Dipolar Resonance Enhancement and Magnetic Resonance in Cross-Coupled Bow-Tie Nanoantenna Array by Plasmonic Cavity
Dipolar Resonance Enhancement and Magnetic Resonance in Cross-Coupled Bow-Tie Nanoantenna Array by Plasmonic Cavity
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DOI：
10.1021/acsphotonics.5b00088
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发表时间：
2015-07-01
期刊：
影响因子：
7
通讯作者：
Lee, Chengkuo
中科院分区：
文献类型：
--
作者：
Hasan, Dihan;Ho, Chong Pei;Lee, Chengkuo
我们通过插入等离子体腔，通过实验证明了一种在交叉耦合领结纳米天线中进行表面电流工程的简单方法，该方法同时提供（i）改进的类 Fano 偶极共振对比度，（ii）电感应磁共振，以及（iii）增强的灵敏度。通过引入小的几何扰动，我们提出了两个物理参数，偏移（f）和分裂间隙（s），用于共振位置和强度的强调制。我们报道了与传统设计相比至少 3.75 倍的偶极共振，并展示了激发磁等离子体共振的独特机制。最后，我们通过薄 PMMA 涂层 (110 nm) 分别获得了每折射率单位 (RIU) 777.5 和 904 nm 的大波长偏移，用于偶极共振和磁共振。数值研究表明，所提出的具有自相似等离子体腔（SSP BNA）的领结纳米天线阵列结构具有通过重新建立传导电流并提供“开”和“关”状态来灵敏记录 DNA 等分子结合事件的潜力。高密度等离子体天线阵列结构将在光磁、磁等离子体、光捕获和分子指纹的大规模并行超灵敏差分检测等工程应用中具有广阔的前景。
We experimentally demonstrate a simple approach for surface current engineering in a cross-coupled bow-tie nanoantenna by inserting a plasmonic cavity that simultaneously offers (i) improved Fano-like dipolar resonance contrast, (ii) electrically induced magnetic resonance, and (iii) enhanced sensitivity. By introducing a small geometric perturbation, we propose two physical parameters, offset (f) and split gap (s), for strong modulation of resonance location and intensity. We report at least 3.75-fold better dipolar resonance compared with the conventional design and demonstrate a unique mechanism for exciting magnetic plasmonic resonance. Finally, we obtain a large wavelength shift of 777.5 and 904 nm per refractive index unit (RIU) with a thin PMMA coating (110 nm) for the dipolar resonance and magnetic resonance, respectively. Numerical study indicates the potential of the proposed bow-tie nanoantenna array structure with a self-similar plasmonic cavity (SSP BNA) for sensitive recording of binding events of molecules such as DNA by reestablishing conduction current and providing "on" and "off" states. The high-density plasmonic antenna array structure will be promising for engineering applications in optical magnetism, magnetoplasmonics, optical trapping, and massively parallel ultrasensitive differential detection of molecular fingerprints.