Broadband THz reflective polarization rotator by multiple plasmon resonances.

We demonstrate a metamaterials-based THz broadband polarization rotator which is able to rotate linearly polarized THz wave by 90 degree within a wide frequency range (0.44 to 0.76 THz). The device is characterized both theoretically and experimentally. Analyses show that the multiple-plasmon-resonance is the key for the broadband feature and the phase-shift difference of the two reflection components is critical for the polarization conversion. The approach demonstrated in the work can be useful for constructing building blocks for THz polarimetry.