Abstract

Femtosecond optical excitation in graphene results in generation of a nonequilibrium carrier distribution [1]. The polarization state of the light pulses used for excitation also plays a crucial role [2-3]. When charge carriers are excited with linearly polarized light, the resulting occupation in momentum space is not isotropic due to the pseudospin selection rules [3]. As illustrated in the inset of Fig. 1(a), the photoexcited electronic distribution is centered along the polarization direction of the exciting pulse. To study this anisotropy we compare the transient absorption signal arising for probe pulses with polarizations parallel and perpendicular to the pump pulse.

© 2015 IEEE