▎ 摘　　要

The unique electronic structure of graphene leads to several distinctive optical properties. In this brief review, we outline the current understanding of two general aspects of optical response of graphene: optical absorption and light emission. We show that optical absorption in graphene is dominated by intraband transitions at low photon energies (in the far-infrared spectral range) and by interband transitions at higher energies (from mid-infrared to ultraviolet). We discuss how the intraband and interband transitions in graphene can be modified through electrostatic gating. We describe plasmonic resonances arising from the free-carrier (intraband) response and excitonic effects that are manifested in the interband absorption. Light emission, the reverse process of absorption, is weak in graphene due to the absence of a band gap. We show that photoluminescence from hot electrons can, however, become observable either through femtosecond laser excitation or strong electrostatic gating. (c) 2012 Elsevier Ltd. All rights reserved.