Ultrafast modulation in a THz graphene-based flat absorber through negative photoconductivity

We present the experimental and theoretical study of an ultrafast graphene based thin film absorption modulator for operation in the THz regime. The flat modulator is composed of a graphene sheet placed on a dielectric layer backed by a metallic back reflector. A near IR pulse induces the generation of hot carriers in the graphene sheet reducing effectively its conductivity. The system provides a platform with ultrafast modulation capability for flat optics and graphene based metasurfaces applications.