Effect of applied uniform strain on the plasmon modes in graphene double-layer structures

In this work, charge density excitations in uniformly strained double-layer graphene structures are carried out up to first order in the strain tensor. Taking the reported low energy Dirac Hamiltonian for the anisotropic Fermi velocity tensor, plasmon properties may be described by linear response theory and the relationship between the density response function and induced current density under a weak external applied field. We show that plasmon energies of the optical and acoustic modes of the graphene double-layers depend substantially on their optical anisotropic tensor conductivity, the strain modulus and the direction of the applied tension. Also, we determine that plasmon excitation is based on the observation of a deep sharp minimum in the reflection coefficient of the suggested anisotropic graphene structure upon the incident angle and strain in the Kretchmann configuration. Because strain induces anisotropy in graphene optical conductivity, the strain-dependent orientation plays an important role to manipulate the variations of the graphene plasmon energy, which may be useful to tune graphene properties in plasmonic devices to enhance light-matter interaction.