Zeng Zheng, Mendis Madu N, Waldeck David H, Wei Jianjun
Department of Nanoscience, Joint School of Nanoscience and Nanoengineering, University of North Carolina at Greensboro, Greensboro, NC 27401, USA.
Department of Chemistry, University of Pittsburgh, Pittsburgh, PA 15260, USA.
RSC Adv. 2016;6(21):17196-17203. doi: 10.1039/C6RA01105E. Epub 2016 Feb 3.
Surface plasmon resonance (SPR) of nanostructured thin metal films (so-called nanoplasmonics) has attracted intense attention due to its versatility for optical sensing and chip-based device integration. Understanding the underlying physics and developing applications of nanoplasmonic devices with desirable optical properties, e.g. intensity of light scattering and high refractive index (RI) sensitivity at the perforated metal film, is crucial for practical uses in physics, biomedical detection, and environmental monitoring. This work presents a semi-analytical model that enables decomposition and quantitative analysis of surface plasmon generation at a new complex nanoledge aperture structure under plane-wave illumination, thus providing insight on how to optimize plasmonic devices for optimal plasmonic generation efficiencies and RI sensitivity. A factor analysis of parameters (geometric, dielectric-RI, and incident wavelength) relevant to surface plasmon generation is quantitatively investigated to predict the surface plasmon polariton (SPP) generation efficiency. In concert with the analytical treatment, a finite-difference time-domain (FDTD) simulation is used to model the optical transmission spectra and RI sensitivity as a function of the nanoledge device's geometric parameters, and it shows good agreement with the analytical model. Further validation of the analytical approach is provided by fabricating subwavelength nanoledge devices and testing their optical transmission and RI sensitivity.
纳米结构薄金属膜的表面等离子体共振（SPR，即所谓的纳米等离子体学）因其在光学传感和基于芯片的器件集成方面的多功能性而备受关注。理解其背后的物理原理并开发具有理想光学特性（如穿孔金属膜处的光散射强度和高折射率（RI）灵敏度）的纳米等离子体器件的应用，对于在物理、生物医学检测和环境监测中的实际应用至关重要。这项工作提出了一个半解析模型，该模型能够在平面波照明下对新型复杂纳米边缘孔径结构处的表面等离子体产生进行分解和定量分析，从而深入了解如何优化等离子体器件以实现最佳的等离子体产生效率和RI灵敏度。对与表面等离子体产生相关的参数（几何参数、介电常数 - RI和入射波长）进行因子分析，以定量预测表面等离子体激元（SPP）的产生效率。与解析处理相结合，使用时域有限差分（FDTD）模拟来模拟作为纳米边缘器件几何参数函数的光传输光谱和RI灵敏度，并且它与解析模型显示出良好的一致性。通过制造亚波长纳米边缘器件并测试其光传输和RI灵敏度，为该解析方法提供了进一步的验证。
