Modeling electromagnetic interactions of molecules in nanophotonic materials

PhD ceremony: Mr. C.A. Marocico, 12.45 uur, Academiegebouw, Broerstraat 5, Groningen

Dissertation: Modeling electromagnetic interactions of molecules in nanophotonic materials

Promotor(s): prof. J. Knoester

Faculty: Mathematics and Natural Sciences

The research presented in this thesis focuses on the numerical modeling the electromagnetic interactions of molecules placed in close proximity to nanoscale objects, e.g. nanorods, photonic crystals, etc. The presence of such objects dramatically changes the emission and energy transfer rates of molecules, with important applications for light-emitting diode (LEDs), microscopy, solar cells, micro- and nano- lasers, etc.

We have considered several geometries, such as metallic waveguides, dielectric and metallic cylinders and photonic crystals. For each geometry we have calculated numerically the emission rate of a molecule and the energy transfer rate between two molecules. In the case of metallic waveguides and cylinders we have found that both the emission and the energy transfer rates can be increased by several orders of magnitude when compared to empty space. This large enhancement is due to the excitation of surface plasmons that provide additional channels that can efficiently transport the energy of an excited molecule, either away from the system or to a neighboring molecule. When considering a photonic crystal, the addition of a metallic substrate affords a good control of the emission and energy transfer rates throughout the band-gap that characterizes photonic crystals.

The results obtained provide a deeper understanding of the electromagnetic properties of molecules and can be used to optimize the design of devices used for lighting (LEDs), energy harvesting (solar cells) and other applications.