Asymmetric transmission modular design via direction-dependent absorption of spoof surface plasmon polaritons

A method of achieving asymmetric transmission is proposed by means of the propagation direction-dependent absorption of spoof surface plasmon polaritons (SSPPs). In this letter, trapezoidal wire arrays which act as absorbers have been combined with cutting metal wires which act as polarization rotators. By combining trapezoidal wire arrays with polarization rotators, the metamaterial can exhibit different properties according to the direction of the incident wave, thereby achieving asymmetric transmission. Incident waves can be efficiently converted to the SSPPs by trapezoidal wire arrays, and their propagation and/or absorption can be controlled by engineering the spatial dispersion of k-vector. Moreover, polarization rotators based on cutting metal wires can customize the polarization rotation performance by changing the length of the metal wire. The simulated and measured results verify the asymmetric transmission effect and design method. The proposed asymmetric transmission structure can be applied in electromagnetic devices for linearly polarized wave or polarization control. Compared with chiral metamaterial structures, this work improves the design customizability and efficiency as well as provides an alternative method of designing asymmetric transmission. In addition, the framework expands the application prospect of asymmetric transmission and builds a bridge from SSPPs to asymmetric transmission, facilitating the asymmetric transmission integrated with other SSPPs devices.