Opt Express. 2023 Apr 10;31(8):13366-13373. doi: 10.1364/OE.484650.
To address a challenging problem of super-resolution terahertz (THz) endoscopy, in this paper, an antiresonant hollow-core waveguide was coupled with a sapphire solid immersion lens (SIL), aimed at subwavelength confinement of guided mode. The waveguide is formed by a polytetrafluoroethylene (PTFE)-coated sapphire tube, the geometry of which was optimized to ensure high optical performance. SIL was judiciously designed, fabricated of bulk sapphire crystal, and then mounted at the output waveguide end. Study of the field intensity distributions at the shadow side of the waveguide-SIL system revealed the focal spot diameter of ≃0.2λ at the wavelength of λ = 500 μm. It agrees with numerical predictions, overcomes the Abbe diffraction limit, and justifies super-resolution capabilities of our endoscope.
为了解决太赫兹（THz）内窥镜超分辨率的难题，本文将反共振空芯波导与蓝宝石固体浸没透镜（SIL）耦合，旨在实现导模的亚波长限制。该波导由聚四氟乙烯（PTFE）涂层蓝宝石管构成，其几何形状经过优化，以确保出色的光学性能。SIL 经过精心设计，由块状蓝宝石晶体制成，然后安装在输出波导端。对波导-SIL 系统阴影侧的场强分布研究表明，在波长为 λ=500μm 时，光斑直径约为 0.2λ。这与数值预测相符，克服了阿贝衍射极限，证明了我们内窥镜的超分辨率能力。
