针对输出耦合镜旋转调谐时输出光束方向变化问题，设计了一种光纤位置平移、而调谐输出光束方向不变的光纤激光器系统。运用光栅方程，分析了光纤平移的调谐机理；采用输出与反馈光束耦合模型，分析了输出增益线宽随光纤位置、光束半径的变化。理论分析表明：该光纤激光器可获得线宽小于0.2 nm的调谐激光输出。实验结果表明，该激光器在波长为1543.446 nm处获得的调谐输出功率最大，达到470 mW，计算的斜率效率为23.9 %；整个调谐区域达到36 nm，调谐范围内激光的3 dB 线宽小于0.08 nm。

Aim at the change problem of output beam direction when using a rotated out-coupling mirror as the tunable element, a laser system with constant direction of the tuned output beam was designed by shifting the gain fiber position. According to the grating equation, the tunable mechanism of shifting gain fiber was analyzed. Further, the changes of gain linewidth with the fiber position and mode field radius were also analyzed by means of the coupling model of the output and feedback beams, which show that the gain linewidth of the output beams for the designed fiber laser was less than 0.2 nm. The experimental results show that the maximum output power is 470 mW at 1543.446 nm , with a slope efficiency of 23.9%. The experiment also shows that the wavelength tunable range is 36 nm, and the 3 dB linewidths in the whole tunable range are less than 0.08 nm.