High-resolution antenna near-field imaging and sub-THz measurements with a small atomic vapor-cell sensing element

TL;DR

This paper demonstrates high-resolution near-field imaging and sub-THz electric field measurements using small atomic vapor cells, achieving sub-wavelength spatial resolution and extending measurements into the sub-THz range.

Contribution

It introduces a compact atomic vapor-cell sensor capable of imaging and measuring electric fields at both microwave and sub-THz frequencies with high spatial resolution.

Findings

Achieved λ/10 spatial resolution in near-field imaging.

Measured electric fields from 72 to 240 V/m at 13.49 GHz.

Extended electric field measurements to 255 GHz in the sub-THz range.

Abstract

Atomic sensing and measurement of millimeter-wave (mmW) and THz electric fields using quantum-optical EIT spectroscopy of Rydberg states in atomic vapors has garnered significant interest in recent years towards the development of atomic electric-field standards and sensor technologies. Here we describe recent work employing small atomic vapor cell sensing elements for near-field imaging of the radiation pattern of a K$_u$-band horn antenna at 13.49 GHz. We image fields at a spatial resolution of $\lambda/10$ and measure over a 72 to 240 V/m field range using off-resonance AC-Stark shifts of a Rydberg resonance. The same atomic sensing element is used to measure sub-THz electric fields at 255 GHz, an increase in mmW-frequency by more than one order of magnitude. The sub-THz field is measured over a continuous $\pm$100 MHz frequency band using a near-resonant mmW atomic transition.