We present a terahertz (THz) scattering near-field optical microscope (s-SNOM) based on a quantum cascade laser implemented as both source and detector in a self-mixing scheme utilizing resonant quartz tuning forks as a sensitive nanopositioning element. The homemade s-SNOM, based on a resonant tuning fork and metallic tip, operates in tapping mode with a spatial resolution of ∼78 nm. The quantum cascade laser is realized from a bound-to-continuum active region design with a central emission of ∼2.85 THz, which has been lens-coupled in order to maximize the feedback into the laser cavity. Accordingly, the spatial resolution corresponds to >λ/1000. The s-SNOM has been used to investigate a bidimensional plasmonic photonic crystal and to observe the optical resonant modes supported by coupled plasmonic planar antennas, showing remarkable agreement with the theoretical predictions. The compactness, unique sensitivity, and fast acquisition capability of this approach make the proposed s-SNOM a unique tool for solid-state investigations and biomedical imaging.

中文翻译：

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量子级联激光的太赫兹等离子体共振的纳赫法。

我们提出了一种基于量子级联激光的太赫兹（THz）散射近场光学显微镜（s-SNOM），该量子级联激光在利用共振石英音叉作为敏感纳米定位元素的自混合方案中实现了源和探测器的作用。基于共振音叉和金属尖端的自制s-SNOM以轻敲模式工作，空间分辨率约为78 nm。量子级联激光器是由束缚到连续的有源区设计实现的，中心发射约为2.85 THz，已进行透镜耦合，以使进入激光腔的反馈最大化。因此，空间分辨率对应于>λ/ 1000。s-SNOM已用于研究二维等离激元光子晶体并观察耦合的等离激元平面天线所支持的光学共振模式，与理论预测非常吻合。这种方法的紧凑性，独特的灵敏度和快速的采集能力使所提出的s-SNOM成为用于固态研究和生物医学成像的独特工具。