“…Practically, the homogeneous broadening and spatial-hole-burning effect of EDF and a long loop cavity in EDF-based laser leads to unstable multi-longitudinal-mode (MLM) oscillation [5]. To obtain the stable continuous-wave (CW) tunability and single-longitudinal-mode (SLM) in EDF based laser, there are several related researches have been proposed to suppress the densely MLM noises, such as using compound-ring configuration [6], [7], employing Rayleigh backscattering in tapered fiber [8], applying EDF-based saturation absorber (SA) [9], designing optical self-injection technique [10], [11], utilizing Sagnac-ring architecture [12], [13] and employing Mach-Zehnder interferometer [14]. Moreover, to achieve CW wavelength-tunability, fiber Bragg grating [15], tunable…”