Hydrazone organics modulation for h-shaped nanosecond pulse generation in 1.3-km ultra-long mode-locked erbium-doped fiber laser

Abstract

We report an ultra-long erbium-doped fiber laser based on hydrazone organisms that generates a tunable h-shaped pulse at the trailing edge and can readily convert nanosecond pulses into h-shaped pulse. By changing the polarization state in the cavity of the ultra-long laser, the nanosecond pulse can be converted to an h-shaped pulse at a certain power level. At this time, the pump power is increased, ranging from 208.2 mW to 393.2 mW, and the pulse trailing edge can be tuned regularly, with a tuning range from 8.2 ns to 17.9 ns. The experimental results show that the variation of the h-shaped pulse along the width is related to the clamping effect of the peak power and the weak birefringence effect. In conclusion, the investigation of ultra-long laser resonators based on real saturable absorbers is helpful to further explore the anomalous dispersion range of ultra-long round-trip pulses and their potential applications.