Beam bending via plasmonic lenses.

We have designed and characterized three different types of plasmonic lenses that cannot only focus, but can also bend electromagnetic (EM) waves. The bending effect is achieved by constructing an asymmetric phase front caused by varying phase retardations in EM waves as they pass through a plasmonic lens. With an incident wave normal to the lens surface, light bends up to 8° off the axial direction. The optical wave propagation was numerically investigated using the finite-difference time-domain (FDTD) method. Simulation results show that the proposed plasmonic lenses allow effective beam bending under both normal and tilted incidence. With their relatively large bending range and capability to perform in the far field, the plamsonic lenses described in this article could be valuable in applications such as photonic communication and plasmonic circuits.