Advances in mid-infrared spectroscopy enabled by supercontinuum laser sources

Supercontinuum sources are all-fiber pulsed laser-driven systems that provide high power spectral densities within ultra-broadband spectral ranges. The tailored process of generating broadband, bright, and spectrally flat supercontinua-through a complex interplay of linear and non-linear processes-has been recently pushed further towards longer wavelengths and has evolved enough to enter the field of mid-infrared (mid-IR) spectroscopy. In this work, we review the current state and perspectives of this technology that offers laser-like emission properties and instantaneous broadband spectral coverage comparable to thermal emitters. We aim to go beyond a literature review. Thus, we first discuss the basic principles of supercontinuum sources and then provide an experimental part focusing on the quantification and analysis of intrinsic emission properties such as typical power spectral densities, brightness levels, spectral stability, and beam quality (to the best of the authors' knowledge, the M-2 factor for a mid-IR supercontinuum source is characterized for the first time). On this basis, we identify key competitive advantages of these alternative emitters for mid-IR spectroscopy over state-of-the-art technologies such as thermal sources or quantum cascade lasers. The specific features of supercontinuum radiation open up prospects of improving well-established techniques in mid-IR spectroscopy and trigger developments of novel analytical methods and instrumentation. The review concludes with a structured summary of recent advances and applications in various routine mid-IR spectroscopy scenarios that have benefited from the use of supercontinuum sources. (C) 2022 Optica Publishing Group under the terms of the Optica Open Access Publishing Agreement

Automated summary

Supercontinuum sources are fiber-based pulsed laser systems that generate high power spectral densities across a wide spectral range. This review discusses the current state and perspectives of supercontinuum technology in mid-infrared (mid-IR) spectroscopy. The article first explains the basic principles of supercontinuum sources and provides experimental analysis of their emission properties, such as power spectral densities, brightness levels, spectral stability, and beam quality. The authors identify the competitive advantages of supercontinuum sources over thermal sources or quantum cascade lasers in mid-IR spectroscopy. The unique features of supercontinuum radiation offer opportunities for improving established techniques and developing new analytical methods and instruments. The review concludes with a summary of recent advances and applications of supercontinuum sources in various mid-IR spectroscopy scenarios.