Special Session 188: Dynamics of interacting optical solitons

Nonlinear synchronisation and routes to complexity in breathing-soliton lasers

Sonia Boscolo VPIphotonics GmbH & Aston Institute of Photonic Technologies Germany Co-Author(s):    Junsong Peng, Xiuqi Wu, Huiyu Kang, Anran Zhou, Ying Zhang, Heping Zeng, Christophe Finot

Abstract: We present an overview of our recent research demonstrating ultrafast fibre lasers operating in the breathing-soliton regime--dynamic pulses exhibiting periodic energy oscillations--as a powerful and versatile platform for investigating nonlinear synchronisation dynamics within a single oscillator. In these systems, synchronisation emerges intrinsically from nonlinear coupling between internal cavity frequencies, enabling self-synchronisation without external forcing. Leveraging advanced diagnostics and control strategies, we uncover a rich spectrum of dynamical behaviours, including higher-order Farey hierarchies of frequency-locked breather states, self-similar fractal structures (devil`s staircases), abnormal synchronisation domains characterised by unconventional Arnold tongues, transitions between synchronised and desynchronised regimes--including a previously unknown intermediate dynamical state--and a new route to chaos arising from the breakdown of regular dynamics. A unified theoretical model, revealing distinct breather formation mechanisms under net-normal and near-zero cavity dispersion, explains the different experimental behaviours observed in these regimes in terms of pump-power accessibility relative to stationary mode locking, oscillation periods, spectral features, and synchronisation capabilities. Together, these findings advance the understanding of nonlinear dynamical systems and provide a novel experimental framework for probing and controlling complex dynamical regimes.

Laser soliton interactions through optoacoustic effects in photonic crystal fibers

Wenbin He Shanghai Institute of Optics and Fine Mechanics, CAS Peoples Rep of China Co-Author(s):    Wenbin He, Meng Pang, Xin Jiang, and Philip St.J. Russell

Abstract: Solid-core photonic crystal fibers (PCF) can greatly enhance optoacoustic effects due to the tight confinement of both optical and acoustic modes. By leveraging the enhanced optoacoustic nonlinearity in a PCF in a mode-locked fiber laser, we have achieved the self-organization of a large number of laser solitons through long-range optoacoustic interactions mediated by coherently stimulated acoustic resonance, resulting in a highly ordered soliton sequence with prominent self-stability and flexibility. We investigated the self-organization dynamics of multi-soliton structures through a hierarchical study and simulated the process using a highly effective low-dimensional model based on coarsely grained dynamics. In addition to enabling a self-stabilizing, pattern-editable pulsed laser with a GHz repetition rate, this unique long-range interaction has also facilitated the generation of a new type of complex multi-scale soliton sequences, known as soliton supramolecules, through cooperative balancing with other interaction mechanisms. We have also realized a ``parallel optical-soliton reactor'' via controllable soliton interactions within a massive number of parallel temporal trapping potentials based on the optoacoustic effects, enabling statistical studies of laser soliton interactions.

Dissipative patterns, solitons and bullets under radiative effects, higher dimensions, and topology. Bifurcations and dynamics overview.

Carles Milian Enrique Universitat Politecnica de Valencia Spain Co-Author(s):    Carlos Mas, Salim Ivars, Pol Molina, Yaroslav Kartashov

Abstract: Recent progress on the effects of higher dimensions, Raman scattering, and Cherenkov analogue radiation emitted by dissipative solitons in driven micro-cavity is presented, together and separately. Novel insights in the context of normal vs anomalous dispersion regimes are presented. We report on one-dimensional radiating solitons of the bright and dark natures in the anomalous and normal cavity dispersion regimes, aiming at elucidating certain previously seemingly unexplored connections amongst them. Additionally, we show that in higher dimensions, new types of nonlinear states appear under the action of a spatially localised driving fields. These include localised patterns and solitons of the quiescent and moving types. To finalise, we briefly show robust topological light-bullets in large area fiber loops co-living with the higher order and typically detrimental effects.

Localized patterns and slanted snaking in bichromatically driven pure Kerr optical cavities

Pedro Parra-Rivas Universidad de Almeria Spain Co-Author(s):    E. K. Akakpo, Y. Sun, M. Erkintalo, F. Leo, and P. Parra-Rivas

Abstract: We investigate the bifurcation structure and stability of localized temporal patterns in bichromatically driven pure Kerr optical cavities. In contrast to the common case, where localized states are supported by a uniform background state, here localization occurs within a modulated background. By performing bifurcation analysis, we unveil the origin of such states and find that they undergo a slanted snake-and-ladder structure. These states endure oscillatory instabilities which lead to breathers: oscillatory localized patterns. In the presence of desynchronization between the envelope formed from the superposition of the driving fields and an integer fraction of the cavity round trip time, these states are asymmetric, stable, and drift at a constant speed. As a result, the slanted snaking breaks, leading to the formation of isolas. We find that, eventually, by increasing that parameter, these localized patterns disappear.

Two-photon dual-comb imaging of soliton dynamics

Lukasz A Sterczewski Wroclaw Univeristy of Science and Technology Poland Co-Author(s):

Abstract: Optical solitary waves (solitons) arise from the balance between dispersion and nonlinear effects at high optical intensities in laser cavities. Interestingly, solitons can form transient or stable pulse aggregates referred to as soliton molecules. Although these structures show promise for applications in quantum memory and advanced telecommunications, they present challenges in laser development. Emission involving multiple pulses affects nonlinear frequency conversion and generates pronounced amounts noise. Moreover, detecting these formations is difficult with standard methods such as intensity autocorrelation or spectral analysis due to instrumental constraints, so they often go overlooked. In this talk, we will discuss a practical method for fast, real-time diagnostics of pulsed lasers based on two-photon absorption in a nonlinear photodetector. This approach allows the observation of soliton molecules with separations ranging from femtoseconds to nanoseconds, across any wavelength and timescale, using a standard telecom laser oscillator and a low-bandwidth oscilloscope. We will demonstrate how this technique can be used to monitor basic soliton molecules, such as triplets and quadruplets, as well as more intricate structures like molecular crystals and soliton rains. We will also cover the use of shared-cavity dual-comb lasers for studies on soliton-soliton interactions.

Pathway-Resolved Noise Channels in Temporal Cavity Solitons

Yifan Sun Universite libre de Bruxelles Belgium Co-Author(s):

Abstract: Fluctuations of nonlinear coherent structures arise not only from direct stochastic forcing, but also from deterministic transfer among coupled collective coordinates. In this talk, I present a framework for resolving such noise pathways in a stable temporal cavity soliton governed by the generalized Lugiato-Lefever equation with Raman response. By projecting both the field dynamics and the vacuum noise onto four soliton coordinates: amplitude, frequency shift, temporal position, and global phase, we derive a reduced stochastic model whose linearization yields an analytic power-spectral-density matrix. This formulation separates direct noise injection from inter-coordinate transfer and thereby exposes the internal routing of fluctuations. It captures frequency-to-timing conversion associated with Gordon-Haus-type jitter, identifies amplitude-to-phase coupling as a major source of phase noise, and reveals Raman-enabled cascaded transfer pathways. It also explains the low-detuning enhancement of intensity and phase noise through an underdamped amplitude-phase relaxation mode that emerges before the onset of breathing. Comparisons with stochastic simulations of both the reduced model and the full equation show good agreement across most of the stable stationary regime.

Stairway to soliton in the down conversion regime

Francesco Rinaldo Talenti University of Bath England Co-Author(s):

Abstract: Although a solitary wave is conventionally defined as being driven by third-order nonlinearities, recent theories and experiments have proposed novel approaches that extend functionalities and applications by exploiting other nonlinear terms. In particular, the generation of harmonics via x(2) effects underpins two-color soliton generation. The physics increases in complexity and interest, as a plethora of novel stable solutions can be generated. Specifically, we show how a staircase of Eckhaus instabilities directly links the homogeneous steady state to the half-harmonic soliton in the down-converted regime. Interestingly, we found that the conversion between harmonics also facilitates dark soliton excitation at the driven wavelength, a phenomenon that is typically difficult to achieve in standard systems.