21 research outputs found
Graphene valley polarization as a function of carrier-envelope phase in few-cycle laser pulses and its footprints in harmonic signals
We consider coherent dynamics of graphene charged carriers exposed to an
intense few-cycle linearly polarized laser pulse. The results, obtained by
solving the generalized semiconductor Bloch equations numerically in the
Hartree-Fock approximation, taking into account many-body Coulomb interaction,
demonstrate strong dependence of the valley polarization on the
carrier-envelope phase (CEP), which is interpolated by the simple sinusoidal
law. Then we consider harmonic generation in multi-cycle laser field by
graphene preliminary exposed to an intense few-cycle laser pulse. We show that
the second harmonic's intensity is a robust observable quantity that provides a
gauge of CEP for pulse durations up to two optical cycles, corresponding to 40
at the wavelength of 6.2 .Comment: 9 pages, 10 figure
Long-range correlation-induced effects at high-order harmonic generation on graphene quantum dots
This paper focuses on investigating high-order harmonic generation (HHG) in
graphene quantum dots (GQDs) under intense near-infrared laser fields. To model
the GQD and its interaction with the laser field, we utilize a mean-field
approach. Our analysis of the HHG power spectrum reveals fine structures and a
noticeable enhancement in cutoff harmonics due to the long-range correlations.
We also demonstrate the essential role of Coulomb interaction in determining of
harmonics intensities and cutoff position. Unlike atomic HHG, where the cutoff
energy is proportional to the pump wave intensity, in GQDs the cutoff energy
scales with the square root of the field strength amplitude. A detailed
time-frequency analysis of the entire range of HHG spectrum is presented using
a wavelet transform. The analysis reveals intricate details of the spectral and
temporal fine structures of HHG, offering insights into the various HHG
mechanisms in GQDs.Comment: 10 pages, 15 figure