Wang X, Wang B, He W, Zhang X, Huang Q, Lin H, Huang Z, Jiang X, Pang M
Opt Express. 2025 Feb 24;33(4):7072-7080. doi: 10.1364/OE.547755.
High-harmonic mode-locking based on strong optoacoustic interactions in solid-core photonic crystal fiber (PCF) has been an established mechanism to achieve a stable GHz repetition rate in a conventional soliton fiber laser, in which a uniform pulse sequence is self-locked to the acoustic core-resonance of the PCF with a specific harmonic order. However, due to the finite bandwidth of the acoustic core-resonance, there may be multiple choices of harmonic order within the resonance bandwidth that could lead to uncertainties in the resultant harmonic order. In this work, we report observations of dynamic self-adaptation of the pulses in the laser cavity towards a stable harmonic order when the cavity is initially set at a neighboring less stable harmonic order. We observed that self-adaptation can occur spontaneously towards either higher or lower harmonic order depending on the initial condition. We observed rich dynamics during the self-adaptation process namely transient pulse sliding, random pulse collisions, and pulse drop-outs. This work provides experimental insight into the robustness of the self-locked repetition rate in optoacoustic mode-locking, and we believe will be useful in understanding and controlling harmonically mode-locked lasers.
基于实心光子晶体光纤（PCF）中强烈的光声相互作用的高谐波锁模，已成为在传统孤子光纤激光器中实现稳定GHz重复频率的既定机制，在这种激光器中，均匀脉冲序列会以特定谐波阶数自锁到PCF的声学芯共振上。然而，由于声学芯共振的带宽有限，在共振带宽内可能存在多个谐波阶数的选择，这可能导致最终谐波阶数存在不确定性。在这项工作中，我们报告了当初始将激光腔设置在相邻的较不稳定谐波阶数时，腔内脉冲朝着稳定谐波阶数的动态自适应观测结果。我们观察到，根据初始条件，自适应可以自发地朝着更高或更低的谐波阶数发生。我们在自适应过程中观察到了丰富的动力学现象，即瞬态脉冲滑动、随机脉冲碰撞和脉冲丢失。这项工作为光声锁模中自锁重复频率的鲁棒性提供了实验见解，我们相信这将有助于理解和控制谐波锁模激光器。
