Figure 3

(a) Schematic of the LIPSS imprinted plasmonic gap metasurfaces and principle of operation for the polarizer, i.e., polarization sensitive perfect absorption, green arrows present the x polarization and blue arrows the y polarization. (b) Dimensions definition in the LIPSS imprinted metasurface. (c) Absorption spectra under normal incidence for two LIPSS imprinted, metal-insulator-metal, plasmonic gap metasurfaces of different insulating cavity thickness, one thinner with thickness \(H=140\) nm (top panel) and one thicker with thickness \(H=440\) nm (bottom panel) in the wavelength range \(\lambda =\)  [1–4] μm for both polarizations, i.e., the electric field being normal to the top layer nanowires, E = \(E_x\) (dark- and light-green) and the electric field being parallel to the top layer nanowires E = \(E_y\) (dark- and light-blue). (d) Distribution of the scattered absolute values of the electric and magnetic field in the selected wavelength points of the spectral response, points 1 to 6, for both polarizations shown in (c). Notice that the y-coordinate starts at \(y=0\), at the interface between the gold layer and the dielectric layer and increases towards the Ni nanowire. (e) Distribution of the power loss density showing the plasmonic losses predominately in the Ni nanowire and then in the Au back-reflector.