Graphene acoustic plasmon resonator for ultrasensitive infrared spectroscopy
Graphene acoustic plasmon resonator for ultrasensitive infrared spectroscopy
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DOI：
10.1038/s41565-019-0363-8
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发表时间：
2019-04-01
影响因子：
38.3
通讯作者：
Oh, Sang-Hyun
中科院分区：
文献类型：
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作者：
Lee, In-Ho;Yoo, Daehan;Oh, Sang-Hyun
等离子体激元学中的基本障碍之一是电磁场限制和与自由空间光的耦合效率之间的权衡，这是激发源和等离子体激元模式之间的大动量失配的结果。特别地，石墨烯中的声等离子体具有极端水平的场约束，以及极端的动量失配。在这里，我们证明了这种基本的妥协可以克服，并证明了石墨烯声等离子体共振器具有近乎完美的吸收（94%）入射中红外光。这种高效率是通过利用两级耦合方案实现的：自由空间光耦合到传统的石墨烯等离子体，然后耦合到超限制的声学等离子体。为了实现这一方案，我们将未图案化的大面积石墨烯转移到模板剥离的超平金属带上。单片集成的光学间隔器和反射器进一步提高了增强效果。我们表明，石墨烯声等离子体允许超灵敏的测量吸收带和表面声子模式在埃厚的蛋白质和SiO（2）层，分别。我们的声学等离子体共振器平台是可扩展的，可以利用光物质相互作用的潜在应用，包括光谱学，传感，超表面和光电子学的最终水平。
One of the fundamental hurdles in plasmonics is the trade-off between electromagnetic field confinement and the coupling efficiency with free-space light, a consequence of the large momentum mismatch between the excitation source and plasmonic modes. Acoustic plasmons in graphene, in particular, have an extreme level of field confinement, as well as an extreme momentum mismatch. Here, we show that this fundamental compromise can be overcome and demonstrate a graphene acoustic plasmon resonator with nearly perfect absorption (94%) of incident mid-infrared light. This high efficiency is achieved by utilizing a two-stage coupling scheme: free-space light coupled to conventional graphene plasmons, which then couple to ultraconfined acoustic plasmons. To realize this scheme, we transfer unpatterned large-area graphene onto template-stripped ultraflat metal ribbons. A monolithically integrated optical spacer and a reflector further boost the enhancement. We show that graphene acoustic plasmons allow ultrasensitive measurements of absorption bands and surface phonon modes in angstrom-thick protein and SiO(2 )layers, respectively. Our acoustic plasmon resonator platform is scalable and can harness the ultimate level of light-matter interactions for potential applications including spectroscopy, sensing, metasurfaces and optoelectronics.