Mid-infrared (Mid-IR) fiber lasers and amplifiers have gained significant attention due to their potential applications in various fields, including spectroscopy, sensing, and materials processing. However, the efficient coupling of pump light into these Mid-IR fibers remains a critical challenge. Traditional pump combiners often involve complex fabrication processes and can suffer from low coupling efficiencies.
New research presents a novel pump combiner design that addresses these limitations. The proposed design utilizes a side-polished silica-fluoride multimode fiber to effectively couple pump light from a standard silica fiber into a fluoride fiber. The side-polishing technique selectively removes the cladding from one side of the silica-fluoride fiber, allowing direct contact between the silica fiber’s core and the fluoride fiber’s core.
The direct contact between the cores of the two fibers enables efficient power transfer, leading to significantly higher coupling efficiencies than traditional methods.
The side-polishing process eliminates the need for complex thermal post-processing steps, making the fabrication process more straightforward and cost-effective.
The design can be adapted to various pump wavelengths and fiber types, providing flexibility for different mid-IR laser applications.
The authors demonstrated the effectiveness of the side-polished silica-fluoride fiber pump combiner by achieving a coupling efficiency exceeding 80% at a pump wavelength of 980 nm. Furthermore, they successfully integrated the pump combiner into a linear Er-doped fiber laser cavity, enabling continuous-wave laser operation at central wavelengths of 2731 nm and 2781 nm with an output power of 0.87 W.
The side-polished silica-fluoride fiber pump combiner represents a promising approach for practical mid-IR fiber laser and amplifier development. Its high coupling efficiency, simplified fabrication process, and versatility make it a valuable tool for researchers and engineers in this field.
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