Many-body effects in nonlinear optical responses of 2D layered semiconductors

Grant Aivazian, Hongyi Yu, Sanfeng Wu, Jiaqiang Yan, David G. Mandrus, David Cobden, Wang Yao, Xiaodong Xu

Research output: Contribution to journalArticlepeer-review

34 Scopus citations


We performed ultrafast degenerate pump-probe spectroscopy on monolayer WSe2 near its exciton resonance. The observed differential reflectance signals exhibit signatures of strong manybody interactions including the exciton-exciton interaction and free carrier induced band gap renormalization. The exciton-exciton interaction results in a resonance blue shift which lasts for the exciton lifetime (several ps), while the band gap renormalization manifests as a resonance red shift with several tens ps lifetime. Our model based on the many-body interactions for the nonlinear optical susceptibility fits well the experimental observations. The power dependence of the spectra shows that with the increase of pump power, the exciton population increases linearly and then saturates, while the free carrier density increases superlinearly, implying that exciton Auger recombination could be the origin of these free carriers. Our model demonstrates a simple but efficient method for quantitatively analyzing the spectra, and indicates the important role of Coulomb interactions in nonlinear optical responses of such 2D materials.

Original languageEnglish (US)
Article number025024
Journal2D Materials
Issue number2
StatePublished - Jun 2017
Externally publishedYes

All Science Journal Classification (ASJC) codes

  • General Chemistry
  • General Materials Science
  • Condensed Matter Physics
  • Mechanics of Materials
  • Mechanical Engineering


  • Band gap renormalization
  • Exciton
  • Many body interaction
  • Transition metal dichalcoginides
  • Ultrafast pump-probe spectroscopy


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