An ultra-wideband bandstop plasmonic filter in mid-infrared band based on metal-insulator-metal waveguide coupled with an hexagonal resonator

An ultra-wideband band-stop plasmonic filter (UWB-BSF) in mid-infrared (MIR) range based on metal–insulator–metal (MIM) waveguide coupled with a hexagonal resonator is proposed this work. Using RSoft CAD commercial software, the designed BSF numerically and theoretically investigated by 2D Finite-Difference Time-Domain method. To enhance BSFs system mid-infrared, obtaining ultra-wide bandgap width (UWB) maximum passband transmission at left right of high value rectangular coefficient, we increase number cavities. Hence, resonators controls filtered wavelength system. In case two hexagonal-shaped resonators, Fano resonance appears sides bandgap, forming U-shaped spectrum, which very helpful for improving performance filter. Furthermore, changing geometric parameters cavities shifted toward near-infrared (NIR) band. The center nano-stop-band adjustable varying structure. This device operates ranges. With larger tunable performance, nanostructure provides an advantageous application integrated circuits broadband transmissions.