Amplified spontaneous emission in high-power burst-mode fiber lasers

Burst-mode operation of ultrafast lasers is drawing much attention due to its substantial advantages in material processing, particularly in terms of ablation rates and efficiency. However, development of burst-mode lasers is in its infancy and in particular, fiber lasers that have been reported to date have operated at relatively low powers until recently. An important limitation arises from amplified spontaneous emission generation between the pulse bursts, which needs to be better understood. We report a detailed characterization of amplified spontaneous emission generation in a high-power, continuously pumped Yb-doped fiber laser. The laser system implements doping management for balanced mitigation of thermal and nonlinear effects. Furthermore, we present generation of pulse bursts with an average power as much as 145 W, which is the highest power generated from a burst-mode fiber laser, to the best of our knowledge. The average pulse energy is 14.5 mu J at 1 MHz. Pulses of 13 ps are generated directly from the laser without requiring external compression.