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
State Key Laboratory of Precision Spectroscopy, East China Normal University, Shanghai 200062, China.
Department of Physics, College of Physical Science and Technology, Xiamen University, Xiamen 361005, China.
Nano Lett. 2022 Mar 9;22(5):2023-2029. doi: 10.1021/acs.nanolett.1c04800. Epub 2022 Feb 24.
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.
微丝中的回音壁模式具有近乎等距的能谱特征。在强激子 - 光子耦合 regime 中，该系统代表一个玻色子级联：一个离散能级的阶梯，维持相邻能级之间的受激跃迁。在此，通过使用飞秒角分辨光谱成像技术，基于一维 ZnO 回音壁微腔的玻色子级联中极化激元的超快动力学被清晰地可视化。观察到极化激元凝聚体从高能级分支到低能级分支的清晰阶梯状形成过程，通过速率方程建模能很好地重现这一过程。值得注意的是，通过测量二阶时间关联因子证明了一个显著的超聚束特征，这可作为玻色子级联的确凿证据。此外，还揭示了数百飞秒时间尺度上的非线性极化激元参量散射动力学。我们的理解为室温下极化激元的超快相干控制铺平了道路。
