Decoupled polarization dynamics of incoherent waves and bimodal spectral incoherent solitons

Abstract

We consider the propagation of strongly incoherent waves in optical fibers in the framework of the vector nonlinear Schrödinger equation (VNLSE) accounting for the Raman effect. On the basis of the wave turbulence theory, we derive a kinetic equation that greatly simplifies the VNLSE and provides deep physical insight into incoherent wave dynamics. When applied to the study of polarization effects, the theory unexpectedly reveals that the linear polarization components of the incoherent wave evolve independently from each other, even in the presence of weak fiber birefringence. When applied to light propagation in bimodal fibers, the theory reveals that the incoherent modal components can be strongly coupled. After a complex transient, the modal components self-organize into a vector spectral incoherent soliton: The two solitons self-trap and propagate with a common velocity in frequency space.

Weak Langmuir turbulence in disordered multimode optical fibers

“…As a general rule, the multimode turbulent system exhibits a self-organization process, in which all modes self-consistently form a vector spectral incoherent soliton (VSIS). This provides a generalization of the scalar (or bimodal) spectral incoherent solitons that were previously investigated by always ignoring the structural disorder of the fiber [6,41,[48][49][50]. The reported VSIS can also exhibit a discrete behavior, which is characterized by collective synchronized spectral oscillations of the discrete soliton in frequency space.…”

Multimode Nonlinear Fiber Optics: Massively Parallel Numerical Solver, Tutorial, and Outlook

“…Raman scattering underlies multimode spectral incoherent solitons [75]. It can cause energy transfer between modes, which occurs for example in Raman beam cleanup [76].…”

Multimode Nonlinear Fiber Optics: Massively Parallel Numerical Solver, Tutorial and Outlook

“…Raman scattering is a dissipative process where a phonon from the fiber medium interacts with the electric field, causing a spectral redshift that is either continuous (in the case of solitons and multimode solitons [24], [74]) or discrete (more typical in the normal dispersion regime [19], [41], but also observed for group-velocity matched modes with anomalous dispersion [55], [71]). Raman scattering underlies multimode spectral incoherent solitons [75]. It can cause energy transfer between modes, which occurs for example in Raman beam cleanup [76].…”