Multi-angle low-loss fusion splicing of soft-glass fibers for robust all-fiber mid-infrared laser systems

Fully fiber-based mid-infrared supercontinuum (MIR-SC) light sources demonstrate significant application potential in environmental monitoring, biomedical applications, and national defense security due to their outstanding advantages of high robustness and portability. However, the core challenge in realizing high-performance all-fiber systems lies in achieving low-loss, high mechanical strength fusion splicing between dissimilar materials such as silica fiber, energy-transfer fiber, and infrared nonlinear fiber. This paper presents the first, to the best of our knowledge, study to overcome the key technical challenges in achieving high-quality fusion splicing between multi-angle fluorotellurite (TBY) fibers and As₂S₃ fibers, silica fibers, and homogeneous TBY fibers. Results demonstrate that by optimizing the splicing process, the loss at TBY-As₂S₃ heterogeneous fusion points can reach 0.26 ± 0.02 dB with mechanical strength 270 g; the TBY-silica heterogeneous fusion point exhibits a loss of 0.24 ± 0.01 dB with mechanical strength 300 g; while the homogenous TBY-TBY splice achieves a low-loss of 0.063 ± 0.002 dB and mechanical strength exceeding 330 g. For the first time, to the best of our knowledge, high-performance fusion splicing between TBY-As₂S₃ fibers at an angle of 8° and between TBY-silica fibers at multiple tilt angles (6.5°, 12.4°, and 15.2°) is achieved. This work innovatively introduced and optimized tilted splicing technology, suppressing system reflected power to near-zero levels. This fully demonstrates the impact of this tilted structure on system stability and its application potential in high-power systems. It provides a robust and versatile technical solution for achieving highly stable, high-performance all-fiber MIR sources.