Observation of a giant-chirp dissipative soliton and near chirp-free pulse in a slight-normal-dispersion fiber laser

We reported a switchable giant-chirp (GC) dissipative soliton and near-chirp-free (NCF) pulse in a slight-normal-dispersion fiber laser by tuning the pump power. The GC dissipative soliton exhibits a quasi-rectangular spectrum with bandwidth of 9 nm and duration of 8 ps. The time bandwidth product (TBP) is calculated as 8.8, indicating that the dissipative soliton is highly chirped. The NCF pulse has a bandwidth of 2.5 nm and a duration of 1.8 ps, which gives a TBP of 0.55, suggesting that the pulse almost is chirp free. Our numerical simulations confirm the experimental observations, and demonstrate that the operation state of dissipative system is very sensitive to the pump strength.