Absorption enhancement in double-layer cross-shaped graphene arrays

In this work, we put forward a wavelength tunable absorber which consists of periodic double-layer cross-shaped graphene arrays in the far infrared and terahertz regions. To increase the absorption of the double-layer array, we first passively modulate the absorption by adjusting the geometric structure and incidenangle, and then actively modulate the potential by adjusting the chemical potential of graphene. Then we find we can enhance absorption by increasing the cross-arm width. In addition, the absorption increases when we increase the incident angle on x-polarization within a certain range. As chemical potential increases, the absorption also can be evidently enhanced. Due to these outstanding characteristics, the double-layer array is beneficial to the design of multi-band absorber.