Dark pulse emission in nonlinear polarization rotation-based mul...

We experimentally show dark pulse generation in all-normal dispersion multiwavelength erbium-doped fiber laser (EDFL) with a long cavity of figure-of-eight configuration. The EDFL generates a stable multiwavelength laser with 0.47 nm spacing at 24 mW threshold pump power, while the number of lines obtained increases with the pump power. A dark pulse emission is observed as the pump power is increased above 137 mW, with fundamental repetition rate of 29 kHz and pulse width of 2.7 μs. It is observ