The Design of 1200-1250nm Fiber Laser

To address the demand for efficient and compact light sources in the 1200-1250 nm spectral range for applications in biomedical imaging and nonlinear frequency conversion, this paper proposes a theoretical design and performance simulation scheme of a bismuth-doped fiber laser. A steady-state rate-equation model based on a quasi-four-level system is established, which comprehensively describes the power evolution of forward and backward pump and signal light within a linear cavity structure. The resulting two-point boundary value problem is solved numerically using MATLAB'sbvp4csolver. The simulation results indicate that the designed laser possesses excellent performance potential, clearly revealing the processes of pump attenuation and signal amplification within the cavity. The findings validate the effectiveness of the established model and quantitatively predict the feasibility of achieving high-efficiency operation from a 1200 nm bismuth-doped fiber laser. This work provides significant theoretical guidance and a design basis for the experimental fabrication, parameter optimization, and performance enhancement of fiber lasers in this spectral range.