Advances in mid-infrared spectroscopy enabled by supercontinuum laser sources

TL;DR

This paper reviews the development and application of supercontinuum laser sources in mid-infrared spectroscopy, highlighting their advantages, experimental properties, and potential to enhance existing and new analytical techniques.

Contribution

It provides a comprehensive analysis of supercontinuum sources' properties and compares them with traditional mid-IR emitters, including first-time characterization of the M2 factor for these sources.

Findings

Supercontinuum sources offer high spectral brightness and stability.

They outperform thermal sources and quantum cascade lasers in certain aspects.

Recent applications demonstrate their effectiveness in routine mid-IR spectroscopy.

Abstract

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 M2 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.