Ultra-Amplification of Surface Plasmon Coupled Emission in Graphene-Silver Hybrid Films

Surface Plasmon Coupled Emission (SPCE) stems from an interaction between fluorophores and thin metallic films and leads to strongly directional $p$-polarized emission with signal intensities that are 10-1000 times greater than isotropic fluorescence emission. Conventional SPCE methods use silver thin films with a SiO$_{2}$ spacer layer to prevent oxidation of silver, and the latter has no role in the signal generation. Here we employ single- and bi- layer graphene (SLG-BLG) as the spacer layer and demonstrate a 10 fold enhancement in comparison to the isotropic fluorescence intensity for rhodamine B fluorophore doped in PVA matrix. A fiber optic spectrometer was used to record the emission which was strongly directional (at 50$^{\circ}$ relative to the incident excitation) and 97{\%} $p$-polarized. Base on our preliminary simulations, we attribute the synergistic interaction between the $\pi $-plasmons of graphene and the surface plasmons of silver as the most important factor in the amplification of the SPCE.