Photocarrier-Induced Active Control of Second-Order Optical Nonlinearity in Monolayer MoS2. Academic Article uri icon


  • Atomically thin transition metal dichalcogenides (TMDs) in their excited states can serve as exceptionally small building blocks for active optical platforms. In this scheme, optical excitation provides a practical approach to control light-TMD interactions via the photocarrier generation, in an ultrafast manner. Here, it is demonstrated that via a controlled generation of photocarriers the second-harmonic generation (SHG) from a monolayer MoS2 crystal can be substantially modulated up to 55% within a timeframe of 250 fs, a set of performance characteristics that showcases the promise of low-dimensional materials for all-optical nonlinear data processing. The combined experimental and theoretical study suggests that the large SHG modulation stems from the correlation between the second-order dielectric susceptibility (2) and the density of photoexcited carriers in MoS2 . Indeed, the depopulation of the conduction band electrons, at the vicinity of the high-symmetry K/K' points of MoS2 , suppresses the contribution of interband electronic transitions in the effective (2) of the monolayer crystal, enabling the all-optical modulation of the SHG signal. The strong dependence of the second-order optical response on the density of photocarriers reveals the promise of time-resolved nonlinear characterization as an alternative route to monitoring carrier dynamics in excited states of TMDs.

published proceedings

  • Small

author list (cited authors)

  • Taghinejad, M., Xu, Z., Wang, H., Taghinejad, H., Lee, K., Rodrigues, S. P., ... Cai, W.

citation count

  • 22

complete list of authors

  • Taghinejad, Mohammad||Xu, Zihao||Wang, Hua||Taghinejad, Hossein||Lee, Kyu-Tae||Rodrigues, Sean P||Adibi, Ali||Qian, Xiaofeng||Lian, Tianquan||Cai, Wenshan

publication date

  • February 2020


published in