Influence of seed source on supercontinuum generated by amplified all-normal-dispersion mode-locked Yb-doped fiber laser

Supercontinuum (SC) source generated by amplified and dechirped all-normal-dispersion (ANDi) mode-locked Yb-doped fiber laser has many advantages, such as compact structure and low cost. The influences of output ports of the seed source, i.e. ANDi laser, on the SC, which is generated by amplified and dechirped output pulse from the ANDi oscillator, are investigated experimentally. Two output ports are considered, one of which is the conventional nonlinear polarization rotation (NPR) port and the other is extracted from a coupler after the NPR port. It is found that, the SC originated from the coupler port is much broader than that from the NPR port, which is validated by lots of experiments with different output parameters. Hence for the SC generation based on amplified ANDi laser, it is preferred to use the pulse of coupler port (i.e. pulse after NPR port) serving as the seed source.