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COLLOIDAL PHOTONIC CRYSTALS AND

SUPERLATTICES FOR PHOTONIC APPLICATIONS

WP6 NANOPHOTONICS, Koen Clays

Overview:• Introduction to Photonic Crystals and colloidal PC’s• Photonic heterostructures: BANDGAP ENGINEERING• Fluorescence inhibition (steady-state) and

non-exponential decay (time-resolved)Spectral narrowing of fluorescence(for LASING)Improved Fluorescence Resonance Energy-

Transfer (FRET) in photonic crystals (for LIGHT HARVESTING)

• Magnetic effects in quantum dots vs. closed shell• New avenues: inverted opals, hollow spheres, titania spheres,

vortex pinning, ...

colloidal photonic crystals by convective self-assembly

Well-ordered arrays of colloidsRefractive index changes periodicallyPhotonic band structure arises

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wavelength (nm)J. Chem. Phys. 118(23), 10752 (2003)

SANS data over an area of 0.7 cm2 from a photonic crystal composed of 270 nm silica spheres depositedby convective self-assembly.

photograph of optical diffraction pattern for different laser wavelengths and schematic theoretical pattern:

Overview:• Introduction to Photonic Crystals and colloidal PC’s

• Photonic heterostructures: BANDGAP ENGINEERING

• Fluorescence inhibition (steady-state) and non-exponential decay (time-resolved)

Spectral narrowing of fluorescence(for LASING)Improved Fluorescence Resonance Energy-

Transfer (FRET) in photonic crystals (for LIGHT HARVESTING)

• Magnetic effects in quantum dots vs. closed shell• New avenues: inverted opals, hollow spheres, titania spheres, vortex

pinning, ...

Introduction of functionality: Langmuir – Blodgett Monolayers

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a after step 3 after step 2 after step 2 307 nm LB film

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Introduction of functionality: Langmuir – Blodgett Monolayers

Analysis of spectral position of defect mode as function of sphere diameter of top and bottom stack if single layer defect in crystal of 415 nm spheres:

conclusion:” impurity “ doping analogous to P- or N-doping in semiconductors, is possible

Langmuir 19, 4465 (2003); Appl. Phys. Lett. 82(21) 3764 (2003), Chem. Phys. Lett. 422, 251 (2006)

Demonstration of periodic nature of defect mode: spectral position of allowedpassband in forbidden stopband shows importance of phase:

Chemical Physics Letters 422, 251-255 (2006) collaboration with Prof. Serge Ravaine, Centre de Recherche Paul Pascal, Université Bordeaux I, France

Chem. Phys. Lett. 422, 251 (2006)

Overview:• Introduction to Photonic Crystals and colloidal PC’s• Photonic heterostructures: BANDGAP ENGINEERING

• Fluorescence inhibition (steady-state) and non-exponential decay (time-resolved)

Spectral narrowing of fluorescence(for LASING)Improved Fluorescence Resonance Energy-

Transfer (FRET) in photonic crystals (for LIGHT HARVESTING)

• Magnetic effects in quantum dots vs. closed shell• New avenues: inverted opals, hollow spheres, titania spheres, vortex

pinning, ...

Fluorescence Inhibition

Fluorescence Inhibition

Chem. Phys. Lett. 421, 1 (2006)

Non-exponential fluorescence decay in photonic crystals: Experiments

Distribution of the most frequent rate γmf in the reference (full) and PSB (dash), ∆γ is a parameter for the width of the distribution

Locally the crystals are quite heterogeneous, the reference more so than the PSB. In the PSB sample, widths are consistently smaller than in the reference samples

Physical Review B 2007, accepted

Non-exponential fluorescence decay in photonic crystals: Simulations

Spectral narrowing of fluorescence

• We were able to insert a 2D defect into a photonic crystal. This was not sufficient to induce spectral narrowing.

• BANDGAP ENGINEERING: heterostructure: broader stopband, deeper and wider passband

Vs.

Spectral narrowing of fluorescence

ABAB heterostructure: Both suppression and enhancement of emission gives spectral narrowing, a necessary, yet not sufficient, condition for LASING!!

J. Appl. Phys. 100, 123112 (2006)

Overview:• Introduction to Photonic Crystals and colloidal PC’s• Photonic heterostructures: BANDGAP ENGINEERING• Fluorescence inhibition (steady-state) and

non-exponential decay (time-resolved)Spectral narrowing of fluorescence (for LASING)

Improved Fluorescence Resonance Energy-Transfer (FRET) in photonic crystals (for LIGHT HARVESTING)

• Magnetic effects in quantum dots vs. closed shell• New avenues: inverted opals, hollow spheres, titania spheres, vortex

pinning, ...

Förster Resonance Energy Transfer (FRET): intro

Figure . The energy transfer efficiency of a Cy3/Cy5 FRET pair[9].

FRET enhancement in photonic crystals: solution benchmark

The distance between a donor (Cy3) and an acceptor (Cy5) was controlled with an oligonucleotide linker. In solution we observe fluorescence resonant energy transfer (FRET). EET is 38% for the red curve and 45% for the black curve.

FRET enhancement in photonic crystals: from 37 to 61% efficiency for LIGHT HARVESTING !!

Chemistry of Materials, accepted

Overview:• Introduction to Photonic Crystals and colloidal PC’s• Photonic heterostructures: BANDGAP ENGINEERING• Fluorescence inhibition (steady-state) and

non-exponential decay (time-resolved)Spectral narrowing of fluorescence(for LASING)Improved Fluorescence Resonance Energy-

Transfer (FRET) in photonic crystals (for LIGHT HARVESTING)

• Magnetic effects in quantum dots vs. closed shell

• New avenues: inverted opals, hollow spheres, titania spheres, vortex pinning, ...

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Possibility to use magnetic field to additionally control the lightPhotonic crystal made from silica filled with

Closed shell organic chromophore: RhodamineB dyeMagnetic particle: CdSe/ZnS quantum dot

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Time resolved fluorescence measurements

RhB

CdSe/ZnS

Overview:• Introduction to Photonic Crystals and colloidal PC’s• Photonic BANDGAP ENGINEERING• Fluorescence inhibition (steady-state) and

non-exponential decay (time-resolved)Spectral narrowing of fluorescence(for LASING)Improved Fluorescence Resonance Energy-

Transfer (FRET) in photonic crystals (for LIGHT HARVESTING)

• Magnetic effects in quantum dots vs. closed shell

• New avenues: inverted opals, hollow spheres, titania spheres, vortex pinning, ...

Inverted opal, in collaboration withChris Summers, GATech:

SEM Analysis:

Large Sphere “defect” layer

Vortex pinning

Nano-engineering magnetic-field inducedsuperconductivity by vortex pinning by periodic arrays of magnetic dots:

Niobium deposited on nanospheres of silicaon mica

Conclusions:

PHOTONIC BANDGAP ENGINEERING in self-assembledcolloidal photonic crystals can provide:

1. spectral narrowing of fluorescence, a necessary (notsufficient) condition for LASING

2. improved energy transfer efficiency for LIGHT HARVESTING

Who

• Kurt Wostyn• Yuxia Zhao• Kai Song, • Wim Libaers, • Kasper Baert, fluorescence, time-resolved• Yanqiu Jiang, titania, hollow spheres• Luis Gonzalez, spincoating photonic crystals• Branko Kolaric, colloid chemistry, FRET, INPAC Postdoc• Renaud Vallée, fluorescence analysis

• Prof. Serge Ravaine, Université Bordeaux I• Prof. Christophe Summers, Georgia Institute of Technology