Shape-dependent absorption characteristics of three-layered metamaterial absorbers at near-infrared

We experimentally demonstrate the absorption properties of designed metamaterial absorbers in the near-infrared wavelength regime. For the rectangular-shaped case, we demonstrate its polarization dependent absorbance at various incident angles. For each polarization, the absorbance is insensitive to the incident angle (up to 60 degrees) and a maximum absorbance of 0.95 is obtained. Of particular interest we experimentally observe an absorption peak corresponding to a high-order resonance at 60 degrees with an absorbance of 0.68 excited by the TM polarization. For the square-shaped case, we show its polarization-independent absorption property. A maximum absorbance around 0.65 is achieved at normal incidence and it remains high for incidence angles up to 50 degrees. (C) 2011 American Institute of Physics. [doi:10.1063/1.3573495]