Department of Physics, Center for Discovery and Innovation, The City College of New York, 85 St. Nicholas Terrace, New York, NY, 10031, USA.
Department of Electrical Engineering and Computer Science, University of Michigan, Ann Arbor, MI, 48109, USA.
Adv Mater. 2022 Apr;34(15):e2109107. doi: 10.1002/adma.202109107. Epub 2022 Mar 6.
Fluorescent proteins (FPs) have recently emerged as a serious contender for realizing ultralow threshold room temperature exciton-polariton condensation and lasing. This contribution investigates the thermalization of FP microcavity exciton-polaritons upon optical pumping under ambient conditions. Polariton cooling is realized using a new FP molecule, called mScarlet, coupled strongly to the optical modes in a Fabry-Pérot cavity. Interestingly, at the threshold excitation energy (fluence) of ≈9 nJ per pulse (15.6 mJ cm ), an effective temperature is observed, T ≈ 350 ± 35 K close to the lattice temperature indicative of strongly thermalized exciton-polaritons at equilibrium. This efficient thermalization results from the interplay of radiative pumping facilitated by the energetics of the lower polariton branch and the cavity Q-factor. Direct evidence for dramatic switching from an equilibrium state into a metastable state is observed for the organic cavity polariton device at room temperature via deviation from the Maxwell-Boltzmann statistics at k = 0 above the threshold. Thermalized polariton gases in organic systems at equilibrium hold substantial promise for designing room temperature polaritonic circuits, switches, and lattices for analog simulation.
荧光蛋白（FPs）最近成为实现超低阈值室温激子极化激元凝聚和激光的有力竞争者。本研究探讨了在环境条件下光泵浦下 FP 微腔激子极化激元的热化过程。通过一种新的 FP 分子 mScarlet 与 Fabry-Pérot 腔中的光学模式强耦合，实现了极化激元冷却。有趣的是，在约 9 nJ 每脉冲（15.6 mJ cm ）的阈值激发能量（通量）下，观察到有效温度 T 约为 350 ± 35 K，接近晶格温度，表明在平衡时激子极化激元已强烈热化。这种有效的热化是由下极化激元支的能量和腔 Q 因子促进的辐射泵浦相互作用所致。在室温下，通过在阈值以上偏离 Maxwell-Boltzmann 统计，直接观察到有机腔极化激元器件从平衡态到亚稳态的显著转变。在平衡态的有机体系中热化的极化激元气体为设计室温极化激子电路、开关和用于模拟的晶格提供了巨大的可能性。
