Raman-enhanced multicolor pulses in dissipative soliton mode-locked ring-cavity fiber laser based on GIMF-SA

The stable multicolor complex with dissipative solitons (DS) and Raman pulses (RP) is experimentally demonstrated in the mode-locked Yb-doped ring-cavity fiber laser based on a graded-index multimode fiber (GIMF) as a saturable absorber (SA). The central wavelength of DS and RP are 1032.01 nm and 1078.08 nm, respectively. By wavelength-dividing the output pulse, it is found that the pulse width and period of DS and RP are consistent with the total pulse, but the DS pulse intensity is larger than that of RP. The single-to-noise ratio (SNR) of DS is about 55 dB, which is large than that of the complex pulse. We further improve the stability of the mode-locked state in the cavity by separating the RP out of the cavity. The experimental results obtained by two methods of separating pulses indicates that the stimulated Raman scattering (SRS) effect destabilizes the DS mode-locked fiber laser and doesn’t disrupt the single pulse generation regime.