Highly-Multimode Solitons in Step-Index Optical Fiber

We report the generation of multimode solitons in step-index fiber. The solitons are superpositions of 5-10 temporally-aligned transverse modes, they exhibit speckled beam profiles, and the spatio-spectral variation across the soliton can be complex. Greater understanding of multimode solitons should create a foundation for further research into complex multimode nonlinear phenomena in step-index fibers. With energies of tens of nanojoules and durations around 100 fs, the multimode solitons are speckled fields with peak powers that can exceeed 300 kW, parameters which may be valuable in applications.