An L-band single-longitudinal-mode (SLM) erbium-doped fiber laser (EDFL) is proposed and experimentally demonstrated to exhibit an ultranarrow linewidth and a high optical signal-to-noise ratio. A multistage filter, which is composed of a thin film filter, a fiber Bragg grating, and a saturation absorption, is utilized as an effective mode-selecting filter to achieve an SLM EDFL. The SLM EDFL with an ultranarrow linewidth of 205 Hz is obtained at the measurement resolution bandwidth of 100 Hz. In addition, the stability performance of the EDFL is measured during 30 min. The maximum fluctuations of the center wavelength and the output power of the proposed EDFL are 0.04 nm and 0.01 dB.

中文翻译：

---

基于多级滤波器的超窄线宽L波段单纵模掺铒光纤激光器

提出并实验证明了 L 波段单纵模 (SLM) 掺铒光纤激光器 (EDFL) 具有超窄线宽和高光信噪比。由薄膜滤波器、光纤布拉格光栅和饱和吸收组成的多级滤波器用作有效的模式选择滤波器来实现 SLM EDFL。在 100 Hz 的测量分辨率带宽下获得具有 205 Hz 超窄线宽的 SLM EDFL。此外，EDFL 的稳定性性能是在 30 分钟内测量的。所提出的 EDFL 的中心波长和输出功率的最大波动为 0.04 nm 和 0.01 dB。