Fig. 3
From: Accelerated nonlinear interactions in graded-index multimode fibers
Spectral evolution in a tapered multimode fiber as obtained from a generalized Unidirectional Pulse Propagation Equation simulation. A 400-fs, 1550 nm pulse with a peak power of ~50 kW is injected in a 40 cm long tapered multimode fiber, whose core radius decreases from 40 to 10 µm. After only a few centimeters of propagation, the input pulse undergoes a soliton fission and a sequence of dispersive waves emerges in the visible. Upon further propagation, the generated multimode solitons experience fission-like processes (red horizontal lines) that almost immediately expand the spectrum and generate new blue-drifted dispersive wave lines
