  Transmission through a subwavelength terahertz fiber, which is positioned in
parallel to a frequency selective surface, is studied using several finite
element tools. Both the band diagram technique and the port-based scattering
matrix technique are used to explain the nature of various resonances in the
fiber transmission spectrum. First, we observe that spectral positions of most
of the transmission peaks in the port-based simulation can be related to the
positions of Van Hove singularities in the band diagram of a corresponding
infinite periodic system. Moreover, spectral shape of most of the features in
the fiber transmission spectrum can be explained by superposition of several
Fano-type resonances. We also show that center frequencies and bandwidths of
these resonances and, as a consequence, spectral shape of the resulting
transmission features can be tuned by varying the fiber-metamaterial
separation.
