Terahertz polarization converter and one-way transmission based on double-layer magneto-plasmonics of magnetized InSb

In this work, we investigate the nonreciprocal circular dichroism for terahertz (THz) waves in magnetized InSb by the theoretical calculation and numerical simulation, which indicates that longitudinally magnetized InSb can be applied to the circular polarizer and nonreciprocal one-way transmission for the circular polarization THz waves. Furthermore, we propose a double-layer magnetoplasmonics based on the longitudinally magnetized InSb, and find two MO enhancement mechanisms in this device: the magneto surface plasmon resonance on the InSb-metal surface and Fabry-Pérot resonances between two orthogonal metallic gratings. These two resonance mechanisms enlarge the MO polarization rotation and greatly reduce the external magnetic field below 0.1T. The one-way transmission and perfect linear polarization conversion can be realized over 70dB, of which the transmittance can be modulated from 0 to 80% when the weak magnetic field changes from 0 to 0.1T under the low temperature around 200K. This magnetoplasmonic device has broad potential as a THz isolator, modulator, polarization convertor, and filter in the THz application systems.