Light-matter interaction between templated molecular layers and surface lattice resonances

We couple an aligned layer of merocyanine molecules with surface lattice resonances in a plasmonic grating. The alignment of the molecular layer is achieved using a layer of aligned graphene nanoribbons as a template, resulting in anisotropic optical properties. The anisotropy manifests itself in polarization-dependent coupling between excitons in the organic layer and lattice plasmons in the grating. We study the influence of the templating on the coupling and find that, surprisingly, the more orientationally ordered templated layer displays a lower coupling strength than an identical amorphous merocyanine layer. Simulations show that the polarization of incident light is partly converted to the orthogonal component with respect to the incident direction, and this may affect the light-matter coupling strength. Our work demonstrates the use of molecular templating in controlling the interaction of excitons with excitations in optical nanostructures and the critical role of the polarization of light in this.