Flexible Quasi-Three-Dimensional Terahertz Metamaterials
  We characterize planar electric terahertz metamaterials fabricated on thin, flexible substrates using terahertz time-domain spectroscopy. Quasi-three-dimensional metamaterials are formed by stacking multiple metamaterial layers. Transmission measurements reveal resonant band-stop behavior that becomes stronger with an increasing number of layers. Extracted metamaterial dielectric functions are shown to be independent of the number of layers, validating the effective medium approximation. Limitations of this approximation are discussed. 
Abul K. Azad, Hou-Tong Chen, Antoinette J. Taylor, Elshan Akhadov,   Nina R. Weisse-Bernstein, and John F. O'Hara (Los Alamo...