Experimental demonstration of a Fano resonant hybrid plasmonic metasurface absorber for the O and E bands of the optical communication window

Abstract

Plasmonic metasurface absorbers are capable of absorbing the incident light at wavelengths corresponding to the excitation of Fano resonant modes. Absorption of the incident light is possible because of its confinement near the edges of the plasmonic nanostructure. Confinement of light takes place because of the coupling of superradiant and subradiant modes near the edges of the plasmonic metasurface. Superradiant and subradiant modes are excited for the oblique angle incidence of transverse magnetic (TM)-polarized light. The incidence of TM-polarized light supports the excitation of surface plasmon modes at the metal–dielectric interface. For the oblique angle incidence, surface plasmon modes couple with the incident light and generate the superradiant and subradiant modes near the plasmonic metasurface. We experimentally demonstrate the absorption of near-infrared light in the O and E optical communication band by a one-dimensional (1D) hybrid plasmonic metasurface. A low-cost, and flexible, 1D hybrid plasmonic metasurface absorber (HPMA) was obtained by extracting an Ag-coated, flexible, and 1D patterned polycarbonate layer from a digital versatile disc (DVD). The DVD consists of an Ag layer sandwiched between two 1D patterned polycarbonate layers. A large-area HPMA of 3cm2 in size was fabricated for optical characterization. Control experiments on the variation of the angle of incidence of light were performed to achieve the maximum light absorption of  79%. The effect of transverse electric (TE)- and TM-polarized light on the HPMA was studied. The effect of the thickness of the polymer layer on the HPMA, and per unit change of refractive index (RIU) of the analyte medium, were also investigated. HPMA supports refractive index sensing characteristics with a maximum sensitivity of 954 nm/RIU. Electric field profiles at different incidence angles were simulated using the finite element method on COMSOL Multiphysics software to explain the underlying physics of Fano resonance. HPMA can be used to develop cost-effective photonic devices such as sensors, spectral filters, photodetectors, heat-absorbing protective photonic covers, etc.