Heidelberg 2015 – wissenschaftliches Programm
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Q: Fachverband Quantenoptik und Photonik
Q 66: Photonics I
Q 66.1: Gruppenbericht
Freitag, 27. März 2015, 11:00–11:30, B/gHS
Upconversion in photonic environments — •Jan Christoph Goldschmidt1, Clarissa Hofmann1, Stefan Fischer2, and Barbara Herter1 — 1Fraunhofer Institut für Solare Energiesysteme, Freiburg, Deutschland — 2University of California Berkeley, Berkeley, USA
Upconversion is the creation of one high-energy photon out of at least two lower energy photons. Upconversion of low-energy photons from a non-coherent radiation like sunligth is most frequently a multi-step process: ground state absorption is followed by energy transfer between two excited upconverter species, excitation of higher states and spontaneous emission of a high-energy photon. Such upconversion is observed in lanthanide-based upconverters or by triplet-triplet annihilation in organic materials. Solar-energy harvesting and bio-imaging are potential application of upconversion. We present how the upconversion dynamics can be controlled by a photonic environment in a congruent theoretical and experimental analysis. The theoretical model describes the local change of the irradiance and the modification of the local density of photon states induced by the photonic environment. These modifications are then considered in a rate-equation model of the upconversion dynamics. We performed measurements of the upconversion luminescence for two different photonic environments: a resonant cavity and a grating structure. The good agreement found between the experimentally observed enhancement of UC luminescence and the model predictions confirms the developed theoretical method.