Design and Analysis of Infrared Tunable All-Optical Filters Based on Plasmonic Hybrid Nanostructure Using Periodic Nanohole Arrays

A tunable high transmission optical bandpass filter based on a plasmonic hybrid nanostructure, composed of a periodic array of nanocircles and nanoholes combining two isolated waveguides is introduced in this paper. The presented design improves the coupling, which results in a higher transmission peak. To study the filtering operation, different topologies are investigated. The transmission properties and the resonance wavelengths are adjusted by sweeping various geometrical parameters. A multimode spectrum for each of the topologies is obtained. A tunable bandgap and bandwidth can be obtained by adjusting the refractive index of the periodic nanostructure. We have reached a maximum quality factor and a small full width at half-maximum bandwidth with the maximum transmission values greater than 80%. The advantages of the presented structures which include the benefits of both plasmonic and periodic nanostructures are tunability, high detection resolution, and integrability at the nanoscale for optical applications.