Localized gap modes of coherently trapped atoms in an optical lattice

We theoretically investigate one-dimensional localized gap modes in a coherent atomic gas where an optical lattice is formed by a pair of counterpropagating far-detuned Stark laser fields. The atomic ensembles under study emerge as Lambda-type three-level configuration accompanying the effect of electromagnetically induced transparency (EIT). Based on Maxwell-Bloch equations and the multiple scales method, we derive a nonlinear equation governing the spatial-temporal evolution of the probe-field envelope. We then uncover the formation and properties of optical localized gap modes of two kinds, such as the fundamental gap solitons and dipole gap modes. Furthermore, we confirm the (in)stability regions of both localized gap modes in the respective band-gap spectrum with systematic numerical simulations relying on linear-stability analysis and direct perturbed propagation. The predicted results may enrich the nonlinear horizon to the realm of coherent atomic gases and open up a new door for optical communication and information processing. (C) 2021 Optical Society of America under the terms of the OSA Open Access Publishing Agreement

Automated summary

Localized gap modes in one-dimensional coherent atomic gases were theoretically investigated using Lambda-type three-level configuration and the multiple scales method. Fundamental gap solitons and dipole gap modes were discovered, and their (in)stability regions in the band-gap spectrum were confirmed through systematic numerical simulations. These predicted results may expand the nonlinear horizon in coherent atomic gases and provide new opportunities for optical communication and information processing.