Sub-20-attosecond timing jitter from a mode-locked 200-MHz All-PM Er:NALM fiber laser

Our research team has achieved a significant milestone by generating pulses with sub-20-attosecond (as) timing jitter from a 200-MHz all-Polarization-Maintaining (PM) erbium-doped (Er:) Nonlinear Amplifying Loop Mirror (NALM) fiber laser. Accurate measurement of these temporal fluctuations was conducted using the Balanced Optical cross-Correlation (BOC) technique. Through comprehensive investigation, we identified the critical parameters responsible for timing jitter, including dispersion and pump power, and validated their impact. The fine-tuning of the contributing factors allowed us to demonstrate an exceptionally low integrated timing jitter of only 15.59 attoseconds, integrated from 10 kHz to 10 MHz. This accomplishment stands as the lowest value ever documented for any free-running mode-locked fiber lasers that are erbium-doped.