Goos–Hänchen shift for Gaussian beams impinging on monolayer-MoS2-coated surfaces

Abstract

We report a detailed theoretical study of the Goos–Hanchen (GH) shift for a fundamental Gaussian beam on the surface coated with monolayer (ML) molybdenum disulfide (MoS2), a promising two-dimensional transition metal dichalcogenide (2D-TMDC) and a direct band-gap semiconductor. A general model has been developed to predict the GH shifts on ML-MoS2-coated surfaces for a light beam with different wavelengths. In contrast to the conventional GH shift, which is generally observed for total internal reflection, here we predict finite spatial and angular GH shift for both partial and total internal reflection conditions. Our analysis revealed that the observation of the giant negative spatial GH shift on MoS2-coated surfaces is attributed to the surface conductivity of the MoS2 ML, something that has never been explored. Furthermore, we find that the GH shifts are dependent on the mode of polarization, the wavelength of incident beam, and the nature of surfaces. This deepens our understanding of the unusual behavior of GH shift near Brewster’s angle as well as the critical angle of incidence. We expect that our findings will lead to several new applications of MoS2 in sensors and device technology.