Intersubband Electronic Oscillations an Armchair Graphene Nanoribbon in the Presence of Bichromatic Light Waves

We study analytically an armchair graphene nanoribbon (AGNR) in the presence of a bichromatic light wave, consisting of intense low-frequency and perturbative high frequency modes. The electric fields of both waves are directed parallel to the ribbon axis. The Dirac equation describing the electron-nonstationary field interaction is employed and solved in the resonant approximation. This allows us to calculate in an explicit form the Rabi frequency of the resonant transitions between the hole and electron size-quantized subbands, induced by the weak wave. The dependencies of the Rabi frequency on the parity of the low frequency photon numbers, magnitudes of the electric fields and ribbon width are examined and found to be in line with those obtained by numerical methods. We show that the Rabi frequency associated with the additional weak wave exceeds that generated by only the strong mode.