Terahertz Conductivity of Photoexcited Multi-Layer Graphene

In this work we study infrared optical pump induced changes in terahertz conductivity of 80-layered graphene on dielectric and semiconductor substrates using terahertz time-domain spectroscopy. Results indicate that the conductivity of investigated material strongly depends on pumping intensity and the type of underlying substrate. The findings are helpful for designing of optically tunable terahertz devices based on new two-dimensional material beyond graphene monolayer.