Chirp control of directional current in monolayer graphene by intense few-cycle laser

The residual current density in monolayer graphene driven by an intense few-cycle chirped laser pulse is investigated via numerical solution of the time-dependent Schrodinger equation. It is found that the residual current is sensitive to the initial chirp rate, and the defined asymmetry degree for current along the different polarization direction versus chirp rate follows a simple sinusoidal function. The underlying physical mechanism is the chirp-dependent Landau-Zener-Stuckelberg interference. The chirp control of currents provides a novel convenient tool in the petaHertz switching of two-dimensional materials based optoelectronic devices on the sub-femtosecond timescale.