linearly polarized converters for reflected and transmitted waves based on double-split ring resonator

We propose and demonstrate the linearly polarized converters for reflected and transmitted waves based on a double-split ring resonator (dsrr). for reflective polarization converter, the three-layered metamaterial structure can rotate the polarization state of incident linearly polarized wave into its orthogonal one. the calculated results indicate that the polarization conversion ratio of reflective polarization rotator can reach unity (99.99%) at the resonant frequency. for transmissive polarization rotator, we propose a multi-layered metamaterial structure at terahertz frequencies which exhibits the incident y-polarized wave can be thoroughly and perfectly converted to the x-polarized output wave over the entire frequency range. the numerical simulation and theoretical calculation indicate that polarization conversion ratio of the y-polarized wave can be higher than 99.98% at the frequency range from 0.42 to 1.59 thz. additionally, we investigate the polarization rotation properties based on optical activity and ellipticity. specifically, the proposed structure can achieve simultaneously a multi-band 90o polarization rotation angle and an extremely low dispersion (lower than 0.25o, absolute value). the physical mechanism of polarization conversion is also analyzed based on the electronic field distribution at the resonance frequency.