Frequency-region quantitatively adjustable Si perfect absorbers

Abstract

In this work, we demonstrate a tri-band perfect absorber with the maximal absorptance of 97% achieved in an ultra-thin silicon film metasurface (thickness, 60 nm, ∼λ/10). Particularly, the resonant absorption peaks are observed to be quantitatively adjustable in the frequency region via tuning the cavity size in the silicon metasurface. Simultaneously, the absorption efficiency remains at a high level for the tri-band spectrum. These features suggest a novel way to artificially manipulate the operation wavelength and hold potential applications in coloring displayer, filtering, hot-electron related optoelectronics.