We report fabrication method and THz characterization of composite films
containing either aligned metallic (tin alloy) microwires or chalcogenide
As2Se3 microwires. The microwire arrays are made by stack-and-draw fiber
fabrication technique using multi-step co-drawing of low-melting-temperature
metals or semiconductor glasses together with polymers. Fibers are then stacked
together and pressed into composite films. Transmission through metamaterial
films is studied in the whole THz range (0.1-20 THz) using a combination of
FTIR and TDS. Metal containing metamaterials are found to have strong
polarizing properties, while semiconductor containing materials are
polarization independent and could have a designable high refractive index.
Using the transfer matrix theory, we show how to retrieve the complex
polarization dependent refractive index of the composite films. We then detail
the selfconsistent algorithm for retrieving the optical properties of the metal
alloy used in the fabrication of the metamaterial layers by using an effective
medium approximation. Finally, we study challenges in fabrication of
metamaterials with sub-micrometer metallic wires by repeated stack-and-draw
process by comparing samples made using 2, 3 and 4 consecutive drawings. When
using metallic alloys we observe phase separation effects and nano-grids
formation on small metallic wires
