Abstract-Routing of strongly confined terahertz spoof surface plasmon polaritons on metasurfaces along straight and curved pathways with subwavelength width

Sven Becker, Tassilo Fip, and Marco Rahm

Field maps of the 𝑧$z$-component of the SSPP electric field 𝐸𝑧$E_z$ in the 𝑥$x$-𝑦$y$-plane at 𝑧$z$ = 50µm away from the metasurface. The close-ups indicate the geometric relation between the SSPP electric field distribution and the subjacent metasurface structure. The SSPP electric field is monitored at frequencies of (a) 0.48 THz for the straight 1-cut-wire metasurface, (b) 0.34 THz for the 2-cut-wire metasurface and (c) 0.28 THz for the 3-cut-wire metasurface. (d) Absolute value of 𝐸𝑧$Ez$ along an intersection line in 𝑦$y$-direction at 𝑥=$x=$ 1000 µm transverse to the propagation direction of the SSPPs for (1) the 1-cut-wire, (2) the 2-cut-wire and (3) the 3-cut-wire metasurface.

https://www.osapublishing.org/oe/abstract.cfm?uri=oe-28-5-6766

In search of new technologies for optimizing the performance and space requirements of electronic and optical micro-circuits, the concept of spoof surface plasmon polaritons (SSPPs) has come to the fore of research in recent years. Due to the ability of SSPPs to confine and guide the energy of electromagnetic waves in a subwavelength space below the diffraction limit, SSPPs deliver all the tools to implement integrated circuits with a high integration rate. However, in order to guide SSPPs in the terahertz frequency range, it is necessary to carefully design metasurfaces that allow one to manipulate the spatio-temporal and spectral properties of the SSPPs at will. Here, we propose a specifically designed cut-wire metasurface that sustains strongly confined SSPP modes at terahertz frequencies. As we show by numerical simulations and also prove in experimental measurements, the proposed metasurface can tightly guide SSPPs on straight and curved pathways while maintaining their subwavelength field confinement perpendicular to the surface. Furthermore, we investigate the dependence of the spatio-temporal and spectral properties of the SSPP modes on the width of the metasurface lanes that can be composed of one, two or three cut-wires in the transverse direction. Our investigations deliver new insights into downsizing effects of guiding structures for SSPPs.

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