Recent Advances in Mid-Infrared and Terahertz Dual-Comb Spectroscopy

SHANNON, CLARE, IRELAND, October 13, 2026 /CourierPR/ -- Recent progress in dual-comb spectroscopy (DCS) has expanded the capabilities of this technology into the mid-infrared and terahertz regions, according to a new publication from Opto-Electronic Technology.

DCS combines the precision of optical frequency combs with rapid spectral acquisition, enabling high-precision measurements and fast data collection. This technology has found applications in atmospheric monitoring, trace-gas detection, combustion diagnostics, industrial process monitoring, biomedical analysis, and fundamental studies of molecules. The mid-infrared region, with its strong molecular vibrations, is particularly valuable for identifying different molecules, while the terahertz region provides complementary information from molecular rotations and other low-energy motions.

Generating broad and stable frequency combs in the mid-infrared and terahertz regions remains challenging due to fewer suitable lasers and optical materials, as well as losses and limitations in light conversion. Researchers have developed several approaches to address these challenges, including nonlinear optical conversion, optical parametric devices, quantum cascade lasers, and integrated photonic technologies. These technologies offer different advantages in terms of spectral coverage, stability, power, and system complexity.

The review, co-authored by researchers from the research groups of Prof. Heping Zeng and Prof. Ming Yan at East China Normal University, in collaboration with Prof. Hua Li’s group at the Shanghai Institute of Microsystem and Information Technology, Chinese Academy of Sciences, and Prof. Min Li’s group at the University of Shanghai for Science and Technology, systematically summarizes the major technological approaches, representative advances, and future directions in mid-infrared and terahertz DCS.

For mid-infrared DCS, the review focuses on several key approaches, including difference-frequency generation, optical parametric oscillators, quantum cascade lasers, and integrated photonic platforms. Difference-frequency generation can extend mature near-infrared comb technology into the mid-infrared region, providing broad wavelength coverage and high coherence. Optical parametric oscillators offer high output power and broad tunability, while quantum cascade lasers directly generate combs in the molecular fingerprint region and enable compact, electrically driven systems. Integrated photonic technologies, such as microresonators and nonlinear waveguides, are further promoting system miniaturization and integration.

In the terahertz region, the review summarizes major approaches based on femtosecond lasers, electro-optic frequency combs, and terahertz quantum cascade lasers. Femtosecond-laser-based approaches provide broad spectral coverage and densely spaced comb lines, while electro-optic combs offer high frequency stability and flexible electronic control. Terahertz quantum cascade lasers provide relatively high output power and strong potential for compact systems. Recent advances in self-detection and on-chip integration have further enabled quantum cascade laser devices to combine the functions of light source, local oscillator, and detector, opening new possibilities for simpler and more compact terahertz spectrometers.

Across the mid-infrared and terahertz regions, the review identifies several common challenges, including broader spectral coverage, more sensitive broadband detection, long-term mutual coherence, and improved system integration. It also highlights emerging quantum technologies as promising approaches for detecting weak spectroscopic signals and further enhancing the capabilities of DCS.

The research teams led by Prof. Heping Zeng and Prof. Ming Yan have made significant contributions to advanced precision spectroscopy and imaging technologies, with a particular emphasis on mid-infrared DCS and comb-enabled hyperspectral imaging for applications such as trace-gas detection and remote sensing. Their collaboration with Prof. Hua Li and Prof. Min Li has further extended DCS into the important terahertz region, contributing to advances in terahertz metrology and spectroscopy. Together, these teams have co-published more than 100 research papers in leading journals, including Nature Photonics, Nature Communications, and Light: Science & Applications, and have received the Shanghai Technical Invention First Prize (2024) and the First Prize for Scientific and Technological Progress in Chongqing (2024).

The article is published in Opto-Electronic Technology 2, 260015 (2026), with the DOI 10.29026/oet.2026.260015.