Terahertz surface plasmon waveguide based on a one-dimensional array of silicon pillars

Abstract

We experimentally demonstrate a three-dimensional plasmonic terahertz waveguide by lithographically patterning an array of sub-wavelength pillars on a silicon substrate. Doped silicon can exhibit conductive properties at terahertz frequencies, making it a convenient substitute for conventional metals in plasmonic devices. However, the surface wave solution at a doped silicon surface is usually poorly confined and lossy. Here we demonstrate that by patterning the silicon surface with an array of sub-wavelength pillars, the resulting structure can support a terahertz surface mode that is tightly confined in both transverse directions. Further, we observe that the resonant behavior associated with the surface modes depends on the dimensions of the pillars, and can be tailored through control of the structural parameters. We experimentally fabricated devices with different geometries, and characterized the performance using terahertz time-domain spectroscopy. The resulting waveguide characteristics are confirmed using finite element numerical simulations, and we further show that a simple one-dimensional analytical theory adequately predicts the observed dispersion relation.

Spoof plasmons in corrugated semiconductors

“…It is interesting to notice that heavily doped silicon (n > 2.2 × 10 19 cm −3 ) has been shown to exhibit metallic properties at terahertz frequencies [39,40] and has the potential to replace metals in such applications. [41] In order to consistently assess the effect of loss on the waves with the Drude permittivity, it is suggested firstly to review the major features of the waves in respective lossless case.…”

Strong coupling of diffraction coupled plasmons and optical waveguide modes in gold stripe-dielectric nanostructures at telecom wavelengths

“…15 and experimentally confirmed for terahertz surface plasmon waveguides in ref. 16. We have investigated the diffraction coupled plasmon resonances in pure gold NSs with fixed stripe wide 400 nm and height in the range from 60 to 90 nm with step of 10 nm.…”

Regenerated amplification of terahertz spoof surface plasmon radiation

“…In recent years, the THz VEDs based on the spoof surface plasmon (SSP) becomes promising due to the intriguing characteristics of SSP, such as the local resonant effect, strong near-field confinement. Thus it brings new possibilities of realizing better performance and higher operation frequency than the traditional slow-wave interaction systems [14][15][16][17][18][19].…”