Proposing a novel structure for the implementation of a graphene-based tunable band pass/stop spatial THz filter

We propose a tunable multi-layer graphene surface plasmonic filter in the terahertz band. In this work, we can set the filter type, operation frequency, and pass/stop bandwidth by properly selecting the chemical potential of graphene. Also, higher-order filters are analyzed by cascading multiple filters. All filter parameters are controlled by tuning the graphene chemical potential to manipulate the Fermi level energy of graphene. The equivalent circuit of this device is modeled, and we find a way to design and simulate the proper filter based on the circuit model. Our proposed filter is independent of the polarization angle and the incident wave angle up to 60 degrees. The proposed tunable filter has great potential for spectroscopy, slow light, and filtering applications.