Spoof terahertz surface plasmon polaritons on metasurface pathways and networks

In the last decades, highly integrated electronic circuits have paved the way towards compact, smart electronic devices with excellent computing power. Considering the benefits of electronic integration, it is compelling to apply similar integration methods to shrink the size of photonic on-chip devices in the terahertz and optical regime. Here, we numerically and experimentally investigate the guiding, routing and manipulation of strongly confined spoof terahertz surface plasmon polaritons (terahertz SSPPs) on metasurface pathways. The pathways are composed of single-, two- or three-cut wires that define the subwavelength width with respect to the SSPP wavelength. We measured the spatio- and spectro-temporal dynamics of the electric field of the SSPPs by electro-optic imaging. We observed that the terahertz SSPPs exhibit a strong out-of-plane and in-plane confinement, even when they propagate on curves of subwavelength path width. The spatio- and spectro-temporal behavior of the terahertz SSPPs evidences that they can be tightly guided within subwavelength space on metasurfaces without loss of the out-of-plane confinement. Due to these beneficial electromagnetic properties, metasurface pathways of subwavelength width seem to be ideally suited for the implementation of on-chip terahertz networks and sensor systems.