Low threshold soliton and a noise-like pulse conversion in an all-polarization-maintaining figure-eight cavity

摘要

We experimentally report a lowthreshold soliton and a noise-like mode-locked fiber laser using an all-polarizationmaintaining figure-eight cavity. We built a bidirectional pump structure without a phase shifter at the beginning of the experiment. The resonator has a high mode-locking threshold of 620mW. Afterwards, we used a phase shifter in the resonator, and the laser can self-start in a conventional soliton (CS) mode-locked state when pump1 reaches the threshold of only 70mW. The CS pulse with a duration of 863.8 fs can be observed at 1560 nm. When the two pumppowers increase to 350mWand 50mW, the conventional soliton can convert to noise-like pulses. The central wavelength and pulse duration of noise-like mode-locked pulse are 1560.4 nm and 417.9 fs, respectively. The laser can realize conversion between ultrafast pulses and high-energy pulses, and have a lowthreshold that can be used for nonlinear frequency conversion, supercontinuum generation, sensing, etc. (C) 2021 Optical Society of America