Optical turbulence and spectral condensate in long fibre lasers

Abstract

We study numerically optical turbulence using the particular example of a recently created, ultra-long fibre laser. For normal fibre dispersion, we observed an intermediate state with an extremely narrow spectrum (condensate), which experiences instability and a sharp transition to a fluctuating regime with a wider spectrum. We demonstrate that the number of modes has an impact on the condensate's lifetime. The smaller the number of modes, the more resistant is the condensate to perturbations. Experimental results show a good agreement with numerical simulations.

Quantum Gibbs distribution from dynamical thermalization in classical nonlinear lattices

“…At present the nonlinear dynamics of modes in laser fiber arrays attracts significant interest from the optics community (see e.g. [50][51][52]). We take here a relative large value of a static field f = 1 having in mind to model the evolution of the nonlinear Schrödinger equation in a Sinai billiard.…”

“…like in [32,47]), nonlinear photonic lattices (e.g. like in [30,31]) or optical fiber arrays [50][51][52] which seems to us to be especially promising.…”

Wave condensation with weak disorder versus beam self-cleaning in multimode fibers

“…We recall that this self-organization process takes place in a conservative (Hamiltonian) and formally reversible system: The ('condensate') remains immersed in a sea of small-scale fluctuations ('uncondensed particles'), which store the information for time reversal. In this respect, wave condensation is of different nature than other forms of condensation processes discussed in optical cavity systems, which are inherently nonequilibrium forced-dissipative systems [20,[28][29][30][31][32][33][34][35][36].…”

Incoherent Shock and Collapse Singularities in Non-Instantaneous Nonlinear Media

“…The derivation of a more complete hydrodynamic-like model describing the regularization of the shock-collapse singularity is a difficult task related to a long-standing mathematical problem, namely achieving a closure of the infinite hierarchy of equations that govern the evolutions of ω-moments in transport kinetic equations [44,45]. It is important to note in this respect that the wave-turbulence closure is usually justified in the weakly non-linear regime [46][47][48][49] leading to the celebrated (Boltzmann-like) kinetic equation for optical waves [28], which describes important phenomena such as light thermalization [50][51][52][53][54][55], wave condensation [28], or the dynamics of certain fiber lasers [56][57][58][59]. On the other hand, the closure of moments equations considered here concerns the opposite strongly non-linear regime.…”