General theory and observation of Cherenkov radiation induced by multimode solitons

Advancements in computational capabilities along with the possibility of accessing high power levels have stimulated a reconsideration of multimode fibers. Multimode fibers are nowadays intensely pursued in terms of addressing longstanding issues related to information bandwidth and implementing new classes of high-power laser sources. In addition, the multifaceted nature of this platform, arising from the complexity associated with hundreds and thousands of interacting modes, has provided a fertile ground for observing novel physical effects. However, this same complexity has introduced a formidable challenge in understanding these newly emerging physical phenomena. Here, we provide a comprehensive theory capable of explaining the distinct Cherenkov radiation lines produced during multimode soliton fission events taking place in nonlinear multimode optical fibers. Our analysis reveals that this broadband dispersive wave emission is a direct byproduct of the nonlinear merging of the constituent modes comprising the resulting multimode soliton entities, and is possible in both the normal and anomalous dispersive regions. These theoretical predictions are experimentally and numerically corroborated in both parabolic and step-index multimode silica waveguides. Effects arising from different soliton modal compositions can also be accounted for, using this model. At a more fundamental level, our results are expected to further facilitate our understanding of the underlying physics associated with these complex many-body nonlinear processes. The multifaceted nature of nonlinear multimode optical fibers has provided a fertile ground for observing novel physical effects otherwise impossible in single-mode setting. The authors present a theoretical and experimental study, providing a comprehensive theory capable of explaining the distinct nature of wideband Cherenkov radiation produced during multimode soliton fission events.

Automated summary

Advancements in computational capabilities and accessing high power levels have led to a reevaluation of multimode fibers, which are now being pursued to address information bandwidth issues and implement new high-power laser sources. The complexity of interacting modes in multimode fibers has provided fertile ground for observing novel physical effects, but also presents challenges in understanding emerging physical phenomena. A comprehensive theory has been developed to explain the distinct Cherenkov radiation produced during multimode soliton fission events, enhancing understanding of the complex nonlinear processes. The multifaceted nature of nonlinear multimode fibers allows for the observation of unique physical effects, not possible in single-mode settings.