High-SNR noise-like pulse generation from an all-polarization-maintaining mode-locked thulium-doped fiber laser

We demonstrate an all-polarization-maintaining passively mode-locked thulium-doped fiber laser based on a nonlinear optical loop mirror. Based on the characteristic autocorrelation trace with a nanosecond-scale pedestal and a 285-fs coherent spike, it is determined that the mode-locked laser outputs noise-like pulses. Benefiting from the all-polarization-maintaining structure, the laser exhibits significantly improved stability, with an output fluctuation of merely 0.11% over 30 min and a high signal-to-noise ratio of 73 dB. This performance provides a high-quality laser source for precision and high-end applications.