Confined Terahertz Surface Waves on Meta-Surfaces and Goubau Lines

Integrated circuits revolutionized electronics long time ago and paved the way towards minimized microprocessors today. In analogy, plasmonics aims at the creation of highly integrated optical networks on a small chip that enable the implementation of ultra-small sensors or optical processors. In the terahertz frequency regime, we investigate the propagation of tightly bound pure surface waves on specifically designed meta-surfaces. While most presented meta-surfaces on a thin film in the literature support waveguide mode propagation in the thin film substrate, whose evanescent electromagnetic fields form the surface waves at the waveguide boundaries, we observed pure surface waves that are not coupled to a waveguide mode in the thin film. Such meta-surfaces are particularly advantageous for use as surface sensors, since the surface waves carry most of their energy in the space between the surface and air and almost no energy in the thin film substrate. This is in strict contrast to most of the presented meta-surfaces in literature so far, which guide a significant part of unusable energy in the inaccessible region of the substrate. Furthermore, we study structures of Goubau lines and meta-surfaces that combine excellent spectrally broadband terahertz surface wave guiding with frequency-selective meta-surface areas and meta-surface sub-wavelength resonators on a chip. In detail, we investigate the coupling efficiency between Goubau lines and meta-surfaces.