High-energy mode-locked holmium-doped fiber laser operating in noise-like pulse regime

An all-fiber mode-locked holmium-doped fiber laser operating in the noise-like pulse regime is reported. Employing a nonlinear amplifying loop mirror as the artificial saturable absorber, the laser generates pulses with energy up to 280 nJ, which is, to the best of our knowledge, the highest pulse energy ever achieved from mode-locked holmium-doped fiber lasers. We also discover a peculiar mode-locking operation mode using the laser. The peculiar mode falls into the category of a noise-like pulse, while it possesses a number of unique features (strong spikes in the optical spectrum, high temporal coherence, and chair-like pulse profile) that are not observed in previous research works regarding noise-like pulse lasers.