Numerical investigation of plasmonic metasurfaces for improved MIR absorption

Plasmonic metasurfaces represent a new type of metamaterials which present a large variety of applications. An important use of these structures is focused on absorption increase in the mid infrared domain in a way that one... [ view full abstract ]

Plasmonic metasurfaces represent a new type of metamaterials which present a large variety of applications. An important use of these structures is focused on absorption increase in the mid infrared domain in a way that one can obtain approximately total absorption on narrow wavelengths intervals. Essentially, the absorption as well as the emissivity of a plasmonic microstructured metasurface can be precisely controlled in a well defined spectral domain by the geometrical parameters of the plasmonic elements of the array [Appl. Phys. Lett. 100, 203508 (2012), Phys. Rev. Lett. 107, 045901 (2011)]. 

We present a class of plasmonic metasurfaces modeled for achieving an almost total absorption on narrow wavelengths intervals in MIR domain. Our metamaterial is obtain by micro-structuring an array of  gold (Au) pillars of 200 nm hight on a 200 nm thick silicon (Si) deposed on a thin gold film (200 nm). We performed 3D numerical investigation using finite differential time domain (FDTD) investigating the dependence of the absorption spectrum as a function of the metasurface geometrical and material parameters (Fig.1). We conclude that this type of structure improves the electromagnetic field absorption almost to unitary values for several well defined narrow wavelengths intervals.