Tunable plasmonic band-pass filter based on Fabry-Perot graphene nanoribbons

A plasmonic band-pass filter (BPF) structure is designed and proposed in this research. The filter structure includes two graphene nanoribbon (GNR) waveguides laterally coupled to three perpendicular GNRs that forms a Fabry-Perot resonator (FPR). The transmission spectrum of the proposed structure can be tuned in an efficient and flexible fashion by making adjustments on the overall geometrical structure and its chemical potential, as well. Geometry can be modified in the design step, even as a real-time controlling voltage can be applied as a chemical potential tuner. The coupling distances between GNR waveguides and GNRs of the FPR and also coupling distances among GNRs of FPR themselves strongly affect the transmission spectrum and bandwidth characteristics of the BPF. Transmission spectrum with one, two, or three peaks can be achieved by adjusting the distances between GNRs of the FPR, even as other geometrical adjustments and/or chemical potential tuning shifts the spectrum to the desired frequency range. The results achieved by 3D finite-difference time-domain (3D-FDTD) method verify the capability of the proposed structure to be applied in applications used in plasmonic and nano-optoelectronics devices.