Flat-top solitons and anomalous interactions in media with even-order dispersions and competing nonlinearities

Flat-top (FT) solitons are optical pulses that arise from the balance of dispersion and self-phase modulation in media with the competing cubic-quintic nonlinearity. Previously, FT solitons were studied only in the case of the second-order dispersion (<i>m</i>=2). Following the recent observation of pure-quartic solitons (corresponding to <i>m</i>=4), we here construct families of FT solitons in the setting with pure-high-even-order dispersion (PHEOD), including <i>m</i>=4,6,8, and 10, and address interactions between them. The PHEOD solitons are completely stable and, unlike the conventional solitons, they feature oscillatory tails. Interactions between the PHEOD solitons are anomalous, featuring repulsion and attraction between in- and out-of-phase solitons, respectively. These results expand the variety of optical solitons maintained by diverse dispersive nonlinear media.