Dayal Govind, Morichika Ikki, Ashihara Satoshi
Institute of Industrial Science, The University of Tokyo, 4-6-1, Komaba, Meguro-Ku, Tokyo 153-8505, Japan.
J Phys Chem Lett. 2021 Apr 1;12(12):3171-3175. doi: 10.1021/acs.jpclett.1c00081. Epub 2021 Mar 23.
Vibrational strong coupling (VSC) between a vacuum field and molecules in a cavity offers promising applications in cavity-modified chemical reactions and ultrasensitive vibrational spectroscopy. At present, in order to realize VSC, bulky microcavities with large mode volume are utilized, which limits their potential applications at the nanoscale. Here, we report on the experimental realization of strong coupling between molecular vibrations and infrared photons confined within a deeply subwavelength nanogap patch antenna cavity. Our system exhibits a characteristic anticrossing dispersion, indicating a Rabi splitting of 108 cm at the single resonator level with excellent angular insensitivity. The numerical simulations and theoretical analyses quantitatively reveal that the strength of coupling depends on the cavity field-molecule overlap integral and the image charge effect. VSC at the single nanogap patch antenna level paves the way for molecular-scale chemistry, ultrasensitive biosensors, and the development of ultralow-power all-optical devices in the mid-infrared spectral range.
真空场与腔内分子之间的振动强耦合（VSC）在腔修饰化学反应和超灵敏振动光谱学方面具有广阔的应用前景。目前，为了实现VSC，人们使用了具有大模式体积的大型微腔，这限制了它们在纳米尺度上的潜在应用。在此，我们报告了分子振动与限制在深亚波长纳米间隙贴片天线腔内的红外光子之间强耦合的实验实现。我们的系统表现出特征性的反交叉色散，表明在单谐振器水平上拉比分裂为108 cm，具有出色的角度不敏感性。数值模拟和理论分析定量地揭示了耦合强度取决于腔场 - 分子重叠积分和镜像电荷效应。单纳米间隙贴片天线水平的VSC为分子尺度化学、超灵敏生物传感器以及中红外光谱范围内超低功耗全光器件的发展铺平了道路。
