Wang Xin-Ke, Ye Jia-Sheng, Sun Wen-Feng, Han Peng, Hou Lei, Zhang Yan
Beijing Key Laboratory of Metamaterials and Devices, Key Laboratory of Terahertz Optoelectronics Ministry of Education, Department of Physics, Capital Normal University, Beijing, 100048, China.
Applied Physics Department, Xian University of Technology, Xian, Shaanxi, 710048, China.
Light Sci Appl. 2022 May 7;11(1):129. doi: 10.1038/s41377-022-00822-8.
Terahertz (THz) near-field microscopy retains the advantages of THz radiation and realizes sub-wavelength imaging, which enables applications in fundamental research and industrial fields. In most THz near-field microscopies, the sample surface must be approached by a THz detector or source, which restricts the sample choice. Here, a technique was developed based on an air-plasma dynamic aperture, where two mutually perpendicular air-plasmas overlapped to form a cross-filament above a sample surface that modulated an incident THz beam. THz imaging with quasi sub-wavelength resolution (approximately λ/2, where λ is the wavelength of the THz beam) was thus observed without approaching the sample with any devices. Damage to the sample by the air-plasmas was avoided. Near-field imaging of four different materials was achieved, including metallic, semiconductor, plastic, and greasy samples. The resolution characteristics of the near-field system were investigated with experiment and theory. The advantages of the technique are expected to accelerate the advancement of THz microscopy.
太赫兹（THz）近场显微镜保留了太赫兹辐射的优势并实现了亚波长成像，这使其能够应用于基础研究和工业领域。在大多数太赫兹近场显微镜中，太赫兹探测器或源必须靠近样品表面，这限制了样品的选择。在此，基于空气等离子体动态孔径开发了一种技术，其中两个相互垂直的空气等离子体重叠在样品表面上方形成一个交叉细丝，该交叉细丝调制入射太赫兹光束。因此，无需使用任何设备靠近样品即可观察到具有准亚波长分辨率（约为λ/2，其中λ是太赫兹光束的波长）的太赫兹成像。避免了空气等离子体对样品的损伤。实现了对包括金属、半导体、塑料和油腻样品在内的四种不同材料的近场成像。通过实验和理论研究了近场系统的分辨率特性。该技术的优势有望加速太赫兹显微镜的发展。
