THz emission from graphene induced by dynamical photon drag

We demonstrate broadband coherent THz emission at room temperature from epitaxial graphene under femtosecond optical excitation induced by photon drag effect. We interpret the emitted THz radiation characteristics with a model describing the electron and hole states beyond the usual massless relativistic scheme. This second-order nonlinear effect relies on the dynamical transfer of light momentum to the carriers by the ponderomotive electric and magnetic forces. Finally, our results indicate that optical rectification in graphene can provide emission up to 60 THz, opening new routes for the generation of ultra-broadband THz pulses at room temperature.