Mode-locked figure-9 fiber laser assisted by a SESAM for improving signal-to-noise ratio and stability

The mode-locked figure-9 fiber laser has been proved to exhibit excellent performance, but improvement of its output signal-to-noise ratio(SNR) and stability are restricted by the laser structure design. In this paper, we propose and verify a modified laser cavity to increase SNR and output stability by introducing a saturable absorber mirror(SESAM) to the single arm end of the figure-9 laser as a mode-locked auxiliary device instead of the typical mirror. Numerical simulations based on the model of the figure-9 fiber and SESAM lasers clearly indicate that modified structure has better output performance than typical one. Additionally, the related experimental results also demonstrate that at the same pump power of 150mW and compare the typical structure, the modified one outputs a higher SNR of 70 dB, together with 12 h output lower RMS of 0.23 %. We believe that the presented laser design could be a stable and reliable ultrafast optical seed for improving the performance of high-power laser facilities, which also has potential applications in optical frequency comb and all-optical modulation.