Mode-resolved Direct Frequency Comb Cavity Ring-Down Spectroscopy with a Mid-Infrared Chip-Scale Interband Cascade Laser

TzuLing Chen^1*, Charles R. Markus², Yi-Jan Huang¹, Łukasz A. Sterczewski³, Douglas C. Ober², Mitchio Okumura²

¹Department of photonics, National Yang-Ming Chiao-Tung University, Hsinchu, Taiwan
²Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, CA, USA
³Electronics, Photonics and Microsystems, Wroclaw University of Science and Technology, Wyb. Wyspianskiego, Poland

* Presenter:TzuLing Chen, email:tlc@nycu.edu.tw

Optical frequency comb (OFC) spectroscopy has become a valuable tool in many fields due to its ability to detect multiple species with high precision over a broad spectral range. The potential of chip-scale OFCs in creating miniaturized molecular sensors is particularly exciting. However, when seeking high sensitivity, previous chip-scale comb spectrometer demonstrations have been limited to direct absorption techniques using either single-pass or multi-pass cells. In this work, we demonstrate a new approach by coupling a chip-scale 3.3 μm mid-infrared comb into a high-finesse cavity and using cavity ring-down techniques in a Vernier configuration. This enables us to capture mode-resolved spectra with millisecond resolution, expanding the potential of chip-scale OFC spectroscopy. The successful integration of the chip-scale optical frequency comb with the cavity ring-down technique opens up the possibility of miniaturized spectrometers and high-throughput molecular detection in sensitive fingerprinting applications.

Keywords: comb, infrared, laser spectroscopy, cavity ring down spectroscopy, Vernier