Separation of valley excitons in a MoS 2 monolayer using a subwavelength asymmetric groove array

Liuyang Sun, Chun Yuan Wang, Alex Krasnok, Junho Choi, Jinwei Shi, Juan Sebastian Gomez Diaz, André Zepeda, Shangjr Gwo, Chih Kang Shih, Andrea Alù, Xiaoqin Li

Research output: Contribution to journalArticlepeer-review

92 Scopus citations


Excitons in monolayer transition metal dichalcogenides are formed at K and K′ points at the boundary of the Brillouin zone. They acquire a valley degree of freedom, which has been explored as an alternative information carrier, analogous to charge or spin. Two opposite valleys in transition metal dichalcogenides can be optically addressed using light with different helicity. Here, we demonstrate that valley-polarized excitons can be sorted and spatially separated at room temperature by coupling a MoS 2 monolayer to a subwavelength asymmetric groove array. In addition to separation of valley excitons in real space, emission from valley excitons is also separated in photon momentum-space; that is, the helicity of photons determines a preferential emission direction. Our work demonstrates that metasurfaces can facilitate valley transport and establish an interface between valleytronic and photonic devices, thus addressing outstanding challenges in the field of valleytronics.

Original languageEnglish (US)
Pages (from-to)180-184
Number of pages5
JournalNature Photonics
Issue number3
StatePublished - Mar 1 2019

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Atomic and Molecular Physics, and Optics


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