Terahertz near-field microscopy based on an air-plasma dynamic aperture

• Published in: Light, science & applications science & applications, 2022-05, Vol.11 (1), p.129-129, Article 129
• Main Authors: Wang, Xin-ke, Ye, Jia-sheng, Sun, Wen-feng, Han, Peng, Hou, Lei, Zhang, Yan
• Format: Article
• Language: English
• Subjects: 639/624/1107/510; 639/766/400/561; Applied and Technical Physics; Atomic; Classical and Continuum Physics; Lasers; Microscopes; Microscopy; Molecular; Optical and Plasma Physics; Optical Devices; Optics; Photonics; Physics; Physics and Astronomy; Wavelength
• ISSN: 2047-7538; 2095-5545; 2047-7538
• 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. A THz near-field technique was proposed based on an air-plasma dynamic aperture, which can achieve sub-wavelength THz imaging without approaching the sample with any devices.