Tunable lateral and angular shifts of a reflected beam from a graphene-based structure

We discuss the lateral shift (LS) and the angular shift (AS) of a reflected Gaussian beam from the interface covered with a graphene sheet, which is modeled as an infinitesimally thin surface conductivity. In the two cases where the incident medium is optically rarer or denser than the refractive medium, the LS and AS are numerically analyzed for a TM-polarized beam by using the stationary-phase approach. It is found that both the LS and AS can be controlled by tuning graphene's chemical potential, the frequency or the angle of incidence of incident beam. In particular, when the incident medium is optically denser, since the total internal reflection takes place and the surface plasmon polaritons are excited, the larger AS can be achieved around the critical angle, the pseudo-Brewster angle or resonance angle. Also, a higher chemical potential can tune the directions of the LS (i.e., the positive or negative shifts). The results provide a way to tune flexibly the LS and AS by means of the graphene sheet.