  High-harmonic generation (HHG) in solids is an emerging method to probe
ultrafast electron dynamics in solids at attosecond timescale. In this work, we
study HHG from monolayer and bilayer graphene. Bilayer graphenes with AA and AB
stacking are considered in this work. It is found that the monolayer and
bilayer graphenes exhibit significantly different harmonic spectra. The
difference in the spectra is attributed to the interlayer coupling between the
two layers. Also, the intraband and interband contributions to the total
harmonic spectrum play a significant role. Moreover, interesting polarization
and ellipticity dependence are noticed in total harmonic spectrum for monolayer
and bilayer graphene.
