Plasmons in graphene on uniaxial substrates

Placing graphene on uniaxial substrates may have interesting application potential for graphene-based photonic and optoelectronic devices. Here we analytically derive the dispersion relation for graphene plasmons on uniaxial substrates and discuss their momentum, propagation length and polarization as a function of frequency, propagation direction and both ordinary and extraordinary dielectric permittivities of the substrate. We find that the plasmons exhibit an anisotropic propagation, yielding radially asymmetric field patterns when a point emitter launches plasmons in the graphene layer.