A low-threshold and simple structure switchable multi-wavelength fiber laser based on random distributed feedback (RDFB) is presented. The experiment setup incorporates a two-stage Sagnac fiber loop mirror, an 8 m long erbium-doped fiber (EDF), and a 25 km long single-mode fiber (SMF). The SMF provides RDFB via Rayleigh scattering. Due to the implementation of the half-open cavity structure and the gain generated by the EDF, the laser threshold can be significantly suppressed to 60 mW, and the slope efficiency of output lasing power against pump power is ∼0.9%. By adjusting the polarization controllers of the proposed two-stage Sagnac loop mirror, single-, double-, triple-, and quadruple-wavelength lasing channels in the range of 1527–1534 nm are achieved. In the case of quadruple-wavelength channel lasing, the optical signal noise ratio is up to 33 dB under the 180 mW pump power. The proposed random fiber laser can be applied in distributed sensing systems and biomedical imagin...

中文翻译：

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包含两级Sagnac滤波器的可切换多波长掺do随机分布反馈光纤激光器

提出了一种基于随机分布反馈（RDFB）的低阈值，结构简单的可切换多波长光纤激光器。实验设置包括一个两级Sagnac光纤环形镜，一个8 m长的掺-光纤（EDF）和一个25 km长的单模光纤（SMF）。SMF通过瑞利散射提供RDFB。由于采用了半开腔结构和EDF产生的增益，可以将激光阈值显着抑制到60 mW，输出激光功率相对于泵浦功率的斜率效率约为0.9％。通过调整所提议的两级Sagnac环形镜的偏振控制器，可以实现1527–1534 nm范围内的单波长，双波长，三波长和四波长激光通道。在四波长信道发射的情况下，在180 mW泵浦功率下，光信号噪声比高达33 dB。提出的随机光纤激光器可以应用于分布式传感系统和生物医学成像中。