Proceedings of SPIE, the International Society for Optical Engineering/Proceedings of SPIE

Tuning of spontaneous emission in photonic crystals by resonant energy transfer and magnetic fields

Wim Libaers, Kris Baert, Renaud A. L. Vallée, Branko Kolarić, Koen Clays

Published Apr 23, 2008• 0 citations

Abstract

The fluorescence of emitters embedded in a photonic crystal is known to be inhibited by the presence of a photonic pseudo-gap acting in their emission range. Here we present a comparative study of the influence of the pseudo-gap on the fluorescence emission of either organic dyes or nanocrystals embedded within a photonic crystal. Our results clearly show that the optical properties of the emitters are primarily controlled by the presence of a pseudo-gap which causes inhibition of the emission in both cases, regardless of the differences in chemical composition. These findings are mainly attributed to a decrease of the number of available photonic modes for radiative decay of the emitter in a photonic crystal compared to the effective homogeneous medium. Furthermore, we show that a photonic crystal can be used to control the fluorescence energy transfer (FRET) between donor-acceptor (D-A) pairs of dyes. Finally, we show that the application of an external magnetic field can finely tune the emission characteristics of emitters with a permanent magnetic moment.

DOI: 10.1117/12.780261

Related papers

Energy transfer between fluorescent dyes in photonic crystals

Zhengwen Yang, Xinran Zhou, Xueguang Huang +5 more

Energy transfer from fluorescein (Fl) to Rhodamine B (RhB) in the opal photonic crystals has been investigated by photoluminescence. The results show that the energy transfer can be enhanced effectively by photonic bandgaps. When the fluorescence emission wavelength of donor Fl overlaps the photonic bandgap the fluorescence intensity of the donor is suppressed, while the fluorescence intensity of acceptor RhB is obviously enhanced. This enhancement can be attributed to the inhibition of radiative emission of the donor in the photonic crystals.

Optics LettersAug 20, 200826 citations

Spontaneous-emission rates of quantum dots and dyes controlled with photonic crystals

Willem L. Vos

Chapter 1 IntroductionUltimate inhibition of spontaneous emission can be achieved in artificial periodic structures with tailor-made forbidden frequency bands [5].These periodic structures known as photonic crystals consist of different dielectric materials, where the index of refraction varies on length scales comparable to the wavelength of light.Therefore, the periodicity of photonic crystals is about 1000 times as large as that of atomic crystals.Light with specific frequencies is forbidden to propagate along certain directions by wave interference, similarly to Bragg diffraction of x-rays in atomic crystals.Such forbidden frequency ranges are called stopgaps.The larger the contrast of the refractive index between the two materials of a photonic crystal, the more strongly light is influenced, and the broader the stopgaps become.It was predicted in 1987 that an extreme situation may be feasible when light cannot propagate along any direction [6, 7].This situation is called a photonic bandgap.Spontaneous emission is completely inhibited for frequencies inside such a bandgap and, conversely, strongly enhanced for frequencies outside the bandgap.Photonic crystals, therefore, provide an ultimate tool for manipulating with light, which is of extreme interest for scientists and engineers [8, 9].Recent advances in nanotechnology have resulted in ability to synthesize semiconductor structures with dimensions of a few nanometers.Due to the finite sizes, electron-hole pairs (excitons) can be confined in these nanostructures, which leads to discrete excitonic energy levels.The nanocrystals that confine excitons in spherical or circular spaces are known as quantum dots.The discrete structure of the energy levels results in advantageous optical properties of these nanocrystals: narrow and tunable emission spectra.The emission frequencies can be tuned by varying the nanocrystal size: the smaller the size, the higher the emission frequency.These properties make the nanocrystals very promising elementary emitters for new experiments and devices [10, 11]. Outline of the thesisThis thesis describes time-and angle-resolved experiments, in which effects of threedimensional (3D) photonic crystals on spontaneous emission of embedded light sources (quantum dots and dye molecules) were studied.The thesis is organized as follows:In Chapter 2 we review the theoretical basics of the interaction between light and matter.We discuss the factors triggering the process of spontaneous emission and consider in detail the time evolution of the excited state of the emitter that interacts with the quantized 1.

Nov 2, 20064 citations

Spontaneous Emission of Organic Molecules Embedded in a Photonic Crystal

Eugene P. Petrov, V. N. Bogomolov, I. I. Kalosha +1 more

We report on modification of the spontaneous emission of dye molecules embedded in a three-dimensional solid-state photonic crystal exhibiting a stop band in the visible range. Molecules embedded in artificial opal filled with a polymer show a dip in the fluorescence spectrum and nonexponential spontaneous decay kinetics containing both accelerated and inhibited components compared to the dye fluorescence in a reference polymer matrix. Results are interpreted in terms of redistribution of the photon density of states in the photonic crystal.

Physical Review LettersJul 6, 1998297 citations

Nonexponential decay of spontaneous emission from an ensemble of molecules in photonic crystals

Renaud A. L. Vallée, Kris Baert, Branko Kolarić +2 more

Photonic crystals (PCs) with relatively low dielectric contrast (i.e., with pseudogaps) have significant influence on the fluorescence decay of internal emitters. Fluorescence decays of ensembles of dye molecules measured at different positions in the PCs exhibit a nonexponential behavior, which is best fitted by a continuous distribution of decay rates. The most frequent decay rates of these distributions are smaller and their widths are narrower in a PC with a pseudogap acting in the emission range of the emitters than in a PC having the pseudogap out of this range. These experimental results have been well accounted for by calculations of the local density of states and rate constant for spontaneous emission.

Physical Review BJul 19, 200743 citations

Modeling Spontaneous Emission Control in Photonic Crystals by Ferromagnetic Resonance

U. Hoeppe, Christian Wolff, H. Benner +1 more

The radiation dynamics of a magnetic dipole located inside a photonic crystal has been considered as an analogue for optical emission of a point-like emitter in such a crystal. We have experimentally realized this situation by fixing a single crystal yttrium iron garnet (YIG) sphere of 1.7 mm diameter inside a photonic crystal consisting of dielectric alumina rods. These rods form a woodpile structure of size 16 × 6 × 6 cm3 . The photonic crystal shows a band gap at microwave frequencies between 12.9 and 14.3 GHz as calculated and verified from the transmission characteristics of the crystal. The radiation feedback of the YIG sphere was probed by ferromagnetic resonance experiments covering a large frequency range from 8 to 17 GHz. Whereas outside the band gap the radiation-induced linewidth amounts up to 30 Oe, it is almost completely suppressed inside the gap. From the full analysis of linewidth and resonance shift, we could clearly prove the non-Markovian character of the radiation dynamics at the edges of the gap as expected from theory. The experimental control of spontaneous emission, as realized in our experiment, is a very promising step towards future optical applications in low threshold lasers, highly efficient light emitting diodes or photovoltaic solar modules.

IEEE Transactions on MagneticsFeb 20, 20132 citations

Emission amplification by enhanced energy transfer using a photonic crystal

Luis González-Urbina, Javier Moreno, Koen Clays

The efficiency of emitter sensitizers in OLEDs and solar cells can benefit from the properties of a photonic crystal. The reduction of energy modes by the photonic band gap favours Förster energy transfer in donor-acceptor pairs, and results in a population increase on the emitter excited states. Here we show how the intensity from Ir(ppy)3, typically used as an emitter and as a sensitizer, can be enhanced in the presence of BAlq under the influence of a photonic band gap. The suppression of the radiative emission from the BAlq due to optical confinement in a 3-dimensional photonic crystal helps to populate the excited states of the Ir(ppy)3 which leads to a high increase on the emission from this molecule. Since these organometallic compounds are extensively used in current technologies, the effect can have impact on many organic systems used in OLEDs and solar cells

Sep 14, 20110 citations