Terahertz (THz) technology holds great potential across diverse applications, including biosensing and information communications, but conventional far-field techniques are limited by diffraction. Near-field optical microscopy overcomes this barrier through a sharp tip that concentrates incident THz waves into nanometric volumes, detecting scattered near-field to reveal nanoscale optical properties. However, owing to the large THz wavelengths, resonant surface waves arising on the tip and cantilever obscure the intrinsic response. Here we combine near-field microscopy with THz time-domain spectroscopy and implement time-domain filtering with an elongated cantilever to eliminate this artifact, achieving intrinsic nanospectroscopy and nanoimaging. By applying this technique, we distinguish and characterize historical pigments of an ancient sculpture, such as vermilion and red lead, on the nanoscale. We also unravel deep-subwavelength localized resonance modes in THz optical antennas, demonstrating capabilities for THz nanophotonics. Our work advances THz nanoimaging and nanospectroscopy techniques to probe intrinsic nanoscale THz light-matter interactions.

中文翻译：

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本征光-物质相互作用的时域滤波太赫兹纳米


太赫兹 （THz） 技术在包括生物传感和信息通信在内的各种应用中具有巨大潜力，但传统的远场技术受到衍射的限制。近场光学显微镜通过一个尖锐的尖端克服了这一障碍，该尖端将入射的太赫兹波集中到纳米级体积中，检测散射的近场以揭示纳米级光学特性。然而，由于太赫兹波长较大，针尖和悬臂上产生的共振表面波掩盖了本征响应。在这里，我们将近场显微镜与太赫兹时域光谱相结合，并使用细长的悬臂实现时域过滤以消除这种伪影，实现本征纳米光谱和纳米成像。通过应用这种技术，我们在纳米尺度上区分和表征古代雕塑的历史颜料，例如朱红色和红铅。我们还揭示了太赫兹光学天线中的深亚波长局域谐振模式，展示了太赫兹纳米光子学的能力。我们的工作推进了太赫兹纳米成像和纳米光谱技术，以探测本征纳米级太赫兹光物质相互作用。