A highly directional metamaterial-based terahertz circulator that does not require an external magnetic field

Abstract Circulators, as passive non-reciprocal devices, have excellent potential for application in wireless communication and radar-signal processing. However, the construction of terahertz (THz)-frequency circulators is extremely difficult. Here, an electromagnetic matching model for metamaterials is proposed to support the design of a THz circulator with a wider operating bandwidth. The resulting circulator can work without an external magnetic field in the THz frequency range. The best isolation of this THz circulator is 20.9 dB, and its maximum directionality is 16.6 dB. These results validate a new method for the design of metamaterial-based THz devices.