Tunable terahertz dual-band band-stop filter based on surface magnetoplasmons in graphene sheet array

Magnetically tunable terahertz dual-band band-stop filters are proposed based on the surface magnetoplasmons of graphene. The magnetoplasmons of a graphene rectangular sheet array can be attributed to the combination effects of the two edge plasmons along the length and width directions. Under external magnetic field the two plasmonic resonances are respectively blue-shifted and red-shifted, leading to different dips in the vertical transmission spectrum through the graphene array. Following this mechanism, narrow-band and wider-band band-stop filters with dual stop bands are theoretically obtained in composite structures consisting of graphene sheet array layers and semiconductor substrate layer. The influence brought by structural parameters and the chemical potential of graphene on the filtering performance are analyzed. Numerical results show the center frequencies of the two stop bands of the filters can be efficiently tuned by the intensity of the magnetic field.