Opt Express. 2021 May 24;29(11):17365-17374. doi: 10.1364/OE.425123.
We propose a nanoplasmonic interferometric biosensor, which exploits the selective excitation of multipolar plasmonic modes in a nanoslit to provide a novel scheme for highly-sensitive biosensing. In this design, two counter-propagating surface plasmon polaritons interfere at the location of the nanoslit, selectively exciting the dipolar and quadrupolar modes of the structure depending on the phase relationship induced by the analyte. The contrasting radiation patterns produced by these modes result in large changes in the angular distribution of the transmitted light that depends on the analyte concentration. The resultant far-field is numerically modeled and the sensing performance of the structure is assessed, resulting in maximum bulk and surface sensitivities of S = 1.12 × 10 deg/RIU and S = 302 deg/RIU, respectively, and a bulk-sensing resolution of the order of 10 RIU. The design allows ample control over the trade-off between operating range and resolution through the slit's width, making this platform suitable for a broad range of sensing requirements.
我们提出了一种纳米等离子体干涉生物传感器，该传感器利用纳米狭缝中多极等离子体模式的选择性激发，为高灵敏度生物传感提供了一种新方案。在该设计中，两个反向传播的表面等离激元在纳米狭缝处发生干涉，根据分析物引起的相位关系选择性地激发结构的偶极子和四极子模式。这些模式产生的对比辐射模式导致传输光的角分布发生大的变化，该变化取决于分析物的浓度。对产生的远场进行数值建模，并评估结构的传感性能，从而分别获得体灵敏度和表面灵敏度的最大值 S = 1.12×10°/RIU 和 S = 302°/RIU，以及约 10 RIU 的体灵敏度分辨率。通过狭缝的宽度，该设计可以充分控制工作范围和分辨率之间的权衡，使该平台适用于广泛的传感要求。
