Numerical Simulation of Bismuth-Doped Fiber in 1350-1400 nm Laser Emission

In recent years, fiber lasers have shown significant potential for applications in biomedical imaging and optical fiber communications. However, conventional rare-earth-doped fibers face challenges such as low efficiency and narrow bandwidth. Bismuth (Bi)-doped fibers have emerged as an ideal alternative due to their broadband luminescence characteristics (1100-1800 nm), but issues such as emission cross-section optimization and concentration quenching effects remain unresolved. Bismuth-doped phosphosilicate fibers (BPSFs) have attracted considerable attention for covering the second transmission window. Researchers worldwide have achieved gains exceeding 20 dB in the 1320-1460 nm band by refining fabrication techniques and pump structures. This study focuses on a three-level bismuth-doped fiber laser work in the 1350-1400 nm wavelength range. Through numerical simulations, the following results were obtained: The optical power generated by the laser exhibits a linear relationship with the input power. As the forward pump power propagates through the fiber, it undergoes exponential decay. The backward pump power remains negligible. The forward laser power follows a logarithmic growth distribution. The backward laser power demonstrates an exponential decay distribution. These findings provide theoretical support for the industrial application of fibers doped with bismuth and advance the expansion of the operational bandwidth of fiber amplifiers in communications, medical fields, and beyond.