Nonlinearity optimization of dispersion-managed mode-locked Yb-doped fiber lasers with near-zero net cavity dispersion

Femtosecond laser pulses are widely used in many fields due to their narrow pulse width and high peak power. The dispersion-managed fiber mode-locked laser has higher pulse energy, wider spectrum and narrower pulse due to its unique in-cavity breathing mechanism. The fiber mode-locked laser using chirped Bragg grating for dispersion management can realize the real all-fiber structure and improve the compactness and stability of the laser. Therefore, the fiber mode-locked laser using chirped Bragg grating for dispersion management has more practical significance. The effects of different distribution of single-mode fiber in ytterbium-doped fiber mode-locked laser based on chirped fiber Bragg grating on pulse dynamics and output pulse parameters are studied by numerical simulation. The influence of the distribution of single-mode fiber on the dynamic process of pulse in the cavity is analyzed when the net dispersion is different. The simulation results show that when the net cavity dispersion is negative, the shorter the single-mode fiber between the chirped fiber Bragg grating and the gain fiber, the higher the pumping threshold and the wider the output spectrum of the fiber laser can maintain the stable monopulsing operation, so that the narrow pulse width can be obtained. When the net cavity dispersion is close to zero, the effect of the length of single mode fiber between the chirped fiber Bragg grating and the gain fiber on the output pulse parameters is more significant. When the net cavity dispersion is positive, the influence of the single mode fiber distribution in the cavity on the output pulse gradually weakens, and the performance of the mode-locked laser is not significantly improved by optimizing the single-mode fiber distribution. Finally, an optimization method is proposed to improve the output performance of the laser by changing the distribution of single mode fiber in the cavity.