Hysteresis of a passively mode-locked fiber laser: effects from cavity dispersion

Abstract

Hysteresis is a common phenomenon in passively mode-locked lasers and refers to the effect where the thresholds marking transitions between different pulsation states are not the same for an increasing or decreasing pump power. Despite wide presence in experimental observations, the general dynamics of hysteresis remains elusive, largely due to the challenge to acquire the full hysteresis dynamics of a given mode-locked laser. In this Letter, we overcome this technical bottleneck by fully characterizing an exemplar figure-9 fiber laser cavity, which exhibits well-defined mode-locking patterns in its parameter space or “primitive cell.” We varied the net cavity dispersion and observed the salient change of hysteresis characteristics. Specifically, transiting from an anomalous to a normal cavity dispersion is found to consistently increase the likelihood of the single-pulse mode-locking regime. To the best of our knowledge, this is the first time that a laser’s hysteresis dynamic is fully probed and related to fundamental cavity parameters.

Numerical simulation of two-soliton and three-soliton molecules evolution in passively mode-locked fiber laser

“…2, leading to an increase in cavity losses and a change in pulse width and spectrum. Thirdly, there are multistability and hysteresis phenomena in passively mode-locked fiber lasers [32], [40], [49]. It indicates that the operation of single stability state can be sustained within a certain range of pumping power.…”

“…As the QWP angle changes, the minimum transmission of the curve also changes, and the width and position of the peak of the curve also undergo periodic shifts. It is important to note that not all curves on the profile can support the modelocking, and the mode-locking range varies with pumping power and cavity dispersion [32], [33]. Therefore, viewed along the QWP-angle axis direction, the transmission curves supporting mode-locking overlap and intertwine.…”