A 1.8-µm tunable multiwavelength thulium-doped fiber laser based on a hybrid filter is proposed. In the designed ring-cavity fiber laser, the filter consists of one Sagnac loop and one dual-pass Mach–Zehnder filter. In the experiment, the lasing threshold is 155 mW, and a continuously tunable and stable single-wavelength laser could be realized with a minimum tuning interval of 2.1 nm within a scope of 22.5 nm. When an 1858-nm laser is obtained, the peak power fluctuation is less than 0.83 dB within 20 minutes at room temperature. By adjusting the polarization controller, stable dual-wavelength lasers are simultaneously achieved, and the peak power shift is less than 1.24 dB within a scan time of 20 minutes at room temperature. By changing the polarization state, stable triple-wavelength lasing is obtained, and the power fluctuation is less than 1.95 nm. In the experiment, the 3-dB linewidth of the laser is less than 0.4 nm.

提出了一种基于混合滤波器的1.8μm可调多波长掺-光纤激光器。在设计的环形腔光纤激光器中，滤波器由一个Sagnac环路和一个双通Mach–Zehnder滤波器组成。在实验中，激光阈值为155 mW，可以在22.5 nm范围内以2.1 nm的最小调谐间隔实现连续可调且稳定的单波长激光器。当获得1858 nm激光器时，室温下20分钟内峰值功率波动小于0.83 dB。通过调节偏振控制器，可以同时获得稳定的双波长激光器，并且在室温下20分钟的扫描时间内，峰值功率偏移小于1.24 dB。通过改变偏振态，可以获得稳定的三波长激光，功率波动小于1。95 nm。在实验中，激光器的3 dB线宽小于0.4 nm。