Design of a Single-Mode Plasmonic Bandpass Filter Using a Hexagonal Resonator Coupled to Graded-Stub Waveguides

In this paper, a plasmonic filter based on metal-insulator-metal (MIM) configuration is proposed. It uses a hexagonal nano-resonator (HNR) coupled to multi-stub waveguides (MSWs) from both sides. The metal and insulator of the proposed plasmonic filter are silver and air, respectively. Finite difference time domain (FDTD) method is used for numerical simulations. The simulation results indicate that the proposed filter has a single transmission peak at 987nm with a maximum transmission equal to 67%. The advantages of the proposed structure are a resonance wavelength with high transmission peak and flat transmission spectrum out of the transmission resonance wavelength.The Drude-Lorentz model (DLM) is used for numerical characterization of silver in the proposed structure. Such a model is thereafter compared with Drude and Palik models. To investigate the effect of different structural parameters of HNR and multiple stubs on their transmission spectrums, such structures are simulated by sweeping different parameters. Considering these features, the proposed filter has the potential to be employed in various plasmonic devices such as demultiplexers for optical communication purposes.