MUCCI Alexandre : Optical Soliton Gas

Résumé de thèse :

In nonlinear physics, the fundamental soliton [1] has attracted considerable interest because of its crucial role in the dynamics, primarily because of its main property: the ability to maintain its shape throughout its evolution and its resilience when interacting with other nonlinear waves.

When dealing with the propagation of light through single-mode optical fibers, the one-dimensional nonlinear Schrödinger equation (1D-NLSE) is commonly employed. This equation gives rise to distinctive solutions known as bound states of solitons, which manifest when two or more fundamental solitons coexist within the same spatial domain without any relative velocity. Our research focuses on the spatio-temporal dynamics associated with localized phase modulation within these bound states of solitons. Particularly, we demonstrate our ability to manipulate the velocity of these solitons. Furthermore, we compare our results with an Inverse Scattering Transform (IST) spectrum perturbation theory, a technique analogous to the classical Fourier transform but tailored for nonlinear integrable equations in which the signal is decomposed into its solitonic components characterized by their amplitudes and velocities [2].

In our experiment, we generate a square-shaped light pulse comprising a few solitons and launch it into a Recirculating Optical Fiber Loop system [3] that enables us to capture the spatio-temporal dynamics in single shot. Additionally, we use homodyne interferometric methods to measure the phase, enabling full characterisation of the initial complex field.

Finally, we show the spatio-temporal dynamics in both unperturbed and perturbed scenarios. Our experimental results exhibit a good quantitative agreement with the predictions of the IST perturbation theory. These results are robust in the presence of perturbative higher-order effects such as dissipation that breaks the integrability.

[1] A Shabat, V Zakharov Sov. Phys. JETP, 34, 62 (1972)
[2] VI Karpman, EM Maslov Zh. Eksp. Teor. Fiz, 73, 537-559 (1977) [3] AE. Kraych et al, Phys. Rev. Lett., 122, 054101 (2019)

Doctorant : MUCCI Alexandre

Directeur(s) de thèse : Francois COPIE, Pierre SURET