Optical Ultra-Wideband Nano-Plasmonic Bandpass Filter Based on Gap-Coupled Square Ring Resonators

In this work, an ultra-wideband (UWB) optical bandpass filter (BPF) based on nanoplasmonic structure is designed and thoroughly analyzed. The proposed BPF encompasses asymmetric metal-insulator-metal (MIM) slot waveguide that incorporates a gap-coupled series parallel square ring resonators (SRRs). characteristic parameters of the MIM are analyzed with full-wave analysis conformal mapping technique (CMT) using CAD simulation software. These include normalized propagation constant, length, impedance. UWB feature mainly dictated by coupling gaps combine feed line resonators. Increasing sequential number coupled enhances design. Two structures three five presented to illustrate characteristics within 1235.74-1942 nm, 1340-2200 nm ranges, respectively. both cases, return loss shown be higher than 10dB. in work has potential replace narrow-bandwidth devices involved multi-band transmission systems high-density photonic integrated circuits. outcomes research contribute advancement technology for next-generation communication photonics.