Near-field terahertz probes with room-temperature nanodetectors for subwavelength resolution imaging

TL;DR

This paper presents a novel near-field terahertz imaging technique using room-temperature nanodetectors with subwavelength resolution, enabling compact, versatile systems that bridge nanoscale and diffraction-limited imaging.

Contribution

It introduces a new architecture that exploits evanescent THz fields and asymmetric electrodes to achieve room-temperature, subwavelength resolution imaging with a novel detector design.

Findings

Achieved sub-wavelength resolution coherent imaging at 3.4 THz.

Demonstrated room-temperature operation of THz near-field probes.

Enabled compact and versatile THz imaging systems.

Abstract

Near-field imaging with terahertz (THz) waves is emerging as a powerful technique for fundamental research in photonics and across physical and life sciences. Spatial resolution beyond the diffraction limit can be achieved by collecting THz waves from an object through a small aperture placed in the near-field. However, light transmission through a sub-wavelength size aperture is fundamentally limited by the wave nature of light. Here, we conceive a novel architecture that exploits inherently strong evanescent THz field arising within the aperture to mitigate the problem of vanishing transmission. The sub-wavelength aperture is originally coupled to asymmetric electrodes, which activate the thermo-electric THz detection mechanism in a transistor channel made of flakes of black-phosphorus or InAs nanowires. The proposed novel THz near-field probes enable room-temperature sub-wavelength resolution coherent imaging with a 3.4 THz quantum cascade laser, paving the way to compact and versatile THz imaging systems and promising to bridge the gap in spatial resolution from the nanoscale to the diffraction limit.