Broad band absorber based on cascaded metamaterial layers including graphene

In order to extend the absorption band of the metamaterial with tilted graphene sheets, we use cascaded metamaterial layers and study the dependence of absorption on the structure parameters. The absorption spectra can be obtained through the transfer matrix method that we derive from the special metamaterial. The individual band of these metamaterial layers could be adjusted by modifying their geometrical and electrical parameters. We find that the absorption bandwidth of cascaded structure can be much increased with the number of layers increasing.