Design of a simplified plasmonic filter to enhance its capability in controlling light propagation
摘要
In this paper, the performance of a plasmonic filter based on a metal-air waveguide containing a washer-shaped resonator is analyzed. Influence of geometric design parameters, such as the washer width d, gap width g, outer washer radius, and material composition on the transmission, reflectivity, and absorbance have been investigated. The results show that increasing d results in a red shift in the transmission spectrum and enhances resonant coupling, while decreasing g reduces the optical coupling and shifts the spectrum toward shorter wavelengths. The full width at half-maximum (FWHM) and the quality factor are also highly dependent on the washer radius and structural length, highlighting the trade-off between the transmission efficiency and resonance resolution. The proposed filter achieves a transmittance exceeding 70%, a transmittance bandwidth of 10 nm, and a quality factor of up to 70. Furthermore, the comparison of silver and gold using the Drude model showed that silver offers higher transmission efficiency and better quality factor compared to gold, making it an ideal choice in high-performance optical filtering applications. These results provide a solid basis for the design and optimization of tunable plasmonic devices in the fields of sensing, filtering, and energy absorption.