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

Abstract

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 $\ensuremath{\theta}=45\ifmmode^\circ\else\textdegree\fi{}),$ the dynamical symmetry based selection rules $\ensuremath{\Omega}=(6m\ifmmode\pm\else\textpm\fi{}1)\ensuremath{\omega},$ $m=1,2,3\dots{},$ where $\ensuremath{\omega}$ and $\ensuremath{\Omega}$ 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.