Stable harmonic mode locking in soliton fiber laser with frequency shift : Theory and experiment

Abstract

Laser sources delivering high-repetition-rate ultrashort pulses are highly demanded in numerous photonic applications. Among them, harmonically mode-locked soliton fiber lasers exhibiting advantageous consumer properties, such as compactness, reliability, low cost and maintaining convenient output are mostly demanded. Drawback of these lasers is relatively large timing jitter which is significantly higher than the timing jitter in lasers operating at fundamental frequency. We report the stabilizing frequency shift effect in harmonic mode-locking ring soliton fiber laser that is studied theoretically and numerically. It is known that a harmonic mode-locking regime in a fiber laser occurs due to interpulse repulsion, which leads to a uniform distribution of pulses in the cavity. We demonstrate that the frequency shift contributes to an increase in the hardness of interpulse interactions and can led to stabilization of the periodic arrangement of pulses. The experiment carried out confirms the theoretical predictions and the results of numerical simulation.