Ultrafast linear dichroism-like absorption dynamics in graphene grown by chemical vapor deposition

A transient linear dichroism-like absorption effect is found in the differential transmission dynamics of graphene. Distinctive ultrafast dynamics are observed, respectively, for parallel and perpendicular linearly polarized pump-probe geometries. Pump-polarization dependence of the ultrafast dynamics is observed obviously. It is found that the ultrafast dynamics excited by any oriented linear polarization pump can be fit well with a linear combination of two ultrafast dynamics, respectively, observed in parallel and perpendicular linearly polarized pump-probe geometries, which is a typical character of linear dichroic absorption effect and implies that a transient linear dichroism-like absorption occurs in graphene. However, the mechanism of the transient linear dichroism-like effect cannot be explained yet within the present framework of theory on graphene. Further theoretical explorations from theoretical physicists are expected.