单纵模掺铒光纤激光器在光通信和光传感等方面有着广泛的应用前景。设计了一种新型的光纤激光器,在光纤环形镜中嵌入未抽运的掺铒光纤作为可饱和吸收体以抑制多纵模,用光纤环谐振腔作为滤波器抑制拍频噪声,用光纤光栅作为波长选择器件,最终得到了单纵模输出并消除了拍频噪声。使用零拍法测量其线宽小于频谱仪的低频极限5 kHz。实验结果证明了可饱和吸收体和光纤环的功能。

Single-longitudinal-mode (SLM) fiber lasers are attractive for optical communications and optical sensors. The fiber laser usually operates in multimode and beating noises are a serious problem due to beat between laser mode and amplified spontaneous emission mode. A novel Er-doped single-mode fiber ring laser was demonstrated. In this laser, an unpumped Er-doped fiber was served as a saturable absorber to ensure the SLM operation, and a fiber ring resonator filter was used to suppress the beating noise. With a fiber Bragg grating (FBG) as a selective wavelength component, single mode output without beating noise is obtained experimentally. Measured linewidth is narrower than 5 kHz by using a homodyne setup, which is limited by the radio-frequency (RF) analyzer. The functions of saturable absorber and fiber ring resonator are proved.