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

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 WS2-silver nanocavities, namely plasmon-excitontrion-charged biexciton four coupling states. Thanks to the large Bohr radius of up to 5 nm, the charged biexciton polariton exhibits strong saturation nonlinearity, similar to 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.

Automated summary

Controlling light-matter interaction at micro- and nano-scale is important for modern optics and optoelectronics. The study explores a new cooperative coupling between plasmon and different excitonic complexes in WS2-silver nanocavities, resulting in the creation of plasmon-excitontrion-charged biexciton four coupling states. The demonstration of the charged biexciton polariton showcases high nonlinearity and potential for energy-efficient optical switching and information processing.