Department of Materials Science and Engineering, National Taiwan University, No. 1, Sec. 4, Roosevelt Rd., Taipei 10617, Taiwan.
Nanoscale. 2017 Nov 9;9(43):16950-16959. doi: 10.1039/c7nr05988d.
The optical hybridization of localized surface plasmons and photonic modes of dielectric nanostructures provides us wide arenas of opportunities for designing tunable nanophotonics with excellent spectral selectivity, signal enhancement, and light harvesting for many optical applications. Graphene-supported Au nanoprisms on a periodic Si nanopillar array will be an ideal model system for examining such an optical hybridization effect between plasmonic modes and photonic modes. Here, through the measurement of the reflectance spectra as well as graphene phonons by surface-enhanced Raman scattering (SERS), we investigated both the far-field and near-field properties of these optically hybridized modes. The effects of photonic modes and Mie resonances of the Si nanopillars on the localized surface plasmons of the Au nanoprisms and on their near-field enhancement were experimentally elucidated through the measurements of graphene phonons using two excitation lasers with wavelengths of 532 and 785 nm. The wavelength-dependent SERS intensities of monolayer graphene are clearly understood in terms of the optical hybridization, and the SERS enhancement factor estimated from finite-difference time-domain simulations exhibited good agreement with the measurements. The elucidated spectral tunability in the near-field light-matter interaction would be useful for potential applications in various types of graphene-based photonics.
局域表面等离激元与介电纳米结构的光子模式的光学杂化为设计具有出色光谱选择性、信号增强和光收集的可调谐纳米光子学提供了广阔的机会，适用于许多光学应用。在周期性硅纳米柱阵列上的石墨烯负载的金纳米棱柱将是研究等离子体模式和光子模式之间这种光学杂化效应的理想模型系统。在这里，我们通过测量反射率谱以及表面增强拉曼散射 (SERS) 的石墨烯声子，研究了这些光杂化模式的远场和近场性质。通过使用波长为 532nm 和 785nm 的两个激发激光测量石墨烯声子，实验阐明了光子模式和硅纳米柱的 Mie 共振对金纳米棱柱的局域表面等离激元和近场增强的影响。根据光学杂化，清楚地理解了单层石墨烯的依赖于波长的 SERS 强度，并且从有限差分时域模拟估计的 SERS 增强因子与测量结果吻合良好。阐明的近场光物质相互作用中的光谱可调谐性将有助于各种类型的基于石墨烯的光子学的潜在应用。
