Controlled manipulation of solitons in a recirculating fiber loop using external potentials

TL;DR

This work addresses real-time control of optical solitons in non-dissipative systems by introducing a programmable external-potential platform implemented via synchronous phase modulation in a recirculating fiber loop. A mean-field model resembling a 1D Gross-Pitaevskii equation with a distributed potential $V(x,t)$ is derived, alongside a Hamiltonian particle description for soliton interactions, which is validated against experiments. The authors demonstrate single-soliton trapping, parametric excitation, and precise two-soliton dynamics, with quantitative agreement between the experimental trajectories and Hamiltonian predictions. The approach offers a versatile toolkit for engineered nonlinear wave dynamics, enabling inverse-scattering-transform spectrum shaping, exploration of soliton gases, and generalized hydrodynamics in photonic systems.

Abstract

Optical solitons are self-sustained wave packets that propagate without distortion due to a balance between dispersion and nonlinearity. Their unique stability underpins key photonic applications while also playing a central role in nonlinear wave physics. However, real-time control over soliton dynamics in non-dissipative systems remains a major challenge, limiting their practical applications in photonic systems. Here, we introduce a fiber-based platform for soliton manipulation, by creating programmable external potentials through synchronous arbitrary phase modulation in a recirculating optical fiber loop. We demonstrate precise soliton trapping, parametric excitation, and coupled multi-soliton interactions, revealing particle-like behavior in excellent agreement with a Hamiltonian description in which solitons are treated as interacting classical particles. The strong analogy with matter-wave solitons in Bose-Einstein condensates highlights the broader implications of our approach, which provides a versatile experimental tool for the study of nonlinear wave dynamics and engineered soliton manipulation.

Figures (11)

• Figure 1: Experimental setup. (a) Principle of operation of the synchronously phase modulated recirculating fiber loop. Example of experimentally recorded spatiotemporal dynamics of a single soliton in the case of (b) no external potential and (c) trapping within a truncated parabolic potential (used for describing the setup in (a)). Typical peak power and duration of the solitons are $\sim 30mW$ and $\sim 45ps$ FWHM.
• Figure 2: Dynamics of a single soliton in a trapping potential taking consecutively three different shapes. (a) Space-time dynamics of a single soliton subjected to the potential trap. Zooms highlighting (d) sinusoidal oscillations, (c) total temporal reflections and (b) succession of temporal reflections and parabolic trajectories. Dashed lines in (b-d) are the trajectories estimated by the particle model shifted by $-80ps$ for clarity. (e-g) Shapes of the phase modulations applied in each segment obtained from heterodyne measurement (see Supplement for details regarding the measurement method). Solid lines are the averaged profiles and colored areas show the standard deviation of the phase measurement.
• Figure 3: Manipulation of solitons using spatiotemporally varying harmonic potentials. (a) Soliton in a slowly modulated trap and (b) driven at the parametric resonance. The red dashed lines denote the boundaries of the truncated parabolic traps. Outside of the region enclosed by these lines the external potential is flat. The blue lines in (b) indicate the exponential growth of the amplitude of the oscillations predicted by the particle model. (c) Evolution of the instantaneous period of oscillation of the soliton in (a) compared to the prediction of Eq. (\ref{['eq:period']}) considering an adiabatic evolution. (d) Sketch of the truncated parabolic phase modulation.
• Figure 4: Coherent dynamics of soliton pairs. (a) Schematic view of the initial condition of the experiments: one soliton is initially centered in the quadratic trap while the other is detuned. (b-d) Spatiotemporal dynamics recorded for three increasing coupling strengths: $\Delta Z/ \ Z_0 = -1.6\%$, $-6.9\%$, $-11.2\%$ respectively. Dashed blue and orange lines denote the amplitude of oscillation of each soliton. (b2) and (d2) Same as (b) and (d) rotated by 90°. Simulated particle trajectories obtained from Eq. (\ref{['eq:H']}) are superimposed as dashed and dotted lines.
• Figure 5: Regular and chaotic dynamics of soliton triplets. Spatiotemporal dynamics of a (a) regular and (c) chaotic soliton triplet. The green horizontal line in (a) shows the range of distance over which velocities of the solitons are initiated. Dashed vertical lines indicate the boundaries of the truncated parabolic trap. (b, d) Respective intensity profiles recorded at $z = 500km$ in blue. Solid red lines and shaded areas illustrate the trapping potential applied after 500km while the dashed green line in (b) indicates the phase modulation applied for $500km \leq z \leq 585km$ to initiate velocities of the solitons.