Tunable terahertz cloaking and lasing by the optically pumped graphene wrapped on a dielectric cylinder

The scattering properties of a dielectric cylinder wrapped by a monolayer of graphene under an external optical pump are investigated. The THz cloaking is realized due to the strong suppression of scattering at certain range of frequencies. While at some other frequencies, the scattering can be dramatically enhanced, and a THz lasing can be achieved due to the enormous amplification of the local field by the graphene plasmon. Both the work frequencies of THz lasing and cloaking can be tuned continuously by the quasi-Fermi energy of graphene. Our proposal can pave the way to all-optical manipulation of THz lasing and cloaking based on the optically pumped graphene. (paper)