Gaps in metal structures are accompanied by strong field enhancement (FE) and localized electromagnetic effects. However, completely different characteristics are presented when the microgaps and nanogaps in metallic structures are imaged using THz s-SNOM. We find that the near-field signal profile measured across the gap varies significantly with the ratio of the tip apex radius to the gap width. Increased (reduced) near-FE and a two-peak (one-peak) line profile are observed with microgaps (nanogaps). This phenomenon is caused by strong tip-gap interactions. In our full-wave simulations, we obtained near-field images of gap structures numerically, which were clearly reproduced practically.

金属结构中的间隙伴随着强场增强 (FE) 和局部电磁效应。然而，当使用太赫兹 s-SNOM 对金属结构中的微间隙和纳米间隙进行成像时，呈现出完全不同的特性。我们发现跨间隙测量的近场信号轮廓随尖端顶点半径与间隙宽度的比率而显着变化。使用微间隙（纳米间隙）观察到增加（减少）的近 FE 和双峰（一个峰）线轮廓。这种现象是由强烈的尖端间隙相互作用引起的。在我们的全波模拟中，我们以数值方式获得了间隙结构的近场图像，这些图像在实践中得到了清晰的再现。