Multi-wavelength noise-like pulsed erbium-doped fiber laser

We proposed and demonstrated a multi-wavelength noise-like pulsed passive mode-locked erbium-doped fiber laser. The 980 nm semiconductor laser was used as the pump source and the erbium-doped fiber (EDF) with length of 2.5 m was used as the gain medium. The mode-locking operation was achieved by using a nonlinear amplifier loop mirror (NALM) structure. It is proved by self-correlation trace that the output pulse is a noise-like pulse. The 3-dB bandwidth of noise-like pulse is 17.2 nm, the side mode suppression ratio is 47.7 dB, the repetition rate is 5.434 MHz and the single pulse energy is 7.9 nJ. In order to achieve flat multi-wavelength output, a Sagnac ring interferometer was added to the NALM structure, and the flat multi-wavelength noise-like pulse was obtained with the number of maximum wavelength of 5 and the flatness of 1.995.