Giant All-Optical Modulation of Second-Harmonic Generation Mediated by Dark Excitons

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A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä
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ACS Photonics
All-optical control of nonlinear photonic processes in nanomaterials is of significant interest from a fundamental viewpoint and with regard to applications ranging from ultrafast data processing to spectroscopy and quantum technology. However, these applications rely on a high degree of control over the nonlinear response, which still remains elusive. Here, we demonstrate giant and broadband all-optical ultrafast modulation of second-harmonic generation (SHG) in monolayer transition-metal dichalcogenides mediated by the modified excitonic oscillation strength produced upon optical pumping. We reveal a dominant role of dark excitons to enhance SHG by up to a factor of ∼386 at room temperature, 2 orders of magnitude larger than the current state-of-the-art all-optical modulation results. The amplitude and sign of the observed SHG modulation can be adjusted over a broad spectral range spanning a few electronvolts with ultrafast response down to the sub-picosecond scale via different carrier dynamics. Our results not only introduce an efficient method to study intriguing exciton dynamics, but also reveal a new mechanism involving dark excitons to regulate all-optical nonlinear photonics.
| openaire: EC/H2020/820423/EU//S2QUIP | openaire: EC/H2020/834742/EU//ATOP | openaire: EC/H2020/965124/EU//FEMTOCHIP
Bright Excitons, Dark Excitons, Optically-Modulated Excitonic Strength, Second-Harmonic Generation, Transition Metal Dichalcogenides Monolayers, Ultrafast Optical Modulation
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Wang, Y, Das, S, Iyikanat, F, Dai, Y, Li, S, Guo, X, Yang, X, Cheng, J, Hu, X, Ghotbi, M, Ye, F, Lipsanen, H, Wu, S, Hasan, T, Gan, X, Liu, K, Sun, D, Dai, Q, García De Abajo, F J, Zhao, J & Sun, Z 2021, ' Giant All-Optical Modulation of Second-Harmonic Generation Mediated by Dark Excitons ', ACS Photonics, vol. 8, no. 8, pp. 2320-2328 .