High-Quality-Factor, Compact Nanoplasmonic Filter Utilizing Graphene Metasurface at Near-Infrared Range

A plasmonic reflective filter (PRF) based on monolayer graphene and four nanoscale cylindrical silica grooves inside a silver film is suggested and theoretically analyzed. The designed filter has a dual-band reflection and absorption spectra with a near-unity absorption value at resonance wavelengths located in near-infrared region. Furthermore, the two reflection dips can be tuned via harnessing graphene chemical potential. Application of subwavelength metallic structure as well as graphene layer contributes to the increased light–matter interactions and reinforces the light confinement in the nanoscale regions in the cylindrical grooves. As a result, near-zone electric field is highly enhanced and leads to the strong optical absorption of the filter. Also, the optical response of the proposed PRF is independent from the polarization of the incident light due to the symmetrical geometry of the structure. The suggested filter can be utilized in photonic integrated circuits.