We propose a new graphene-based THz circulator. It consists of a circular graphene resonator and three graphene nanoribbon waveguides of W-geometry placed on a dielectric substrate. Surface plasmon-polariton waves propagate in the waveguides. The nanoribbon excites in the resonator dipole resonance. Nonreciprocity of the device is defined by nonsymmetry of the conductivity tensor of the magnetized graphene. Numerical simulation example present a circulator which operates at a central frequency of 7.5 THz has the bandwidth 4.25% for isolation −15 dB, insertion loss −2.5 dB. Applied DC magnetic field is 0.56 T and Fermi energy of graphene ${ϵ}_F=0.15$ eV. The frequency band of the circulator can be enlarged at the expense of higher DC magnetic field and its central frequency of operation can be tuned by varying resonator radius, nanostrips width, distance between the resonator and the waveguide. Fermi energy allows one to control dynamically the circulator responses.

我们提出了一种新的基于石墨烯的太赫兹环行器。它由一个圆形的石墨烯谐振器和三个W形的石墨烯纳米带波导放置在介电基片上组成。表面等离子体激元极化波在波导中传播。纳米带在谐振器偶极子谐振中激发。器件的不可逆性是由磁化石墨烯的电导率张量的非对称性定义的。数值模拟示例显示了一个以7.5 THz中心频率运行的循环器，其隔离度带宽为4.25％，隔离度为-15 dB，插入损耗为-2.5 dB。施加的直流磁场为0.56 T，石墨烯的费米能${ϵ}_F=0.15$ eV。可以以较高的直流磁场为代价来扩大环行器的频带，并且可以通过改变谐振器半径，纳米带宽度，谐振器与波导之间的距离来调整其工作中心频率。费米能量使人们可以动态地控制循环器的响应。