Optimized Noise and Stability Regimes in XPM-Suppressed All-PM Linear Mode-Locked Fiber Lasers

We demonstrate that suppression of intra-cavity cross-phase modulation (XPM) significantly improves the stability and noise performance of all-PM linear mode-locked fiber oscillators. Comprehensive numerical simulations show that XPM suppression dramatically expands the oscillator's stability range by reducing roundtrip nonlinear phase-noise accumulation and intensity fluctuations. For experimental confirmation, a modified oscillator with switchable XPM suppression is constructed, enabling direct comparative measurements in both soliton and stretched-pulse regimes. In agreement with the numerical results, XPM suppression is found to enable a substantial reduction in relative intensity noise (RIN) and timing jitter, with integrated RIN decreasing from 0.08% to 0.06% and jitter improving from 87 fs to 39 fs (9 kHz - 5 MHz) in the soliton regime. In the stretched-pulse regime, RIN drops from 0.07% to 0.04%, and jitter is reduced from 22 fs to 14.5 fs (3 kHz - 5 MHz). These results advance XPM-suppressed all-PM linear mode-locked fiber lasers toward precision applications in frequency metrology, optical synchronization, and biomedical imaging.