid attention to the formation of one-dimensional arrays of nanoparticles. Our results show that both the equilibrium separation between particles and the energy potential binding depend on the number of particles forming the array and that the former tends to the plasmon wavelength (the array constant) for a number of particles large enough. We have obtained simple analytical expressions that explain the main results obtained by using the rigorous theory. Our contribution can be valuable for the knowledge in the low-frequency optical binding framework, from terahertz to far-infrared spectrum.