  We identify and describe how intense short light pulses couple to massless
Dirac fermions in two-dimensional systems. The ensuing excitation dynamics
exhibits unusual scaling with the wavelength of the light due the linear
dispersion of the band structure and the fact that light coupling is efficient
only close to the Dirac points. We exploit these features to achieve valley
polarization of more than 70 % with simple pulse shapes. Quantitative results
are given for pristine graphene.
