Enhance of the absorption and bandwidth based on a ultra-thin tungsten structure metamaterial absorber in 400–1500 nm range

Abstract

In this paper, an ultra-thin metamaterial absorber with simple structure strategy is proposed and verified in the 400–1500 nm band. A 0.2μm thick metamaterial absorber with silver disk array is proposed and measured. Three absorption peaks (The absorption amplitudes are: 90%, 75%, and 85%) are obtained at resonance wavelengths 612nm, 1100nm, and 1228nm, respectively. It should be noted that these achieved absorption bandwidths are relatively small. In order to enhance the absorption rate and bandwidth, an ultra-thin tungsten structure absorber with the same structural parameters is also verified and measured. Four absorption peaks (The absorption amplitudes are: 98%, 88%, 92%, and 95%) are obtained at resonance wavelengths 614nm, 741nm, 1072nm,and 1312nm, respectively. The average absorbance of the tungsten structure absorber is also higher than that of the silver structure absorber. These absorption peaks are excited by the electromagnetic resonance modes of the absorber and the higher average absorbance is due to the field dissipation effect of the tungsten layer. The proposed ultra-thin tungsten structure absorber reveals both high absorption rate and large absorption bandwidth.