In this work, we theoretically investigated the excitation of surface plasmon-polaritons (SPPs) in deformed graphene by attenuated total reflection method. We considered the Otto geometry for SPPs excitation in graphene layer under external strain. We calculated the light reflectance from the structure, which allows concluding what part of the energy of the incident wave has passed into the excitation of SPPs.During the work, we investigated plasmonics of deformed graphene lattice, as illustrated in Fig. 1. The optical conductivity tensor for this modified graphene lattice has non-zero off-diagonal components [1] σxy = σyx = 2σ0(ω)βsx/a and modified diagonal components σxx, yy = σ0(ω)[1 ± 2βsx/a], where σ0(ω) is graphene conductivity, β the electron Gruneisen parameter, sx and sy are the components of relative displacement of graphene sub-lattice s. A possible scenario for such deformation could occur in graphene grown on a substrate with an appropriate combination of lattice mismatch between the two crystals [2, 3].
Calculations show that elastic strain leads to significant effect in SPPs excitation (see Fig. 2). We have considered graphene lattice with the relative displacements s = (0.04, 0.03). In the deformed graphene, excitation of SPPs may be observed for narrower frequency region than in the isotropic graphene. The frequency and the incident angle of the most effective excitation of SPPs strongly depend on the polarization of the incident light. Our results may open up new possibilities for strain-induced molding flow of light at nanoscales.
[1] M. Oliva-Leyva, G.G. Naumis, Phys. Rev. B 93, 035439 (2016).
[2] G.-X. Ni et al., Adv. Mater. 26, 1081 (2014).
[3] S.-M. Lee et al., Nano Res. 8, 2082 (2015).
Photonic & plasmonic nanomaterials , Optics and transport on 2D materials
