To accomplish single-longitudinal-mode (SLM) output and continuous wavelength selection, an erbium-doped fiber (EDF) quad-ring (QR) laser is presented and experimentally examined. The designed QR scheme can induce a mode-filter effect to compress dense multi-mode oscillation, narrow laser linewidth and flatten power output simultaneously. Hence, the attained optical signal to noise ratio (OSNR) and output power are between in an obtainable tunability bandwidth of 1524.0 to 1569.0 nm. In addition, the observed output characteristics of stability, flatness and linewidth of the fiber laser are also investigated and discussed.

中文翻译：

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基于四环的光纤激光器，可切换且稳定的单纵模运行

为了完成单纵模（SLM）输出和连续波长选择，提出并进行了掺examined光纤（EDF）四环（QR）激光器的测试。设计的QR方案可以引起模式滤波器效应，以压缩密集的多模振荡，同时缩小激光线宽和使功率输出平坦。因此，所获得的光信噪比（OSNR）和输出功率在1524.0至1569.0 nm的可获得的可调带宽内。此外，还研究和讨论了所观察到的光纤激光器的稳定性，平坦度和线宽输出特性。