Hangyong Shan, Zhixin Liu, Xingli Wang, Feng Lin, Zheng Liu, Bo Shen, Jun Lou,Xing Zhu, Pulickel M. Ajayan, and Zheyu Fang*
Abstract:Spontaneous emission can be altered by external electromagneticenvironment with the bridge of local density of optical states. Microcavitieshave been widely integrated to accelerate the irreversible spontaneous decay,known as the Purcell effect. However, the Purcell effect breaks down in thestrong coupling regime, where the light-matter interaction is not aperturbation to Fermi’s golden rule. Here, it is found that the emissionintensity of plasmon–exciton polaritons is asymmetrically dependent on thespectral detuning, confirming the collapse of Purcell effect in strongly coupledsystems. Ultrafast nonradiative decays of polaritons play a significant role inrevealing the polariton emission intensity. The nonradiative effect is notaffected by the coherent energy exchange since final states of nonradiativedecays are optically dark and decoupled from Rabi oscillations. Moreover, thenonradiative effect is still valid under intermediate coupling and agrees withthe Purcell effect, which suggests its universality at a variety of couplingregimes. This study opens up a successful approach to investigatespontaneous emission in cavity quantum electrodynamics, which is insightfulto photonic and opto-electronic applications based on exciton-polaritons.
Laser & Photonics Reviews, 2020. 14(12). 
Laser Photonics Reviews - 2020 - Shan.pdf
