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Low-loss forward and backward surface plasmons in a semiconductor nanowire coated by helical graphene strips
Journal of the Optical Society of America B, #35(8), pp.2066?2074 (2018)

V.I. Shcherbinin, V.I. Fesenko and V.R. Tuz

In the long-wavelength approximation, an effective conductivity tensor is introduced for graphene ribbons (strips) placed periodically at the interface between two media. The resulting conducting surface is considered as a coating for semiconductor nanowire. For the hybrid waves of such nanowire, the dispersion equations are obtained in explicit form. Two types of surface plasmons are found to exist: (i) modified surface plasmons, which originate from the ordinary surface plasmons of a graphene-coated semiconductor nanowire, and (ii) spoof plasmons, which arise on the array of graphene ribbons and may possess forward-wave and backward-wave dispersion. It is revealed that the spoof surface plasmons are low-loss ones, and their frequencies, field confinement, and group velocities can be tuned widely by adjusting the coil angle and width of the helical graphene strips.