• 文献标题:   Gate-tunable third-order nonlinear optical response of massless Dirac fermions in graphene
  • 文献类型:   Article
  • 作  者:   JIANG T, HUANG D, CHENG JL, FAN XD, ZHANG ZH, SHAN YW, YI YF, DAI YY, SHI L, LIU KH, ZENG CG, ZI J, SIPE JE, SHEN YR, LIU WT, WU SW
  • 作者关键词:  
  • 出版物名称:   NATURE PHOTONICS
  • ISSN:   1749-4885 EI 1749-4893
  • 通讯作者地址:   Fudan Univ
  • 被引频次:   39
  • DOI:   10.1038/s41566-018-0175-7
  • 出版年:   2018

▎ 摘  要

Graphene with massless Dirac fermions can have exceptionally strong third-order optical nonlinearities. Yet reported values of nonlinear optical susceptibilities for third-harmonic generation (THG), four-wave mixing (FWM) and self-phase modulation vary over six orders of magnitude. Such variation likely arises from frequency-dependent resonance effects of different processes in graphene under different doping. Here, we report an experimental study of THG and FWM in graphene using gate tuning to adjust the doping level and vary the resonant condition. We find that THG and sum-frequency FWM are strongly enhanced in heavily doped graphene, while the difference-frequency FWM appears just the opposite. Difference-frequency FWM exhibited a novel divergence towards the degenerate case in undoped graphene, leading to a giant enhancement of the nonlinearity. The results are well supported by theory. Our full understanding of the diverse nonlinearity of graphene paves the way towards future design of graphene-based nonlinear optoelectronic devices.