Radiating multimode dispersive shock waves

Area of Science:

• Nonlinear optics
• Fiber optics

Background:

• Dispersive shock waves (DSWs) are nonlinear phenomena typically studied in single-mode fibers.
• Geometric parametric instability can compete with DSW formation in multimode fibers.
• Understanding spectral reshaping in the normal dispersion regime is crucial for pulse propagation studies.

Purpose of the Study:

• To predict the observation of DSWs in multimode fibers with a parabolic index profile.
• To investigate the role of spatial self-imaging in DSW radiation.
• To develop a model for understanding spectral reshaping in the normal dispersion regime.

Main Methods:

• Numerical simulations using a full 1 + 3D model.
• Development of a reduced model to derive a phase-matching rule.
• Analysis of wave propagation in multimode fibers with a parabolic index profile.

Main Results:

• DSWs can be observed in multimode fibers despite competing geometric parametric instability.
• Spatial self-imaging induces DSW radiation at multiple resonant frequencies.
• A simple phase-matching rule accurately describes resonances, matching full model predictions.

Conclusions:

• The study confirms DSWs in multimode parabolic fibers.
• Spatial self-imaging is key to understanding multi-resonant frequency radiation.
• The findings provide insights into spectral reshaping of intense pulses in normal dispersion.