  Noise-like pulses (NLP) are extremely sought after in many fields. Here, we
experimentally and numerically investigated the generation of noise-like pulses
in an all-normal-dispersion fiber laser with weak spectrum filtering. With the
insertion of the grating as a tunable spectrum filter, the laser operates at a
stable dissipative soliton state with a 3.84 ps duration. Replacing the grating
with a mirror, NLPs with double-scale intensity autocorrelation trace is
ultimately attained. Numerical simulations are performed in detail and
demonstrated that with the absence of a spectrum filter, the stable state
cannot be established but form the random pulse cluster. The random pulse
cluster achieves dynamic stability with suitable feedback, and the NLP is
ultimately generated. The NLP here is directly evolved by the initial noise,
and no other states occur during its evolution. These explorations could deepen
the understanding of NLP and enrich the complex dynamics of the ANDi ultrafast
fiber laser.
