Real-time comprehensive control over soliton molecules

Soliton molecules, the bound aggregation of sub-solitons, inherently own multi-dimensional properties, thereby manifesting substantial potential in optical communications and optical data storage. However, to release the potential demands the control ability over multi-dimensions of soliton molecules, by which the valid information can be modulated onto these dimensions. Here, we propose a real-time feedback scheme governed by a dedicated-designed two-step optimization algorithm for comprehensively controlling soliton molecular multi-dimensional properties. This technique can manipulate inter-soliton separations and relative intensities of soliton molecules in a basic nonlinear-polarization-evolution-based mode-locked fiber laser. The wide tuning range over the inter-soliton separation from 2 ps to 58 ps is achieved, and seamless tuning with a precision of 0.05 ps is demonstrated. Relative intensities between solitons can also be separately controlled and a two-dimensional joint regulation is performed. Moreover, the real-time transmission over 30-km single-mode fiber is demonstrated and spectral period doubling of soliton molecules is captured, further manifesting the validity of the comprehensive control method.