Phase modulation of output light by planar metallic-dielectric array with electro-optical material

A structure of active planar metallic-dielectric array is proposed to manipulate the propagation of light beam by tuning the phase of output light. The dielectric in the array is set as an electro-optical material so that the refractive index can be changed by applied voltage based on the electro-optical effect. While the light propagates through the array, the surface plasmon polaritons (SPPs) are excited and the waveguide modes with variant propagation constants are formed in the dielectric regions to provide desired phase retardations. The finite-difference time-domain (FDTD) method is used to numerically simulate the tunable phase characteristic of output light. The results show that, by adjusting the applied voltage on the dielectric regions, the angle compensation and beam focusing phenomena can be easily implemented, and the tunability of focal length is investigated in detail as an example. It is helpful for the design of actively-controlled plasmonic devices.