Controlling the fluorescence resonant energy transfer by photonic crystal band gap engineering

The fluorescence of dye molecules embedded in a photonic crystal is known to be inhibited by the presence of a pseudo-gap acting in their emission range. Here we present the first account of the influence that an incomplete photonic band gap or pseudo-gap has on the fluorescence emission and fluorescence resonant energy transfer. By inserting synthetic, donor (D)-acceptor (A)-labeled oligonucleotide structures in self-organized colloidal photonic crystals, we were able to measure simultaneously the emission spectra and lifetimes of both donor and acceptor. Our results clearly show an inhibition of the donor emission together with an enhancement of the acceptor emission spectra, indicating improved energy transfer from donor to acceptor. These results are mainly attributed to a decrease of the number of available photonic modes for radiative decay of the donor in a photonic crystal in comparison to that of the effective homogeneous medium. The fluorescence decay parameters are also dominated by the pseudo-gap acting on the energy-transfer efficiency.