Recent Advances on Mid-Infrared Fiber Devices Based on Fluoride Glasses

Mid-infrared wavelength technology offers exciting opportunities for innovative photonic applications in medicine, telecommunications, material processing, environmental and chemical monitoring. The full development of optical fiber-based components is essential to enhance mid-infrared technology to the market level and to improve the flexibility of the related system. This will allow to eliminate bulky free-space optics, improving robustness and efficiency. Mid-infrared fiber lasers are crucial for these applications but remain in an early stage compared to mature silica-based fiber lasers, operating in the near-infrared. Significant progress has been made in the development of mid-infrared fiber components, including fiber couplers, fiber Bragg gratings and long-period gratings in fluoride glass, fluoride-to-fluoride and silica-to-fluoride splicing. Despite these advancements, further efforts are required to increase the technology readiness level and drive its commercialization. The aim of this manuscript is to review the recent breakthroughs and illustrate the remaining gaps/challenges in developing fiber-based mid-infrared technology.