Amplitude- and Phase-Controlled Surface Plasmon Polariton Excitation with Metasurfaces

Surface plasmon polaritons (SPPs) have shown high potential for various applications in various fields, ranging from physics, chemistry, and biology to integrated photonic circuits due to their the strong confinement of light to the metal surface. Exciting an SPP from a free-space photon in a controllable manner is an essential step toward more complex and integrated applications. Methods for coupling photons to SPPs are numerous, but in order to control the amplitude and phase of an SPP, most of these methods require bulky or multiple optical components or sensitive adjustments that are difficult to control. Here we present a novel approach for an independent control of the amplitude and phase of an SPP excited by a normally incident beam using a metasurface. The full control in amplitude and phase is achieved via the polarization state and polarization orientation angle of the electrical field of the incoming light. We experimentally demonstrate the functionality of such a metasurface consisting of periodic nanoantennas for the excitation of SPPs at a metal-dielectric interface. Our approach opens up new ways for coherently controllable integrated plasmonic circuits that can be used in conjunction with fast dynamic polarization modulation techniques. (Figure Presented).