Reflectance calculations of anisotropic dielectric constants of graphene-like two-dimensional materials

A new optical method for determining anisotropic dielectric constants of graphene-like two-dimensional materials on semiconductor or metal substrates is developed. The method is based on the surface differential reflectance measurements at three different incident angles. The inversion problem is resolved analytically in a long-wavelength approximation, where graphene is discussed within the framework of macroscopic electrodynamics as a uniaxially anisotropic film with the optical axis perpendicular to the film surface. The method is fast and has no need for the initial guesses of the desired parameters. It also offers an effective technique to get good start points for iterative numerical methods to improve the preliminary results. The method is unique in its simplicity and, therefore, important for graphene research.