High-Power Mid-Infrared Supercontinuum Light Source Based on High-Quality Fusion of Large-Diameter Silica Fiber and Fluorotellurite Fiber

Mid-infrared supercontinuum (MIR-SC) light sources have garnered significant attention in fields such as material detection and national defence. Currently, mid-infrared lasers suffer from issues including low output power, a narrow spectral range, and a short operational lifetime, which render them inadequate for practical applications. The efficient coupling of silica and soft-glass fibers is key to achieving a high-power, high-stability SC light source. We explore and apply asymmetric temperature gradient fusion splicing technology to complete the fusion splicing of large-diameter silica and large-diameter fluorotellurite (TBY) fiber, achieving a fusion point with low loss, ultra-high robustness, a high damage threshold, and low thermal sensitivity. By precisely controlling the temperature gradient, a high-quality fusion splice was achieved with a loss of 0.24 dB and a mechanical strength exceeding 300 g. The fusion point can withstand a transmission of 52.7 W at a wavelength of 2 μm, maintaining a temperature of 28.3°C without significant heating or damage. This confirms its ability to transmit a power of 50 W. Furthermore, we achieved an SC output of 21.54 W at a pump power of approximately 70 W by applying this stable, high-quality fusion technology to MIR-SC light sources. The resulting spectrum spans from 1.9 to 3.7 μm. Compared with butt coupling methods, the long-wavelength edge of the SC spectrum was extended by 420 nm and exhibits greater stability, demonstrating the essential role of fusion splicing technology in advancing high-power MIR-SC light sources.