Engineering dimensionality of resonant many-body dipole-dipole interactions using a nanophotonic environment.*

Resonant dipole-dipole interactions (RDDI) govern phenomena such as Van der Waals forces, Casimir-Polder forces, and Forster resonant energy transfer. In the limit of many dipoles, it is known that the fluorescent decay profile of donor molecules changes from a single-exponential to a stretched-exponential decay trace due to resonant dipole-dipole interactions with acceptor molecules. While the stretched exponential profile, I(t) = I₀exp(-γ₀t-αt^1/2), is well-known to 3D geometries, the fluorescence decay dynamics in more complicated nanophotonic environments remain largely unexplored. To this end, we present a systematic study of the fluorescent decay profile of donor (Alq3) and acceptor (R6G) molecules spin-coated on a plasmonic metasurface consisting of 2D silver nanoparticle lattice. We observe modified fluorescence decay traces on the plasmonic meta-surface compared to conventional control samples such as glass or silver substrates. Our work sheds light on the origin of fluorescent decay dynamics and shows that they provide a way of uncovering the dimensionality of dipole-dipole interactions modified by a nanophotonic environment.