1209.4833 (Torben Winzer et al.)

Microscopic mechanism for transient population inversion and optical
gain in graphene    [PDF]

Torben Winzer, Ermin Malic, Andreas Knorr

A transient femtosecond population inversion in graphene was recently reported by Li et al., Phys. Rev. Lett. 108, 167401 (2012). Based on a microscopic theory we clarify the underlying microscopic mechanism: Transient gain and population inversion in graphene occurs due to a complex interplay of strong optical pumping and carrier cooling that fills states close to the Dirac point giving rise to a relaxation bottleneck. The subsequent femtosecond decay of the optical gain is mainly driven by Coulomb-induced Auger recombination.

View original: http://arxiv.org/abs/1209.4833