Photonic Terahertz Hyperspectral Imaging with Swept-Frequency Dual Combs

Abstract

Hyperspectral imaging is a spectroscopic imaging technique that allows for the reconstruction of the geometric structure and spectral features of objects. Particularly terahertz (THz) technology has emerged as a pivotal tool across various applications, ranging from non-ionizing gas sensing to cancer diagnosis and nondestructive artifact testing. However, contemporary terahertz imaging systems are still challenged by insufficient spectral accuracy and limited tuning range of THz sources. In this paper, for the first time, a swept-frequency dual-comb THz source with excellent frequency resolution and flexible tunability is proposed and demonstrated in applications of hyperspectral imaging. The swept-frequency dual-comb THz source is conceived by the photomixing of frequency-modulated continuous waves and dual electro-optic combs. As a pioneering approach, the swept-frequency dual-comb breaks the trade-off between spectral bandwidth and frequency resolution in dual-comb systems, achieving a frequency resolution of 50 MHz under a spectral bandwidth of over 100 GHz. These breakthroughs chart an exciting course toward the development of high-performance and user-friendly THz imaging systems, which hold great potential in applications such as security screening, chemistry, and biomedicine.