Terahertz Nonreciprocal Beam Deflection and Isolating Based on Magneto-Optical Anisotropic Metadevice

Active beam manipulation has significant potential in terahertz (THz) applications such as radar, wireless communication, and imaging, but they are still suffering from low efficiency and tunability. Here, by combining the gyroelectric semiconductor InSb with the anisotropic phase-gradient metasurface, a nonreciprocal beam manipulation device actively controlled by the magnetic field is demonstrated experimentally. Due to the diffractive angle-frequency dependence, the deflection waves are dispersed ranging from 35 degrees to 22.5 degrees in space corresponding to the frequencies of 0.7-1.1 THz. Importantly, two main functions of this device are developed for different polarization conversion and nonreciprocal transmission mechanisms. For the linear polarization (LP) to circular polarization output, this device modulates the diffraction efficiency from 2% to 70% by tuning the magnetic fields. For the LP to LP output, this device can separate the two orthogonal LPs in space, i.e., x- and y-LP, and switch them between 25 degrees and 35 degrees with different magnetic fields. Moreover, the metadevice achieves the nonreciprocal one-way transmission. This nonreciprocal beam manipulation mechanism and the related magneto-optical metadevice provide a new scheme for multifunctions combining beam steering, one-way transmission, polarization conversion, and magneto-optical modulation.