Tunnelling effects induced transparent polarization manipulation

We proposed, designed and fabricated a three-layer metamaterial consisting of two layers of electrically spilt ring resonators (SRRs) and a layer of the subwavelength metal mesh symmetrically sandwiched between the two SRR layers. The numerical simulations and experimental measurements revealed that the linear-to-circular, linear-to-elliptical and linear-to-linear polarization controls can be accomplished by simply altering the polarization angle of incident waves. This transparent polarization conversion/rotator is related to the tunnelling effects of electromagnetic (EM) waves for both incident polarizations. The physical mechanism of tunnelling effect is also investigated both numerically and experimentally, and results have shown that the high- ε SRR layer facilitates the EM waves to propagate through the metal mesh layer without attenuation. In addition, the magnetic field distribution in the structure is analysed to further illustrate this tunnelling phenomenon. The thickness of this polarization device is ultra-thin compared with the wavelength, which provides a new way for designing the miniaturized and light weight quarter wave plates or other polarization manipulation devices.