Intermodal dispersive wave generation and soliton linear-wave interaction in optical fibers

The emission of dispersive wave and soliton linear-wave interaction are two of the widely studied nonlinear phenomena in fiber optics. They manifest as the generation of a new spectral component when a strong ultrashort optical pulse with/without a weak linear-wave propagates along an optical fiber in the presence of higher-order dispersions. Recent works have demonstrated that the dispersive wave generation and soliton linear-wave interaction can be interpreted in the spectral domain through the cascade of four-wave mixing processes. We show in this work that the emission of the dispersive wave is a special case of soliton linear-wave interactions, in which the linear-wave is degenerate from the soliton field. By studying the driving field (soliton) and linear-wave in different modes, the role of the soliton is to provide cross-phase modulation to the linear-wave as in the earlier studies, while the fiber dispersion is to detrimentally shape the pure cross-phase modulated linear-wave spectra into the seemingly 'idler component'. We present a theoretical model to approximately calculate the spectral profile of the generated idler/dispersive wave and further verify our model with numerical simulations.