Effect of Thin Metallic Layers on the Refractive Index of a Multilayer System

We present a simplified structure made of periodic metallic layers on a glass substrate, which offers a potentially simpler approach to building photonic crystals. Using microwave experiments and Fresnel formulas, we investigate the refractive index properties of these structures. We make both transmission and reflection measurements and find that the refractive index of a periodic layered media decreases depending on the periodicity of the geometric arrangement, dielectric contrast and filling fraction of metallic layers. It is shown that metallic layers lead to a substantial change of interference pattern which can be interpreted as a result of interference in a uniform medium with a refractive index smaller than 1.