Fabrication and optical properties of efficient multiband absorbers based on one-dimensional periodic metal-dielectric multilayers

Multiband absorbers comprised of one dimensional periodic Ag metallic thin layer and MoO3/SiO2 dielectric layer on a reflective Ag thick layer were fabricated by thermal evaporation and magnetron sputtering methods. Experimental results show that with the number of unit cell (N) increasing, the number of the absorption peaks increases accordingly and precisely equals N. For our fabricated devices with 14 nm thick Ag layer, 2 nm thick MoO3 layer, and 135 nm thick SiO2 layer, the integrated absorption efficiency over the wavelength range from 400 nm to 900 nm increases from 29.4%when N=1 to 57.2% when N=6, the trend of which is consistent with the calculation results. Moreover, measurements show that the absorption peaks are insensitive to the incident angles and polarizations. The multilayer absorbers were also fabricated on flexible polyethylene terephthalate substrates, which maintained their original absorption performances after bending for 1 000 times. The fabricated absorbers may have potential applications in areas like photovoltaics and thermal emission tailoring.