Experimental characterization of optical nonlocality in metal-dielectric multilayer metamaterials

The optical nonlocality in metal-dielectric multilayer metamaterials is characterized experimentally as a function of the angle of incidence with respect to the TE-polarized incident light. The physical mechanism of the difference between the nonlocal effective permittivity and the effective-medium-theory-based effective permittivity depending on the incident angle is theoretically revealed through the analysis of the band structure, the dispersion relation, and the iso-frequency contours according to the transfer-matrix method. Such effective permittivity difference is also retrieved in the metal-dielectric multilayers based on the measured transmission and reflection spectra.