Thesis of Alexandre Lebel

Defense of thesis d'Alexandre Lebel - laboratory PhLAM

Abstract :

The work presented in this thesis is dedicated to the study of modulational instability in optical fibers.
Light propagation in optical fibers, governed by the nonlinear Schrödinger equation, presents a very rich and complex dynamic. However, this equation belongs to the so-called integrable equations. This means that there is a mathematical method (Inverse Scattering Transform) comparable to a nonlinear Fourier transform allowing an exact resolution. However, access to the electric field (phase and intensity) makes it difficult to use it with experimental datas.
A time-lens system has been previously developed within the team, allowing simultaneous recording of the phase and the intensity of the electric field (SEAHORSE). In the work that we present here, we have improved this device, in particular by eliminating the majority of chromatic aberrations from the measurement system. By doing so we obtain sufficient resolution to measure the complex field generated by the process of modulational instability. We were then able to apply the Inverse Scattering Transform to compare our experimental measurements of the stimulated and spontaneous cases with our numerical simulations as well as different theoretical results in this space.

Keywords : Ultrafast measurement,Nonlinear optics,Soliton,Integrable turbulence,Modulational instability