Department of Physical Electronics, Fleischman Faculty of Engineering, ‡School of Chemistry, Raymond and Beverly Sackler Faculty of Exact Sciences, and §Center for Light-Matter Interaction, Tel Aviv University , Tel Aviv 69978, Israel.
Nano Lett. 2017 Dec 13;17(12):7675-7683. doi: 10.1021/acs.nanolett.7b03751. Epub 2017 Nov 2.
We use femtosecond transient absorption spectroscopy to study the temporal dynamics of strongly coupled exciton-plasmon polaritons in metasurfaces of aluminum nanoantennas coated with J-aggregate molecules. Compared with the thermal nonlinearities of aluminum nanoantennas, the exciton-plasmon hybridization introduces strong ultrafast nonlinearities in the composite metasurfaces. Within femtoseconds after the pump excitation, the plasmonic resonance is broadened and shifted, showcasing its high sensitivity to excited-state modification of the molecular surroundings. In addition, we observe temporal oscillations due to the deep subangstrom acoustic breathing modes of the nanoantennas in both bare and hybrid metasurfaces. Finally, unlike the dynamics of hybrid states in optical microcavities, here, ground-state bleaching is observed with a significantly longer relaxation time at the upper polariton band.
我们使用飞秒瞬态吸收光谱研究了涂有 J- 聚集体分子的铝纳米天线金属超表面中强耦合激子-等离子体极化激元的时间动力学。与铝纳米天线的热非线性相比，激子-等离子体杂化在复合金属超表面中引入了强超快非线性。在泵浦激发后的飞秒内，等离子体共振被展宽和移动，显示出其对分子环境激发态修饰的高灵敏度。此外，我们观察到由于纳米天线的深亚埃声波呼吸模式而产生的时间振荡，无论是在裸金属超表面还是混合金属超表面中都有观察到。最后，与光学微腔中混合态的动力学不同，在这里，在高阶极化激元带中观察到基态漂白，其弛豫时间明显更长。
