Circular Polarization-Dependent Wavefront Control of Plasmons on Graphene

In this letter, we propose a method to control the wavefront of the graphene plasmons through changing the polarization direction of the circular polarized incidence. Illuminated by the circular polarized incident light, the plasmons are launched through the resonances of a column of nanoantenna pairs beneath graphene. By properly controlling the separation and orientation of antennas in each pair, the propagation direction of plasmons wavefront is no longer perpendicular to the column and the launching angle is also dependent on the circular polarization of incident light. By combining the nanoantenna arrays with their mirroring arrays, two-dimension biconvex or biconcave plasmon lens can be realized. Furthermore, the launching angle can be controlled by the incident wavelength, the phase gradient between adjacent nanoantenna pairs, and the graphene Fermi level. The proposed scheme may provide new possibilities in engineering plasmons wavefront on graphene through launching procedure.