Three-step staircase-like pulses generation in a butterfly-shaped mode-locked fiber laser

We experimentally observed three-step staircase-like pulses (TSSLP) delivered from a butterfly-shaped mode-locked fiber laser An integrated twin nonlinear amplifying loop mirrors (NALM) incorporating highly nonlinear fibers (HNLF 65, 52 m) acts as a homogeneous hybrid-like artificial saturable absorber (HH-SA). With the most available pump power, the obtained sub-stairs in TSSLP with 10.06, 9.61, 12.59 ns durations and 0.33, 3.46 and 5.38 W peak intensities at 1.23 MHz, respectively. The second-peak can be tuned from 0.1 to 3.46 W while the third-duration ranging from 9.86 to 14.12 ns. The achievements reveal that the proposed HH-SA scheme creates effective intensity discrimination while enjoying more consistent properties. It provides more flexible transfer curve and pulse-shaping mechanism, with novel features to meet the requirements of various engineering customizations. The versatility and stability of the HH-SA device, make it highly attractive as a stable platform for studying new pulses together with nonlinear interaction dynamics in fundamental physics.