Theoretical Investigation of Resonance Energy Transfer Using Discrete and Continuous Donor and Acceptor Models

Resonance energy transfer (RET) is the transport of electronic energy from an excited atom or molecule to another. Besides being an essential process in photosynthesis, RET presents useful applications such as spectroscopic nanoruler and photosensitization of semiconductors. In this study, we investigate the ways to harness high RET rates using various models. First, we consider systems that consist of a single donor-acceptor pair and a metal nanoparticle (NP) to identify the geometrical factors that maximize RET rates when the donor-acceptor pair is coupled to the plasmon-enhanced near-field. It is demonstrated that conversely, rate information can be used to obtain geometrical information of nanophotonic systems. Then, it is shown that RET involving multiple donors may invoke collective mechanisms that give rise to higher RET efficiency, exemplified by activation of surface lattice resonance (SLR) modes and energy transfer among the donors. Finally, energy transfer from a medium consisting of donors as a four-level system to a medium of acceptors as a two-level system is described by solving integral equations involving polarization and electric field.