Ultrashort pulse propagation and conical emission in multimode optical fibers

Abstract

Nonlinear light propagation in multimode fibers has recently attracted a surge of interest through the investigation of complex linear and nonlinear modal interactions provided by the added spatial degrees of freedom when compared to single-mode waveguides. In that respect, recent observations include ultra-broadband spectral broadening (i.e., supercontinuum generation) and frequency conversion processes, as well as nonlinear beam cleaning, to name a few. The motivation of mentioned works is usually two-fold. First, for a deeper understanding of nonlinear optics, and second to address the great expectations concerning the application of multimode fibers for high-capacity communication networks and for high-energy fiber lasers. However, most of the time, the derived numerical models only support qualitatively experimental results, in particular, when the number of modes involved becomes significant (i.e., higher than 10) and ultra-broadband frequency conversion processes (i.e., more than one octave) also occur. There is an urgent need of clarifying the potential and areas of applicability of numerical models to facilitate the accurate design of future nonlinear and multimode fiber devices.