Theoretical study on multi-range pulsewidth tuning in a dissipative soliton laser mode-locked by a Dirac semimetal

Ultrashort pulse fiber lasers with tunable pulsewidth have a wide range of applications in telecommunication, micro-fabrication, and nonlinear bioimaging. In this paper, we reported the simulation of multi-range pulsewidth-tunable ultrashort pulse laser generation in a mode-locked Er3+ doped fiber laser based on Cd3As2 as a saturable absorber (SA) for the first time. By changing the modulation depth (MD) of Cd3As2 SA from 35% to 75% at the different net normal dispersion, the pulsewidth of the fiber laser is tuned from 4.07 to 48.9 ps. In our simulation, the maximum single tunable range (20.3–48.9 ps) can be obtained when we use a long normal dispersion fiber to increase the net normal dispersion of the cavity, and the minimum tunable range of 1.68–2.45 ps is also achieved by further simultaneously decreasing the cavity length and the net normal dispersion. This model of a mode-locked fiber laser controlled by the MD of Cd3As2 SA provides a simple, reliable, and low-cost solution for a variety of applications that require width-tunable pulses.