Real-Time Near-Field Terahertz Imaging with Atomic Optical Fluorescence

TL;DR

This paper introduces a novel method for real-time near-field terahertz imaging using atomic optical fluorescence from Rydberg atoms, enabling fast, distortion-free imaging of THz fields.

Contribution

The authors demonstrate THz-to-optical conversion with Rydberg atoms, allowing real-time imaging of THz fields without probe distortion or scanning, advancing near-field THz imaging technology.

Findings

Successful THz to optical conversion using Rydberg atoms

Real-time imaging of THz standing waves achieved

Calibration of THz field strength using atomic properties

Abstract

Terahertz (THz) near-field imaging is a flourishing discipline [1], with applications from fundamental studies of beam propagation [2,3] to the characterisation of metameterials [4,5] and waveguides [6,7]. Beating the diffraction limit typically involves rastering structures or detectors with length scale shorter than the radiation wavelength; in the THz domain this has been achieved using a number of techniques including scattering tips [8,9] and apertures [10]. Alternatively, mapping THz fields onto an optical wavelength and imaging the visible light removes the requirement for scanning a local probe, speeding up image collection times [11,12]. Here we report THz to optical conversion using a gas of highly excited `Rydberg' atoms. By collecting THz-induced optical fluorescence we demonstrate a real-time image of a THz standing wave and we use well-known atomic properties to calibrate the THz field strength. The mono-atomic gas does not distort the THz field and offers the potential to immerse structures within the THz-to-optical conversion medium.