提出了利用1.7 μm和2.3 μm双波长泵浦掺镝 (Dy) 氟化铟 (InF3) 光纤产生4.3 μm中红外激光的方案。计算了泵浦光功率、信号光功率以及粒子数密度在腔内的空间分布,数值分析了泵浦光功率、输出镜反射率、光纤长度、光纤损耗等对激光输出功率的影响。计算结果表明,双波长泵浦能有效地去除自终止效应,进而实现4.3 μm激光输出,激光输出功率主要取决于2.3 μm泵浦光功率。当1.7 μm泵浦光功率一定时,输出激光功率随2.3 μm泵浦光功率的增加呈线性增加;当2.3 μm泵浦光功率一定时,存在最佳的1.7 μm泵浦光功率,其使得激光输出功率最大。研究结论为在光纤中产生高功率连续波运转的4 μm波段激光提供了一种可行方案,该方案对利用双波长泵浦Dy∶InF3光纤激光器获得4 μm波段激光具有指导意义。

4.3 μm mid-infrared fiber lasers are produced by pumping Dy-doped InF3 with dual wavelengths of 1.7 μm and 2.3 μm. The spatial distributions of pump light power, signal light power and population density in the cavity are calculated, and the influences of pump light power, reflectivity of the output mirror, fiber length, and fiber loss on output laser power are numerically analyzed. The calculation results show that the self-termination effect can be effectively eliminated by dual-wavelength pumping, and the 4.3 μm laser output can be realized. The laser output power mainly depends on the power of 2.3 μm pump laser. When the 1.7 μm pump laser power is fixed, the laser output power increases linearly with the increase of the 2.3 μm pump laser power. When the 2.3 μm pump laser power is fixed, the optimal 1.7 μm pump laser power is obtained, which makes the laser output power maximum. The study results provide a feasible scheme for the operation of a 4 μm high-power continuous-wave fiber laser, which is instructive for obtaining 4 μm lasers via dual-wavelength pumped Dy∶InF3 fiber laser.