Dark gap solitons in one-dimensional nonlinear periodic media with fourth-order dispersion

The studies of solitons are usually confined to the models with normal two-order dispersion or diffraction; while recent theoretical predictions and experimental observations have confirmed the important role that the fourth-order dispersion played in, leading to the discovery of a new class of solitons—quartic solitons in fibers. We here theoretically consider the one-dimensional (1D) periodic nonlinear media with both second-order and fourth-order dispersions, and uncover numerically the existence, properties, and stabilities of dark gap solitons populated within the associated linear photonic band gaps. Such gaps, particularly, are affected drastically by normal or anomalous fourth-order dispersion; the dark gap solitons are always found to be unstable for the latter, and are robustly stable and have a wide stability region for the former case, verified by linear-stability analysis and direct perturbed simulations. The obtained results provide insights into physics of dark gap solitons in higher-order dispersion regime.