Achieving broad absorption band and high incident angles by stochastically-distributed oblique-flat-sheet metamaterial perfect absorbers.

In this work, we integrated a periodic seed layer and oblique deposition method to fabricate a stochastically-distributed oblique-flat-sheet metamaterial perfect absorber (MPA). Such design could increase its absorption bandwidth and tolerance to high angle-incidence due to the fact that various oblique flat sheets offer different resonance conditions while even a single oblique flat sheet could provide different optical paths for resonance. On the other hand, a seed layer could reduce uncertainty regarding to direct oblique deposition and provide abilities to manipulate the bandwidth of the MPA. We also setup a simulation model in the aids of Visual Basic Application and examined the absorption behavior of the MPA under TM and TE oblique incidence that could achieve high absorbance under 80° and 60° incidence, respectively. Finally, in measurement, the fabricated sample owns 65% absorbance within 80-250 THz and over 90% absorbance within 250-320 THz at x-polarization normal incidence; as for the y-polarization normal incidence, we could achieve overall 70% absorbance within 80-300 THz. The measured results reveal similar tendency compared to the simulated ones.