A deep subwavelength terahertz plasmonic waveguide based on graphene-metal hybrid structure is proposed. A broadband mode confinement down to 1/100 of the free-space wavelength λ0 with a loss of 0.6 dB/λ0 can be achieved when the intra-band electron relaxation time is 100 ps. We show that very narrow slits with an appropriate periodicity created in the metal layer can serve as a grating to efficiently excite the surface plasmon-polariton mode with a normally incident terahertz beam, which can be further exploited for investigation of both interesting physics and innovative applications.
The surface polar optical phonon scattering of carriers in graphene on various substrates is thoroughly studied using Rode's iteration method. The dependence of the scattering rate on carrier energy, temperature, and Fermi energy is investigated. The experimental data in the literature on the temperature dependence of the resistivity can be fitted using only one free fitting parameter. The fitting results show that the coupling strengths of surface optical phonons are much stronger, by at least a factor of 3.5, than the theoretical prediction. The strong coupling also suggests that the deformation potential of acoustic phonons might have been overestimated in the literature.
Abstract:The terahertz plasmon dispersion of a multilayer system consisting of graphene on dielectric and/or plasma thin layers is systematically investigated. We show that graphene plasmons can couple with other quasiparticles such as phonons and plasmons of the substrate; the characteristics of the plasmon dispersion of graphene are dramatically modified by the presence of the coupling effect. The resultant plasmon dispersion of the multilayer system is a strong function of the physical parameters of the spacer and the substrate, signifying the importance of the substrate selection in constructing graphene-based plasmonic devices.
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