Intracavity component order controls nonlinear phase accumulation and pulse evolution in erbium-doped fiber lasers

We employed numerical simulations to investigate the influence of the arrangement of the erbium-doped fiber, output coupler, and saturable absorber on pulse evolution in the passively mode-locked erbium-doped fiber laser. The results show that altering the intracavity component order reconstructs the spatial build-up of peak power and the accumulation process of nonlinear phase shifts, resulting in distinct mode-locking build-up dynamics and output characteristics. Among the investigated configurations, structures in which the pulse is first shaped by the saturable absorber and subsequently amplified by the erbium-doped fiber improve gain extraction efficiency and maintain high peak power over longer fiber segments, thereby enhancing the effective accumulation of nonlinear phase shifts. Compared with the other structures, this design exhibits superior performance in terms of pulse compression, peak output power, and time-bandwidth product, while maintaining a stable advantage under different gain conditions.