Frequency-dependent fundamental and dipole gap solitons in PT -symmetric nonlinear metamaterials

We derive a theoretical model with frequency-dependent parameters for describing the transmission of electromagnetic waves in PT-symmetric metamaterials (MMs). Based on the derived theoretical model, we investigate the tunable band structure and eigenvalue problem in the negative or positive index region of MMs, and predict the existence and stability of fundamental, out-of-phase, and in-phase dipole gap solitons in defocusing or focusing nonlinear PT-symmetric MMs. Furthermore, we discuss the enhanced localization of solitons under different formation conditions. The results reveal that there exist abundant gap solitons with frequency controllability in PT-symmetric MMs, and the established theoretical model paves the way to explore more solitons in PT-symmetric MMs.