Collective Dynamics of GHz Dissipative Solitons

Soliton molecular complexes – a collective pattern of solitons – feature fruitful nonlinear dynamics in dissipative optical systems, making them a significant concept from an interdisciplinary standpoint. Recently, a new type of collective pattern termed quasi-single soliton has been identified as a constituent of the soliton crystal, significantly contributing to the low-threshold mode-locking of GHz soliton lasers. Owing to its underlying complex interactions underpinned by multi-scale gain, the GHz soliton laser serves as an excellent platform for investigating the collective dynamics of dissipative solitons, a field that remains largely unexplored. To this end, a theoretical framework based on twofold gain effects is developed to predict the collective dynamics of soliton decay and reboot (SDR) and irregular Q-switched instability. In the experimental validations, a gated temporal-spectral measurement system utilizing a single parametric time-lens is developed. The measurements in real time conform well with the numerical predictions of the GHz fiber laser. Additionally, the intermittent dynamics, manifested as the SDR process during the quasi-steady state's intermediate phase, uncovers its underlying connection with the multi-scale gain landscapes. These efforts can shed new light on the dynamic-gain-driven collective dynamics of GHz dissipative solitons.