Narrow Line-Width Ytterbium-Doped Fiber Ring Laser Based on Saturated Absorber

In this letter, a narrow line-width ytterbium-doped fiber ring laser with a fiber Bragg grating inside the cavity is proposed and experimentally demonstrated. In order to realize single longitudinal mode (SLM) output, an un-pumped ytterbium-doped fiber is used as an SLM selector. First, the effect of the coupler output ratio on the output power and the threshold power is discussed in this proposed laser, and the coupler output ratio of 30% is adopted at last. Furthermore, the spectrum and frequency spectra are analyzed to obtain the line width and frequency stability. Finally, the output power with fluctuation in half an hour is measured to evaluate the power stability. The results show that the output power of 7 mW, signal-to-noise ratio greater than 65 dB at 1069 nm, line width less than 500 Hz, and power stability below 1.5% can be achieved for the laser.