Coated Drop-Shaped Nanowires for Guiding THz Surface Plasmon Polaritons with Nanoscale Confinement and Ultra-Long Propagation Distances
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Focusing far beyond the diffraction limit is very important for terahertz (THz) wave applications due to its much longer wavelength compared with optical wave. Surface plasmon polaritons (SPPs) on metal wires are frequently used to attain this focusing. However, when the mode width is reduced down to the nanometer scale, the mode loss is very high. Here, a coated drop-shaped nanowire (CDSN) is proposed for guiding THz SPPs with both ultra-strong mode confinement (10 nm) and extreme-long propagation length (1~15 mm), which result from the distinctive mode fields around the top and bottom arcs, respectively, of the metal wire. The fantastic mode properties make the waveguide very useful in nanophotonics, bio-photonics, and highly integrated photonic circuits.
KeywordsTHz wave Surface plasmon polaritons THz waveguides Metal nanowires
This work was supported in part by the National Natural Science Foundation of China under Grant 61405124, and the Fund Project for Shenzhen Fundamental Research Programme, China under Grant JCYJ20160308092830132.