Harmonic generation in carbon nanotubes: quantum-mechanical approach

The nonlinear optical response of a single-wall carbon nanotube (CNT) due to the interaction with femtosecond laser pulses is investigated. The analysis utilizes the quantum kinetic equations for pi-electrons with both intra-band and inter-band transitions accounted. In the regime of weak driving fields the kinetic equations have been solved by the perturbation method and the third-order nonlinear susceptibility of different achiral CNTs has been calculated. In the strong driving field regime, a non-perturbative approach using the numerical solution of the quantum kinetic equations in the time domain has been developed and the density of the axial electric current in CNT has been calculated. The amplitude of this current and the conversion efficiency in dependence on the number of the high-order harmonics, the CNT type, the frequency and the intensity of the driving field have been predicted.