Far-field modulation of fluorescence decay rates in pairs of oriented semiconducting polymer nanostructures

We report on the observation of far-field dipole-dipole coupling in pairs of uniformly $z$-oriented polymer nanostructures manifested as a fluorescence lifetime modification (both enhancement and suppression relative to isolated particles) modulated by interparticle separation. The observed oscillatory modulation in the fluorescence decay rate as a function of interparticle distance (ranging from $200$ to $\approx 2000\mathrm{nm}$) results from modification of the vacuum field at the position of the probe dipole by the presence of the second radiating dipole. These results provide observation of a dipole-dipole interaction in the “inductance” interparticle distance scale between the near field $(\approx 200\mathrm{nm})$ and far field $(>500\mathrm{nm})$, important for the realization of efficient active nanophotonic devices.