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

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 A/2, where A 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.

Automated summary

A technique based on air-plasma dynamic aperture was developed to achieve THz imaging with quasi sub-wavelength resolution, without the need to approach the sample with any devices and avoiding damage to the sample. This technique has the potential to accelerate the advancement of THz microscopy by enabling near-field imaging of different materials.