Supercontinuum generation in an Er-doped figure-eight passively mode-locked fiber laser

A supercontinuum source based on a figure-eight Er-doped fiber ring cavity has been experimentally demonstrated with low repetition rate. The proposed configuration of the experiment is a figure-eight fiber laser grounded in Nonlinear Optical Loop Mirror (NOLM) technique. A broad spectrum of approximately 410 nm spanning the range 1315-1725 nm at the level of 30 dB can be obtained at a given average power of 2.6 mW and without any amplifier. Such wide spectrum can be directly achieved in the fiber resonator, which makes the structure compact and robust. By changing the pump power, the temporal pulse width can be adjusted accordingly. The pulse width is about 4 ns at the pump power of around 240 mW. The broadband spectrum was generated directly from the fiber resonator, which can be easily applied in numerous areas, such as the optical frequency metrology, optical spectroscopy, optical coherence tomography, optical communications, and medical sciences.