  A new approach for the spatial and temporal modulation of electromagnetic
fields at terahertz frequencies is presented. The waveguiding elements are
based on plasmonic and metamaterial notions and consist of an
easy-to-manufacture periodic chain of metallic box-shaped elements protruding
out of a metallic surface. It is shown that the dispersion relation of the
corresponding electromagnetic modes is rather insensitive to the waveguide
width, preserving tight confinement and reasonable absorption loss even when
the waveguide transverse dimensions are well in the subwavelength regime. This
property enables the simple implementation of key devices, such as tapers and
power dividers. Additionally, directional couplers, waveguide bends, and ring
resonators are characterized, demonstrating the flexibility of the proposed
concept and the prospects for terahertz applications requiring high integration
density.
