Light gap bullets in defocusing media with optical lattices

One-Dimensional Gap Soliton Molecules and Clusters in Optical Lattice-Trapped Coherently Atomic Ensembles via Electromagnetically Induced Transparency

“…In periodic potentials, by tuning the strength, periodicity, and structure of the periodic structures, one can obtain controllable finite forbidden gaps of the underlying linear Bloch-wave spectrum, and particularly, as far as optics are concerned, the light waves with frequencies lying within such finite gaps are not allowed to be propagated due to the strong Bragg scattering, while those waves with frequencies lying inside the linear Bloch bands (but not the finite gaps) can be freely propagated as a carrier of both energy and information, enabling the versatile applications in modern optics communications. Diverse localized modes (no matter the matter waves or classical waves), including fundamental solitons, gap solitons, and vortices, have been found with the help of periodic potentials and under nonlinear regimes [19][20][21][22][23][24][25][26][27][28][29][30][31][32][33]; the latter two modes combine the finite gap's strong localization and materials's nonlinearity, enabling the formation and control of robust localized gap modes. Recently, the localization of light and matters has been extended to a novel twisted structure named Moiré superlattices that can be tuned to periodic form under the Pythagorean angle and an aperiodic one for other angles [34][35][36][37][38][39][40][41]; particularly, soliton formation and gap solitons and vortical ones have been addressed in such settings [28,[39][40][41][42][43].…”