Nonlinear THz Plasmonics in Bi2Se3 Topological Insulator

We report evidence of the nonlinear response of the Dirac surface plasmon on a patterned film of Bi2Se3 topological insulator. A redshift of the plasmon peak is induced by the strong THz electric field provided by the TeraFERMI beamline at the Free Electron Laser Fermi at Elettra in Trieste (Italy). The nonlinear plasmonic behavior on a topological insulator has been unveiled for the first time.