Abstract
Metamaterials with large-scale freestanding Ag-SU-8-Ag sandwich configuration, perforated with a square periodic array of circular holes, are fabricated. The transmittance spectra of both experiment and simulation have shown the existence of two transmittance peaks in the middle-infrared region. Numerical simulations based on the effective media method and the effective parameter retrieval procedure verify that the low-frequency transmittance peak results from the electric and the magnetic resonance associated with the negative refractive index. The influence of dielectric loss of the interlayer on transmission and negative refractive response is discussed. Numerical simulations indicate that the transmission within the negative refractive index region decreases, while the dielectric loss of interlayer increase, mainly due to the enhanced reflection. Moreover, the electric resonance mode further increases the absorption resulted from the dielectric loss of interlayer.