Mode characteristics of a D-shaped porous fiber with a thin gold layer in the THz regime

In this work, we carry out theoretically the mode analysis of a D-shaped porous fiber with a thin gold layer in the THz spectral range. From a proper design of the gold layer, effective losses can be reduced and a zero waveguide dispersion is achieved as the result of the coupling between the fiber modes and surface plasmons. We argue that the reached guidance features can be used to implement in the THz spectrum an analog version of SPR (surface plasmon resonance) D-type optical fibers.