Use of proper cavity loss for a stable single-longitudinal-mode erbium fiber laser

A stable and selectable erbium-doped fiber (EDF) ring laser configuration with single-longitudinal-mode (SLM) output is proposed and demonstrated in this paper. In the proposed laser scheme, a proper cavity loss is utilized for significant suppression of the side mode. In the experiment, the different coupling ratios required to produce various cavity losses in the proposed fiber laser are analyzed. Here, to reach the wavelength selection, several fiber Bragg gratings (FBGs) and an optical tunable bandpass filter (OTBF) in the C-band range are employed for demonstration. In addition, the output performance with respect to stability and SLM in the proposed EDF ring laser are also investigated simultaneously.