Valley-selective photon-dressed states in transition metal dichalcogenides

Trevor Lamountain, Yen Jung Chen, Teodor K. Stanev, Nathaniel P. Stern*

*Corresponding author for this work

Research output: Chapter in Book/Report/Conference proceedingConference contribution


When electronic excitations in a semiconductor interact with light, the relevant quasiparticles are hybrid lightmatter dressed states, or exciton-polaritons. In monolayer transition metal dichalcogenides, a class of 2D direct bandgap semiconductors, optical excitations selectively populate distinct momentum valleys with correlated spin projection. The combination of this spin-valley locking with photon dressed states can lead to new optical phenomena in these materials. We present spectroscopic measurements of valley-specific exciton-polaritons in monolayer 2D materials in distinct regimes. When a monolayer is embedded in a dielectric microcavity, strong coupling exciton-polaritons are achieved. Cavity-modified dynamics of the dressed states are inferred from emission. Polarization persists up to room temperature in monolayer MoS2, in contrast with bare material. We also show that distinct regimes of valley-polarized exciton-polaritons can be accessed with microcavity engineering by tuning system parameters such as cavity decay rate and exciton-photon coupling strength. Further, we report results showing that polarization-sensitive ultrafast spectroscopy can enable sensitive measurements of the valley optical Stark shift, a light-induced dressed state energy shift, in monolayer semiconductors such as WSe2 and MoS2. These findings demonstrate distinct approaches to manipulating the picosecond dynamics of valleysensitive dressed states in monolayer semiconductors.

Original languageEnglish (US)
Title of host publicationUltrafast Phenomena and Nanophotonics XXII
EditorsAbdulhakem Y. Elezzabi, Markus Betz
ISBN (Electronic)9781510615458
StatePublished - 2018
EventUltrafast Phenomena and Nanophotonics XXII 2018 - San Francisco, United States
Duration: Jan 29 2018Jan 31 2018

Publication series

NameProceedings of SPIE - The International Society for Optical Engineering
ISSN (Print)0277-786X
ISSN (Electronic)1996-756X


OtherUltrafast Phenomena and Nanophotonics XXII 2018
Country/TerritoryUnited States
CitySan Francisco


  • 2D materials
  • Kerr rotation
  • Stark effect
  • dressed states
  • exciton-polaritons
  • valley pseudospin

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics
  • Computer Science Applications
  • Applied Mathematics
  • Electrical and Electronic Engineering


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