Ultra-Wide-Band Band-Pass Filters Using Plasmonic MIM Waveguide-Based Ring Resonators

In this letter, different types of plasmonic ultra-wide band band-pass filters (UWB-BPFs) have been studied and numerically analyzed. The filters have been designed based on the angular ring resonators (ARRs) and square ring resonators (SRRs) connected with a coupled feed line. The UWB can be realized by suitably adjusting the coupling gaps both sides of the resonator. Based on the ideal characteristics of the proposed ARRs and SRRs, all miniaturized UWB-BPFs are operating at THz frequencies. Multiple transmission zeros are generated to improve the selectivity of the filter. All simulated results have been studied using CST Microwave studio suite. The transmission performance is explained by the resonance condition, which agrees well with the numerical simulation or theoretical calculation. This letter provides a promising application for plasmonic UWB-BPFs and plasmonic integrated optical circuits.