Enhanced terahertz absorption of graphene composite integrated with double circular metal ring array

Graphene-based terahertz (THz) devices, such as modulators, detectors, and absorbers, play important roles in terahertz applications due to graphene’s effectively tunable terahertz absorption. The features of these terahertz devices are greatly related to the THz absorption of graphene. However, the monolayer graphene shows limited absorption to terahertz waves. In this paper, we demonstrated a new graphene composite with a double circular metal ring array deposited on graphene to enhance the absorption. The graphene composite consists of a double circular metal ring array, a monolayer graphene, silicon dioxide, and silicon substrates. The double circular metal ring array locally enhances the electromagnetic field on graphene and further increases graphene’s absorption. It shows that the peak absorption of the proposed graphene composite is increased to 95% for graphene Fermi level 0 eV at room temperature, which is more than seven times larger than that of the graphene composite without the double circular metal ring array. The enhanced terahertz absorption of the proposed graphene composite shows the potential ability of improving modulation depth and insertion loss of a THz reflection modulator.