DC current induced second order optical nonlinearity in graphene

We calculate the dc current induced second harmonic generation in doped graphene using the semiconductor Bloch equations under relaxation time approximations. We find that the maximum value of the effective second order susceptibility appears when the fundamental photon energy matches the chemical potential. For a surface current density 1.1 x 10(3) A/m and a relaxation time at optical frequencies of 13 fs, the effective second order susceptibility chi((2);xxx)(eff) can be as large as 10(-7)m/V for h omega = 0.2 eV or 10(-8) m/V for h omega = 0.53 eV. (C) 2014 Optical Society of America