Breathing pulses, as a unique nonlinear pulse phenomenon, play a key role in optimizing laser performance, nonlinear optical processes, and complex signal transmission. Unlike stable solitons, the breathing pulses fluctuates in energy periodically with time, and both pulse frequency and amplitude exhibit periodic changes. Through appropriate nonlinear effects, lasers can generate stable breathing pulses, achieving a mode-locked state that exhibits a periodic “breathing” pattern. Based on this, a fiber laser combining a saturable absorber as the mode-locking element is designed and built, and stable breathing states are successfully observed at lower pump power levels. High-speed detection techniques and time-stretched dispersive Fourier transform (TS-DFT) technology are used to time-amplify and spectrally analyze the rapid pulses, while monitoring the evolution of the breathing pulse in both time domain and frequency domain. Experimental results indicate that the change in pump power significantly affects the periodic modulation induced by additional oscillations, thereby controlling the breathing ratio and ultimately resulting in the formation of a stable soliton. When the pump power is between 470 and 480 mW, the formation of the breathing pulse is first observed, with a breathing ratio of up to 4.5. As the pump power increases, the breathing effect gradually diminishes, and at 510 mW, it completely disappears, with the breathing ratio dropping to 1.These results confirm the critical role of pump power in controlling the breathing pulse state and its transition, demonstrating the potential of controlling pump power in ultrafast laser technology and nonlinear optics. The breathing pulse phenomenon, as a periodic pulse behavior, reflects the complex dynamical characteristics between nonlinear optical effects and cavity parameters. Combined with the natural synchronization system formed between the breathing frequency and the cavity frequency (determined by the cavity length), the periodic change of the breathing pulse becomes a crucial factor for controlling laser output. By adjusting parameters such as the laser’s nonlinearity and dissipation, the characteristics of the breathing pulse and breathing ratio can be precisely controlled, thus achieving precise control of the laser output. The periodic oscillatory characteristics of the breathing pulse inside the laser cavity lead to the non-uniform distribution of pulses, a feature that demonstrates enormous potential in pulse shaping, ultrashort pulse generation, and precise frequency comb control. Additionally, the presence of the breathing pulse may affect the stability and energy conversion efficiency of the laser, providing new perspectives for designing and optimizing lasers.
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