High-performance polarization-controlled terahertz spoof surface plasmon polaritons metacoupler

In this paper, a linear polarization-controlled (LPC) spoof surface plasmon polaritons (SSPPs) meta-coupler with high efficiency and directionality is proposed and demonstrated in the terahertz (THz) regime. By changing the polarization (TE or TM polarization) of the incident electromagnetic (EM) waves, the corresponding SSPPs can be directionally excited towards opposite directions. The meta-coupler is composed of a coupling metasurface (CM) and two propagating metasurfaces (PMs) on both sides of CM. Under the illumination of specified polarization Gaussian beam, the unit cells of the CMs have the similar electric field distribution with that of PMs, which can realize a smooth and efficient transition between the surface waves and SSPPs. The respective excitation efficiency of the TE and TM polarization can reach up to 87% and 90% at the frequency of 0.355 THz. Besides, the PMs are designed to support the propagation of the specified TE or TM mode SSPPs. This guarantees a relatively high directionality (> 24 dB) in the frequency range of 0.325-0.375 THz. Our study may open up new routes for polarization-related antennas, detectors and other practical THz devices.