Photo-induced enhanced negative absorption in the graphene-dielectric hybrid meta-structure

Recently, the negative absorption in graphene-based metamaterials became a very attractive direction of THz electronic devices. Here we propose a graphene-dielectric hybrid meta-structure to realize photo-induced enhanced negative absorption in the THz regime, which results from strong graphene-light interaction. The negative absorption is derived from the degradation of the conductivity of graphene under optical pump. Meanwhile, the graphene-dielectric hybrid meta-structure introduces dispersion relation and resonance mode, which can couple with the incident wave to construct a strong resonance. In this case, both the dispersion of the propagating waves and resonance are contributed to the graphene-light interaction and enhance the negative absorption, in which the resonance coupling determines the distribution of negative absorption, and the maximum is dominated by dispersion. More importantly, compared with the previous work, the negative absorption is increased by nearly 100 times by adopting this meta-structure.