Fast and compact time-resolved spectroscopy enabled by Quantum Walk Combs

Abstract: Optical frequency combs paved the way for fast and compact multi-component optical chemical analysis due to their broadband spectra. Dual-comb spectrometers embody this technology, but their design requires a pair of matched combs, adding complexity to the system. In this study, we propose and implement a scheme for a rapid, compact spectroscopic analyser that operates without moving components, leveraging the tunability and speed of a single quantum walk comb laser. Previously, these combs have been shown to deliver stable, tunable and broadband lasing. Here, a single quantum cascade laser-based comb emitting within the significant molecular fingerprint region of the mid-infrared spectrum was employed in a non-interferometric setup for targeted and non-targeted analysis of various organic solvent vapours. With a time resolution as small as 10 microseconds and a high dynamic range reaching three orders of magnitude in concentration, this approach is suitable for the real-time analysis of chemical kinetics.