Generation of Q-switched-mode-locked operations in Er-doped fiber laser based on dispersion compensating fiber saturable absorber

Abstract In our work, the stable Q-switched-mode-locked (QML) operations were generated in Er-doped fiber laser based on dispersion compensating fiber (DCF) saturable absorber (SA) for the first time. Firstly, the dissipative soliton mode-locked operation was achieved in fiber laser without DCF. After that, the DCFs with different lengths were separately added into fiber laser to gradually optimize the cavity, and QML operations could be observed. When the length of DCF was 5 m, the stable QML operations at the Q-switching envelope frequency of 72.84 kHz was obtained under the pump power of 637 mW. The maximum Q-switching envelope energy was 204 nJ which was 80 times higher than pulse energy of dissipative soliton, and the pulse width was 455.7 fs which was almost one seventh of that of dissipative soliton. To our knowledge, 455.7 fs is the shortest width of a single pulse at the peak position of the temporal envelope so far. These results indicate that DCF has excellent performance in obtaining QML operations.