A new mechanism to suppress the homogeneous gain broadening for stable multi-wavelength erbium-doped fiber laser

A suppressant effect of wavelength competition for multi-wavelength lasing oscillations is experimentally demonstrated in an ordinary erbium-doped fiber laser (EDFL). The polarization hole burning is exploited by a segment of erbium-doped fiber (EDF) coiled round the plates of the three-loop polarization controller. The mechanism to suppress the wavelength competition is discussed in detail. Results show that the mechanism is helpful to obtain stable multi-wavelength lasing oscillations at room temperature in the EDFL. By properly adjusting the comb filter, three-wavelength and tunable dual-wavelength lasing oscillations have been achieved. The power fluctuation is measured to be less than 0.75 dB over 30 min for all the multi-wavelength lasing oscillations obtained in the experiment. The 3 dB bandwidth of each lasing oscillation is 0.01 nm and the 30 dB bandwidth is 0.10 nm. The side mode suppression ratio (SMSR) of the three-wavelength lasing oscillation is more than 45 dB and that of the dual-wavelength lasing oscillations is more than 50 dB.