  Polarization characteristic of ultrafast carrier dynamics in multi-layer
CVD-grown graphene is probed with tilted beams (with respected to the graphene
plane). The graphene ultrafast carrier dynamics measurement greatly depends on
both polarization (i.e., orientation of linear polarization) and wave vector of
probe beam. The differential reflectivity \Delta R=R signal of picosecond
dynamics could be continuously altered from positive to negative by changing
the probe polarization from P to S when the dynamics is probed by a total
internal reflected beam. The polarization dependent \Delta R=R signal around 0
delay time is positive. It could be altered to negative by changing the probe
polarization if the probe beam is non-total internal reflected beam. However,
no sign reversal was observed for differential transmittance \Delta T=T . These
extremely unexpected results indicate the anisotropy of graphene carrier
dynamics. Thus the ultrafast carrier dynamics should be further studied with
consideration of the anisotropic structure (in- and out-of-graphene plane) of
graphene.
