Physical mechanism of layer-dependent strong and weak coupling with electromagnetic wave in 2H-MoS2

Abstract

In this work, we use the first-principles calculation method to theoretically study the strong and weak coupling between the layer-dependent MoS2 and electromagnetic waves. Through the calculation of the electronic structure and the analysis and fitting of Van Hove singularity (VHS), the differences between the strong coupling and weak coupling mechanisms are discussed. The exponential law of electronic structure parameters with the number of layers is explained. Finally, combined with cavity quantum electrodynamics (QED), it is revealed that the physical mechanism of strong coupling and weak coupling is related to the transition dipole moment. Strong coupling is dominated by inter-band transitions and weak coupling is dominated by in-band transitions.