  We study theoretically interaction of a bilayer graphene with a circularly
polarized ultrafast optical pulse of a single oscillation at an oblique
incidence. The normal component of the pulse breaks the inversion symmetry of
the system and opens up a dynamical band-gap, due to which a valley-selective
population of the conduction band becomes sensitive to the angle of incident of
the pulse. We show that the magnitude of the valley polarization can be
controlled by the angle of incidence, the amplitude, and the angle of in-plane
polarization of the chiral optical pulse. Subsequently, a sequence of a
circularly polarized pulse followed by a linearly polarized femtosecond-long
pulse can be used to control the valley polarization created by the preceding
pulse. Generally, the linearly polarized pulse depolarizes the system. The
magnitude of such a depolarization depends on the amplitude, and the in-plane
polarization angle of the linearly polarized pulse. Our protocol provides a
favorable platform for applications in valleytronics.
