Femtosecond Dynamics of a Polariton Bosonic Cascade at Room Temperature

作者：Chen, Fei; Zhou, Hang; Li, Hui^*; Cao, Junhui; Luo, Song; Sun, Zheng; Zhang, Zhe; Shao, Ziqiu; Sun, Fenghao; Zhou, Beier; Dong, Hongxing; Xu, Huailiang; Xu, Hongxing; Kavokin, Alexey; Chen, Zhanghai^*; Wu, Jian^*

来源：Nano Letters, 2022, 22(5): 2023-2029.

DOI：10.1021/acs.nanolett.1c04800

• exciton polariton
• bosonic cascade
• ultrafast dynamics
• angle-resolved photoluminescence spectroscopy
• second-order time correlation factor

Whispering gallery modes in a microwire are characterized by a nearly equidistant energy spectrum. In the strong exciton-photon coupling regime, this system represents a bosonic cascade: a ladder of discrete energy levels that sustains stimulated transitions between neighboring steps. Here, by using a femtosecond angle-resolved spectroscopic imaging technique, the ultrafast dynamics of polaritons in a bosonic cascade based on a one-dimensional ZnO whispering gallery microcavity are explicitly visualized. Clear ladder-form build-up processes from higher to lower energy branches of the polariton condensates are observed, which are well reproduced by modeling using rate equations. Remarkably, a pronounced superbunching feature, which could serve as solid evidence for bosonic cascades, is demonstrated by the measured second-order time correlation factor. In addition, the nonlinear polariton parametric scattering dynamics on a time scale of hundreds of femtoseconds are revealed. Our understandings pave the way toward ultrafast coherent control of polaritons at room temperature.

• 单位
  厦门大学; 中国科学院