Lee Kuang-Li, Chang Chia-Chun, You Meng-Lin, Pan Ming-Yang, Wei Pei-Kuen
Research Center for Applied Sciences, Academia Sinica, 128, section 2, Academia Road, Nangkang, Taipei, 11529, Taiwan.
Department of Optoelectronics, National Taiwan Ocean University, Keelung, 20224, Taiwan.
Sci Rep. 2018 Jun 27;8(1):9762. doi: 10.1038/s41598-018-28122-5.
Improving surface sensitivities of nanostructure-based plasmonic sensors is an important issue to be addressed. Among the SPR measurements, the wavelength interrogation is commonly utilized. We proposed using blue-shifted surface plasmon mode and Fano resonance, caused by the coupling of a cavity mode (angle-independent) and the surface plasmon mode (angle-dependent) in a long-periodicity silver nanoslit array, to increase surface (wavelength) sensitivities of metallic nanostructures. It results in an improvement by at least a factor of 4 in the spectral shift as compared to sensors operated under normal incidence. The improved surface sensitivity was attributed to a high refractive index sensitivity and the decrease of plasmonic evanescent field caused by two effects, the Fano coupling and the blue-shifted resonance. These concepts can enhance the sensing capability and be applicable to various metallic nanostructures with periodicities.
提高基于纳米结构的等离子体传感器的表面灵敏度是一个需要解决的重要问题。在表面等离子体共振（SPR）测量中，通常采用波长询问法。我们提出利用长周期银纳米狭缝阵列中腔模（与角度无关）和表面等离子体模（与角度有关）耦合所引起的蓝移表面等离子体模式和法诺共振，来提高金属纳米结构的表面（波长）灵敏度。与正常入射下工作的传感器相比，这使得光谱位移至少提高了4倍。表面灵敏度的提高归因于高折射率灵敏度以及法诺耦合和蓝移共振这两种效应导致的等离子体倏逝场的减小。这些概念可以增强传感能力，并适用于具有周期性的各种金属纳米结构。
