Study of Positive and Negative Refraction of Visible Light at the Cu/Air Interface

Abstract

Light transmission at the Cu/air interface was measured in the visible region for a series of wedge-shaped Cu film samples. It is found that light refraction at the Cu/air interface changes from negative in the Drude region, passing through zero at about E g , to positive in the interband-transition region. Detailed discussion is given to exclude those mechanisms which have been arguably assigned as the cause of negative refraction at a metal/dielectric interface. Based on the spectra of the measured refractive index and modeled in the Drude region, the positive and negative refraction analyzed in this work are qualitatively in agreement with dispersion of the group refractive index, and may aid in understanding light transmission at the metal/dielectric interface as characterized by the law of refraction.