Bifunctional metasurface for polarization-controlled beam steering and excitation of spoof surface plasmon polariton

Based on the combination of propagation phase with geometric phase, to the best of our knowledge, a new reflective metasurface which can control the direction of reflected waves and excite spoof surface plasmon polariton (SSPP) simultaneously is proposed and numerically demonstrated fur the circular polarization incident waves. The incident waves can be converted into SSP with longitudinal wave vector k(x). = 1.2 k(0) or anomalously reflected with reflection angle theta(r) = 13.9 degrees under the illumination of the left or the right circular polarization beam, respectively. The respective converting efficiency of the left and right circular polarization can reach up to 70% and 82% at the frequency of 0.3 THz. Our study may open up new routes for polarization-related antennas, detectors and other practical terahertz devices.