Negative refraction in molybdenum disulfide.

Recently, negative refractions have been demonstrated in uniaxial crystals with no necessary of negative permittivity and permeability. However, the small anisotropy parameterγin the uniaxial crystals limits the negative refraction occurrence only in a small range of the incident light angle, retarding its practical applications. In this paper, we report negative refraction induced by a pronounced anisotropic behavior in the bulk MoS2. Using the first-principles, the dielectric function and refractive index calculations confirm a uniaxial trait of MoS2 with a calculated anisotropy parameterγlarger than 2.5 in the entire range of visible wavelength. The critical incident angle to trigger a negative refraction in the bulk MoS2 is calculated up to 90°. The finite-difference time-domain simulations prove that the incident light with a density of 59.5% can be negatively refracted in a MoS2 slab with a thickness of 0.1 µm. Our results open up a new pathway for MoS2-like materials to a novel field of optical integration.