Generation and control of high-order harmonics by the interaction of an infrared laser with a thin graphite layer

We demonstrate the possibility to control the generation of high-order harmonics by a thin layer of graphite upon varying the polarization and intensity of the laser field. While for monochromatic linearly polarized laser fields all odd-order harmonics are emitted, we find that even for very large deviations from exact circular polarization (the elliptical polarization angle is θ = 45°), the dynamical symmetry based selection rules Ω = (6m ± 1)ω, m = 1, 2, 3…, where ω and Ω are the fundamental and harmonic frequencies [Phys. Rev. Lett 80, 3743, 1998], are valid. Our results show that the generation and control of high-order harmonics in thin layers of graphite by varying the polarization and intensity of an infrared laser field is feasible and should be observed in experiments.