jp5b03819_si_001.pdf (2.74 MB)
Two-Photon Absorption in Graphene Enhanced by the Excitonic Fano Resonance
journal contribution
posted on 2015-07-23, 00:00 authored by Weiqiang Chen, Yu Wang, Wei JiWe
report our observation of two-photon absorption (2PA) in graphene
enhanced by the excitonic Fano resonance at the saddle point with
femtosecond laser pulses in the spectral range from 1.8 to 2.9 eV
(or, from 435 to 700 nm). On the basis of the second-order, time-dependent
perturbation theory on interband transitions among three states near
the saddle point of two-dimensional systems (used in the Bassani–Hassan
theoretical model), we develop a semiempirical model to take excitons
in graphene into consideration. We find that the model is in agreement
with the photon-energy dependence of the observed 2PA spectrum with
a scaling factor of B = (1–5) × 102 cm/MW/eV5.