Mid-infrared optical fiber Devices: Challenges, advances and applications

This review provides an overview on part of the several recent progresses in mid-infrared optical fiber devices, with a focus on enabling technologies and emerging applications. The mid-infrared spectral region is of particular interest due to its strong and selective molecular absorption, which is a key element for high-sensitivity applications such as gas sensing, chemical and biomedical sensing, and environmental monitoring. The paper first outlines the significance of the mid-infrared wavelength window and its application landscape. Then, it reports the state-of-the-art of mid-infrared optical sources, including those based on nonlinear frequency conversion and fiber laser architectures. Special emphasis is then placed on recent developments in fiber-based components that support the fabrication of compact, mechanically robust, and alignment-free, all-fiber mid-infrared systems. In particular, fluoride glass fibers, owing to their broad transmission wavelength range and low phonon energy, have emerged as a practical platform in this area. The review highlights the substantial research efforts devoted to improving the performance, fabrication, and integration of fluoride fiber technologies, which are expected to play a crucial role in the advancement of next-generation mid-infrared photonic systems.