Tri-band polarization convertor based on the multi-layer metamaterial

In this paper, a tri-band polarization convertor has been investigated both theoretically and numerically based on a multi-layer metamaterial which composed of an interlayer double-rod resonator and two S-shaped resonators. All numerical simulations have been done with the CST Microwave Studio. In the proposed metamaterial, three asymmetric transmission bands have been achieved at infrared wavelengths of 1.2–1.87, 1.87–2.94, 2.94–3.53 μm. In addition, the physical mechanism of broadband polarization convertor with asymmetric transmission has been investigated at specific wavelengths of 1.45, 2.38 and 3.36 μm. It has been demonstrated that Fabry–Perot-like cavity in the proposed metamaterial can broaden the bandwidth and improve the conversion efficiency. Moreover, the performance and concrete bandwidth of polarization convertor can be successfully controlled by adjusting the related parameters. According to the simulation results and analyses, the designed metamaterial could be functioned as polarization convertor or isolator with a broad bandwidth.