Design of dual-wideband bandstop MIM plasmonic filter using multi-circular ring resonators

Abstract

A dual-wideband bandstop plasmonic filter in Near-Infrared (NIR) and Mid-Infrared (MIR) wavelength ranges based on Metal-Insulator-Metal (MIM) waveguide coupled with multi-circular ring resonators is designed. As the number of circular rings is increased, the stop wavelength bands are broadened and the extinction ratio (ER) is improved. Also, the stop wavelength ranges can be adjusted to the desired bands by changing the insulator relative permittivity. Because achieving any proper insulator relative permittivity may be difficult with the general dielectrics, the insulator region is realized by a nanocomposite medium. In this way, insulator region is designed by a polymeric medium, poly-methyl-methacrylate (PMMA), with a random distribution of spherical Ag nanoparticles. The desired relative permittivity of the insulator region and consequently, the proper stop wavelength ranges are achieved by changing the filling fraction of Ag nanoparticles. Therefore, the stop wavelength bands can be tuned with the number of circular ring resonators and guest nanoparticles filling fraction. The designed structure has potential to be employed in IR spectroscopy and broadband communications. • A dual-wideband bandstop plasmonic filter in Near-Infrared (NIR) and Mid-Infrared (MIR) wavelength ranges is designed. • As the number of circular rings is increased, the stop wavelength bands are broadened and the extinction ratio is improved. • The stop wavelength ranges can be adjusted to the desired bands by changing the insulator relative permittivity. • Insulator region is designed by a polymeric medium with a random distribution of spherical Ag nanoparticles. • The stop wavelength bands can be tuned with the number of circular ring resonators and guest nanoparticles filling fraction. The structural dimensions of the filter are considered as w = 80 nm, d = 40 nm, h = 40 nm, R in = 95 nm, R out = 150 nm and t = 55 nm.