Near-field scanning optical microscopy (NSOM) enables observation of light-matter interaction with a spatial resolution far below the diffraction limit without the need for a vacuum environment. However, modern NSOM techniques remain subject to a few fundamental restrictions. For example, concerning the aperture tip (a-tip), the throughput is extremely low, and the lateral resolution is poor; both are limited by the aperture size. Meanwhile, with regard to the scattering tip (s-tip), the signal-to-noise ratio (SNR) appears to be almost zero; consequently, one cannot directly use the measured data. In this work, we present a plasmonic tip (p-tip) developed by tailoring subwavelength annuli so as to couple internal radial illumination to surface plasmon polaritons (SPPs), resulting in an ultrastrong, superfocused spot. Our p-tip supports both a radial symmetric SPP excitation and a Fabry–Pérot resonance, and experimental results indicate an optical resolution of 10 nm, a topographic resolution of 10 nm, a throughput of 3.28%, and an outstanding SNR of up to 18.2 (nearly free of background). The demonstrated p-tip outperforms state-of-the-art NSOM tips and can be readily employed in near-field optics, nanolithography, tip-enhanced Raman spectroscopy, and other applications.

中文翻译：

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具有超高分辨率，高通量和信噪比的近场等离子探头

近场扫描光学显微镜（NSOM）能够以远低于衍射极限的空间分辨率观察光与物质的相互作用，而无需真空环境。但是，现代NSOM技术仍然受到一些基本限制。例如，关于光圈尖端（a-tip），通过量极低，并且横向分辨率差。两者都受光圈尺寸的限制。同时，对于散射尖端（s-tip），信噪比（SNR）似乎几乎为零。因此，人们不能直接使用测量数据。在这项工作中，我们介绍了通过定制亚波长环而开发的等离激元尖端（p-tip），以便将内部径向照明耦合到表面等离激元极化子（SPPs），从而产生超强的超聚焦点。我们的p-tip既支持径向对称SPP激发，又支持Fabry-Pérot共振，实验结果表明，光学分辨率为10 nm，形貌分辨率为10 nm，吞吐量为3.28％，出色的SNR高达18.2。 （几乎没有背景）。演示的p-tip优于最新的NSOM尖端，可轻松用于近场光学，纳米光刻，尖端增强拉曼光谱和其他应用。