Ultrafast laser pulse bursts, with their unique temporal structure that encapsulates high-repetition-rate subpulses within a low-repetition-rate envelope, are pivotal for advanced applications in micromachining, biological ablation, and imaging. However, achieving simultaneous, independent, and precise control over both the intraburst repetition rate and the total pulse number remains a significant challenge. Here, we propose and experimentally validate a novel paradigm for pulse burst generation based on synergistic intracavity–extracavity control. The core of our scheme is a state-matching mechanism that seamlessly couples the rich, tunable multipulse dynamics of a mode-locked fiber laser with a free-space multicolor pulse multiplication system. This synergy enables flexible and decoupled control over the output burst’s temporal architecture. Experimentally, we demonstrate deterministic generation of multicolor pulse bursts containing up to several tens of pulses, continuous tuning of the intraburst repetition rate, and the generation of high-repetition-rate pulses in the GHz regime from a harmonic mode-locked state. The system also exhibits capabilities for fast binary switching and optical-domain encoding, enabled by programmable control, alongside excellent long-term stability. This highly flexible and scalable source provides a versatile solution for applications demanding complex, tailored ultrafast waveforms.
Zhang et al. (Thu,) studied this question.