Fig. 1. Schematic of the experimental setup for generating narrowband ERFL. ISO, isolator; FBG, fiber Bragg grating; WDM, wavelength division multiplexer; EDF, erbium-doped fiber; SMF, single-mode fiber; OC, optical coupler; OSA, optical spectrum analyzer; PD, photodetector; OSC, oscilloscope.

Fig. 2. Power and spectral features of the ERFL. (a) OSNR at a pump power of 1.0 W. (b) Output power versus pump power. (c) Output spectra at different pump powers. Inset: spectral details in the red dashed box. (d) Variation of 3 dB bandwidth of ERFL with pump power.

Fig. 3. (a) Temporal intensity dynamics at a pump power of 2.2 W. (b) Intensity PDFs of the ERFL with different pump powers. The black dashed line represents the exponential distribution.

Fig. 4. Experimental configuration for investigating dispersion’s effects. DCF, dispersion compensation fiber.

Fig. 5. (a) Temporal intensity dynamics and (b) intensity PDFs of the ERFL with different transmission distances in SMF.

Fig. 6. Intensity PDF alteration after dispersion compensation. (a) Insufficient compensation. (b) Exact compensation.

Fig. 7. Dispersion compensation inside the ERFL cavity.

Fig. 8. Optical spectra under different experimental conditions. (a) Optical spectra of the ERFL with different transmission distances in SMF. (b) Optical spectra after insufficient dispersion compensation. (c) Optical spectra after exact dispersion compensation. (d) Optical spectra with dispersion compensation inside the ERFL cavity.