Compact all-fiber broadband supercontinuum source based on fluorotellurite fiber

Mid-infrared (MIR) fiber-based supercontinuum (SC) sources, with their broadband spectral coverage, high coherence, and integrability, have shown great potential in molecular spectroscopy, environmental monitoring, remote sensing, and biomedical imaging. In particular, MIR sources enables strong molecular absorption and reduced scattering, which allows high-contrast, label-free imaging with enhanced sensitivity. Therefore, the development of compact and stable broadband MIR sources is of significant importance. In this work, we propose and experimentally demonstrate an all-fiber SC source based on fluorotellurite fiber. Compared with commonly used fluoride fibers, fluorotellurite fiber exhibits a higher damage threshold, broader transmission window, and lower hygroscopicity, making it well-suited for generating high-power and stable MIR laser output. The calculated nonlinear coefficient of the fiber is 19 W-1km-1 at 2 μm, and its low loss in the 2–4 μm region further supports efficient MIR generation. The system is pumped by amplified broadband nanosecond pulses covering 1.9–2.4 μm, where the wide spectral width and flat-top temporal profile of the pump improve both the flatness and spectral extension of the generated SC. By cascading a specially designed fluorotellurite fiber with a 20 μm core and triple-cladding structure, we achieve an SC spanning from 1.9 to 3.9 μm, with a 10 dB bandwidth of ~1400 nm, an average output power of 949 mW, and a power conversion efficiency of ~25%. The demonstrated source combines compactness, stability, and alignment-free operation, providing a reliable platform for MIR photonics. It is expected to play an important role in advancing biophotonics and other interdisciplinary applications.