Charged biexciton polaritons sustaining strong nonlinearity in 2D semiconductor-based nanocavities.

Wei, Ke; Liu, Qirui; Tang, Yuxiang; Ye, Yingqian; Xu, Zhongjie; Jiang, Tian · Nat Commun · 2023

basic_science · Level V

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Abstract

Controlling the interaction between light and matter at micro- and nano-scale can provide new opportunities for modern optics and optoelectronics. An archetypical example is polariton, a half-light-half-matter quasi particle inheriting simultaneously the robust coherence of light and the strong interaction of matter, which plays an important role in many exotic phenomena. Here, we open up a new kind of cooperative coupling between plasmon and different excitonic complexes in WS<sub>2</sub>-silver nanocavities, namely plasmon-exciton-trion-charged biexciton four coupling states. Thanks to the large Bohr radius of up to 5 nm, the charged biexciton polariton exhibits strong saturation nonlinearity, ~30 times higher than the neutral exciton polariton. Transient absorption dynamics further reveal the ultrafast many-body interaction nature, with a timescale of <100 fs. The demonstration of biexciton polariton here combines high nonlinearity, simple processing and strong scalability, permitting access for future energy-efficient optical switching and information processing.