Nanofocusing performance of plasmonic probes based on gradient permittivity materials
Nanofocusing performance of plasmonic probes based on gradient permittivity materials
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DOI：
10.1088/2040-8986/ac69f6
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发表时间：
2022-04
影响因子：
2.1
通讯作者：
Dongxue Wang;Ze Zhang;Jianwei Wang;Ke Ma;Hua Gao;Xi Wang
中科院分区：
文献类型：
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作者：
Dongxue Wang;Ze Zhang;Jianwei Wang;Ke Ma;Hua Gao;Xi Wang
探针是散射型扫描近场光学显微镜（s-SNOM）等光学扫描探针显微镜的核心部件。其聚集和定位光的能力决定了纳米级光谱的检测灵敏度。本文提出了一种由梯度介电常数材料（GPM）制成的新型等离子体探针，并对其纳米聚焦性能进行了理论和数值研究。与传统的等离子体探针相比，该探针至少具有两个突出的优点：第一，不需要额外的结构来激发表面等离子体激元或局域表面等离子体共振，简化了探针系统；第二，不需要额外的结构来激发表面等离子体激元或局域表面等离子体共振。其次，通过设计探针介电常数的分布，可以进一步显着增强锥形探针结构固有的纳米聚焦效应。因此，尖端顶点处的强近场增强和定位提高了 s-SNOM 的光谱灵敏度和空间分辨率。我们还通过数值证明了 GPM 探针及其增强的纳米聚焦效应可以通过具有设计的掺杂分布的传统半导体材料来实现。所提出的新型等离子体探针有望促进后续纳米级光谱学应用。
Probe is the core component of an optical scanning probe microscope such as scattering-type scanning near-field optical microscopy (s-SNOM). Its ability of concentrating and localizing light determines the detection sensitivity of nanoscale spectroscopy. In this paper, a novel plasmonic probe made of a gradient permittivity material (GPM) is proposed and its nanofocusing performance is studied theoretically and numerically. Compared with conventional plasmonic probes, this probe has at least two outstanding advantages: first, it does not need extra structures for surface plasmon polaritons excitation or localized surface plasmon resonance, simplifying the probe system; second, the inherent nanofocusing effects of the conical probe structure can be further reinforced dramatically by designing the distribution of the probe permittivity. As a result, the strong near-field enhancement and localization at the tip apex improve both spectral sensitivity and spatial resolution of a s-SNOM. We also numerically demonstrate that a GPM probe as well as its enhanced nanofocusing effects can be realized by conventional semiconductor materials with designed doping distributions. The proposed novel plasmonic probe promises to facilitate subsequent nanoscale spectroscopy applications.