Application of a Differential Polarization Interferometer for Measuring of the Optical Path Length in Thin Metamaterial Layers with Reflection and Absorption Losses

A differential polarization interferometer capable of correctly measuring the optical path length in thin metamaterial layers with absorption and reflection losses has been developed. As a result of direct measurement, it is shown that an Ag(28 nm)/SiO2(12 nm) binary layer deposited on a glass substrate is characterized by a negative refractive index in a wide range of incident angles of a laser beam with a wavelength of 632.8 nm.