Design and simulation of band stop plasmonic filter with high quality factor and enhanced optical performance

Abstract

In this paper, we present the design and performance of a band-stop plasmonic filter incorporating a triangular resonator and a central circular cavity within a Metal-Insulator-Metal (MIM) waveguide configuration. The filter operates based on Surface Plasmon Polaritons (SPPs), which are excited at the metal-dielectric interface, allowing for a compact design with excellent optical performance. The filter design was optimized through a combination of numerical simulations using the Finite Difference Time Domain (FDTD) method and theoretical analysis. The simulation results indicate that the filter achieves a high-quality factor of 272 at a resonance wavelength of 818 nm and a cavity width (d) of 35 nm, significantly outperforming previously designed filters. Additionally, the paper presents a detailed comparison of the plasmonic performance of silver and gold, examining their effects on the quality factor, transmission spectrum, resonance wavelength, and overall optical performance. The results highlight that the choice of material plays a crucial role in optimizing the filter’s characteristics, as silver demonstrates a higher-quality factor and sharper resonance compared to gold. The filter's high-quality factor provides excellent wavelength selectivity and suppresses unwanted interference effectively, ensuring efficient performance. Moreover, the proposed structure exhibits a small full width at half maximum (FWHM) and tunable resonance wavelengths through precise control of geometric parameters such as cavity dimensions and resonator shape. These tunable characteristics make the filter highly suitable for advanced photonic applications, including optical filtering, high-speed communication systems, and biosensing. The significant results of this study confirm that the proposed plasmonic filter structure is a promising candidate for future nanophotonic systems, where high efficiency and precise wavelength control are essential.