▎ 摘　　要

We compute the terahertz third-order nonlinear conductance of metallic armchair graphene nanoribbons using time-dependent perturbation theory. Significant enhancement of the intrinsic third-order conductance over the result for instrinsic 2D single-layer graphene is observed over a wide range of temperatures. We also investigate the nonlinear response of extrinsic metallic acGNR with vertical bar E-F vertical bar << 200 meV. We find that the third-order conductance exhibits a strong Fermi level dependence at low temperatures. A third-order critical field strength of between similar to 1 and 5 kV/m is computed for the Kerr conductance as a function of temperature. For the third-harmonic conductance, the minimum critical field is computed to be similar to 5 kV/m.