Tunable repetition-rate all-fiber femtosecond laser delivering 45  fs and 14.4  MW pulses for thermal-damage-free cardiac interventions

High-precision tissue incision in cardiovascular interventions remains hindered by thermal damage and mechanical trauma from conventional tools. Herein, we present a high-peak-power, all-fiber femtosecond laser system integrating gain-managed nonlinear (GMN) amplification and hollow-core photonic bandgap fiber (HC-PBGF) compression. The system delivers direct output pulses with durations of ∼50 fs and peak powers of >10 MW across a repetition rate range of 0.1–5.6 MHz. Notably, at the lowest repetition rate of 0.1 MHz, the system achieves pulse durations as short as 45 fs with a peak power reaching 14.4 MW, representing the highest peak power ever reported for a fully fiber-integrated femtosecond laser architecture. Experimental evaluations via myocardial incision and atrial septal puncture confirmed exceptional tissue-selective incision performance of the system, with no detectable thermal injury or carbonization observed following the procedure. These results overcome critical limitations of existing minimally invasive cardiac instruments, such as collateral thermal effects and inflexible optical configurations. By synergizing GMN spectral control with HC-PBGF dispersion engineering, this compact platform enables sub-100 fs pulse compression within <1 m fibers, resolving key barriers to clinical translation. The technology establishes a transformative pathway for cardiovascular catheter-based interventions, offering unprecedented precision for functional tissue preservation and postoperative recovery.