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XCVI Congresso Nazionale – SIF 23/09/10
UNIVERSITÀ DELLA CALABRIA
R. Bartolino, A. De Luca, G. Strangi
C. Umeton, R. Caputo, L. De Sio
MetamaterialiMetamateriali Ottici: Ottici: ““Da Da VeselagoVeselago ad oggiad oggi””
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XCVI Congresso Nazionale – SIF 23/09/10
UNIVERSITÀ DELLA CALABRIA
Cosa è un metamateriale?
Originates from a Greek word metameta: "after/beyond"
Metamaterials are artificially engineered materials possessing properties (e.g., mechanical, optical, electrical) that are not encountered in naturally occurring materials.
Metamaterials (MTMs), as well as photonic crystals (PC) are
composite metamaterials whose properties are not determined by the fundamental physical properties of their constituents but by the shape and distribution of specific patterns included in them.
MTMs have the unique property of having both the effective permittivity and the effectivepermeability negative.
The aim of the research is the theoretical understanding, analysis, development, fabrication and testing of MTMs, and also the investigation of their feasibility for applications.
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XCVI Congresso Nazionale – SIF 23/09/10
UNIVERSITÀ DELLA CALABRIA
Metamaterials:Pubblication /year & /subject area
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XCVI Congresso Nazionale – SIF 23/09/10
UNIVERSITÀ DELLA CALABRIA
k
2E 2Et2
n
V. G. Veselago:“The electrodynamics of substances with simultaneously negative value of ε
and μ,” Sov. Phys. Usp. 10, 509–514 (1968).
0))(( n
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XCVI Congresso Nazionale – SIF 23/09/10
UNIVERSITÀ DELLA CALABRIA
Meta-Materials
History:• Permittivity , permeability and index of refraction n negative• Reversal of Snell’s Law, perfect focusing, flat lenses, etc.• Impedance match z =√
and n = -1
•
>> a in Left Handed Materials, while a in PBG
Both PBG and LHM exhibit properties not found in naturally materials
Vision:• Understanding the physics and the exotic properties of LHMs• Perfect Lens. Near-field optical microscopy, nano-lithography• Wireless and optical communications. RF sensing.• Antenna and microwave device miniaturization________________________________
Breakthroughs and new concepts in materials processing at nanoscale Search for new materials that exhibit
< 0 at THz or optical regime
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XCVI Congresso Nazionale – SIF 23/09/10
UNIVERSITÀ DELLA CALABRIA
Negative materials
< 0 at optical wavelengths leads to important new optical phenomena.
< 0 is possible in many resonant magnetic systems.
What about < 0 and < 0?
Unfortunately, electric and magnetic resonances do not overlap in existing materials.
This restriction doesn’t exist for artificial materials!
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XCVI Congresso Nazionale – SIF 23/09/10
UNIVERSITÀ DELLA CALABRIA
Where are material resonances?
• Most electric resonances are THz or higher.
• For many metals, p occurs in the UV
• Magnetic systems typically have resonances through the GHz (FMR, AFR; e.g., Fe, permalloy, YIG)
• Some magnetic systems have resonances up to THz frequencies (e.g., MnF2 , FeF2 )
• Metals such as Ag and Au have regions where
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XCVI Congresso Nazionale – SIF 23/09/10
UNIVERSITÀ DELLA CALABRIA
Dalle microonde al visibile
Risultati nelle Microonde:- Materiali artificiali (tipo risonatori split-rings) che permettono di ottenere
lunghezze d’onda di risonanza più elevate, alti valori di capacità, basse perdite radiative e fattori di qualità molto elevati.- gestire frequenze comprese tra i 300 GHz e i 10 THz.
Per le onde piane che si propagano in tali metamateriali, il campo elettrico, campo magnetico e il vettore d'onda segue una regola left-hand.
- La Legge di Snell (n1 sinθ1 = n2 sinθ2 ) è ancora valida, ma con n2 negativo, i raggi saranno rifratti dallo stesso lato rispetto alla normale al materiale.- Lo Spostamento Doppler è rovesciato: cioè, una sorgente di
luce muovendosi verso un osservatore sembra ridurre la sua frequenza.- Il vettore di Poynting è antiparallelo alla velocità di fase.
Questo significa che a differenza di un normale materiale right- handed, i fronti dell'onda vengono a muoversi in direzione opposta al flusso di energia.
Frequenze ottiche:I metamateriali con n negativo hanno numerose proprietà sorprendenti:
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XCVI Congresso Nazionale – SIF 23/09/10
UNIVERSITÀ DELLA CALABRIA
Left-Handed Waves
If then is a right set of vectors:
If then is a left set of vectors:
0,0 kHE ,,
0,0 kHE ,,
E
k
H
E
k
H
Ec
Hk
Hc
Ek
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XCVI Congresso Nazionale – SIF 23/09/10
UNIVERSITÀ DELLA CALABRIA
Energy flux (Poynting vector):
Conventional (right-handed) medium
Left-handed medium
Energy flux in plane waves
grV
4S
SEk HSE kH SS
grV
phgr VV
HE4cS
kS
E
k
H
S
E
k
H
S kS
phgr VV
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XCVI Congresso Nazionale – SIF 23/09/10
UNIVERSITÀ DELLA CALABRIA
“Reversal” of Snell’s Law
1
21 2
PIMRHM
PIMRHM
PIMRHM
NIMLHM
(1) (2) (1) (2)
k
S k
S
1) Consequence: phase velocity (along k) and group velocity (along the Poynting vector) are in the same direction
2) In NIMs group and phase velocity are in opposite directions
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XCVI Congresso Nazionale – SIF 23/09/10
UNIVERSITÀ DELLA CALABRIA
RightRight--handedhanded LeftLeft--handedhanded
SourceSource SourceSource
n=1,5 n=-1
n=1
n=1
n=1
n=1
Courtesy of Maria Kafesaki (FORTH Crete)
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XCVI Congresso Nazionale – SIF 23/09/10
UNIVERSITÀ DELLA CALABRIA
Unusual refractive properties of NIMs
Light enters n > 0 material
deflection
Light enters n < 0 material
focusing
(“Veselago Lens”)
Surface waves make Veselago’s lens a super-lens! (Sir J. Pendry, 2000)
Open Cavity
PRL 102, 133902 (2009)
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XCVI Congresso Nazionale – SIF 23/09/10
UNIVERSITÀ DELLA CALABRIA
Metamateriali nel visibile (400-700 THz)
Nel range del visibile, affinchè un mezzo abbia delle caratteristiche di metamateriale, le strutture artificiali realizzate devono presentare taglie tipiche intorno a decine di nanometri, o meno.
Micro- e Nano-litografia/10l
This image was written using Dip-Pen Nanolithography, and imaged using lateral force microscopy mode of an atomic force microscope. Courtesy the Mirkin Group, Northwestern University.
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XCVI Congresso Nazionale – SIF 23/09/10
UNIVERSITÀ DELLA CALABRIA EU Project 7FP - SEVENTH FRAMEWORK PROGRAMME
“METACHEM”Nanochemistry and Self-assembly
Routes to Metamaterials for Visible Light
Coordinating person: Dr. Philippe BAROIS
Participant: CNR - Prof. Roberto BartolinoDr. Antonio De Luca
UNICAL - Dr. Giuseppe StrangiProf. Carlo Versace
THEME 4Nanosciences, Nanotechnologies, Materials and
New Production Technologies
Collaborative Project Small-Scale Focused Research Projects
“NANOGOLD”Self-Organized Nanomaterials for
tailored optical and electrical properties
Coordinating person: Dr. Toralf Scharf
Participant: UNICAL - Prof. Cesare UmetonDr. Roberto Caputo,
Dr. Luciano De SioDr. Marco Castriota, Dr. Luigia Pezzi
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XCVI Congresso Nazionale – SIF 23/09/10
UNIVERSITÀ DELLA CALABRIA
Metachem Participants
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XCVI Congresso Nazionale – SIF 23/09/10
UNIVERSITÀ DELLA CALABRIA
Nanogold Participants
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XCVI Congresso Nazionale – SIF 23/09/10
UNIVERSITÀ DELLA CALABRIA
Obiettivi principali e concetti chiave
Main Objective:creating a radically new generation of metamaterials at infrared
and optical frequencies, based on the use of nano-chemistry and self-assembly of materials
Concept:Nano-scale chemistry and Self-assembly methods (either
spontaneous or directed), with the combined aid of theory and EM analysis methods, towards development of possible
technological devices with unusual properties.
METACHEM
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XCVI Congresso Nazionale – SIF 23/09/10
UNIVERSITÀ DELLA CALABRIA
Obiettivi principali e concetti chiave
Main Objective:The NANOGOLD project aims at the fabrication and application of bulk
electro-magnetic metamaterials. We will apply self-organization of organic- inorganic composite materials containing resonant entities.
Concept:To tune and optimize electromagnetic properties, resonance and interference
at different length scales will be implemented. In such a way we will obtain bulk optical metamaterials with unprecedented properties operating in spectral
domains appropriate for photonics that can be used in applications. Proof of principle devices will be the outcome of the project.
NANOGOLD
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XCVI Congresso Nazionale – SIF 23/09/10
UNIVERSITÀ DELLA CALABRIA
Reconfigurable metamaterials
The tunability
in the optical range can be
accomplished by incorporating electro-optically active materials such as liquid crystals into NIM structures.
Tuning or switching and other modulation processes can be performed electro–optically or all-
optically
To provide full operational functionality for optical NIM devices, they can be complemented by integrated tunable
elements.
The unique properties of liquid crystals such as:
• compatibility with almost NIMs; • broadband transparent 0.4 μm to 20 μm; • large optical birefringence;• and ultrahigh nonlinearities.
Appl. Phys. Lett. 97, 091101 (2010)
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XCVI Congresso Nazionale – SIF 23/09/10
UNIVERSITÀ DELLA CALABRIA Nano-chimica e Self-assembly vs nanolitografia
J.-F. Dechézelles, et al. Colloids and Surfaces A: Physicochem. Eng. Aspects 343 (2009)
T. Placido, et al. Chem. Mat. 21 (18), (2009)
Nano-chimica
Self-assembly
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XCVI Congresso Nazionale – SIF 23/09/10
UNIVERSITÀ DELLA CALABRIA
Template assisted MTMs nell’infrarosso
Liu et al. Adv. Mater. 2008, 20, 2050–2054
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XCVI Congresso Nazionale – SIF 23/09/10
UNIVERSITÀ DELLA CALABRIA
Compensazione delle perdite in MTMs
Presenza di perdite ottiche in MTMs
Per riflessionePer assorbimento
(in termini di
grandi
n′′) (all’interfaccia)
Devono essere compensate attraverso l’inclusione di materiali di guadagno
Possibilità di essere soppresse attraverso un design ottimizzato di
un’impedenza ben accoppiata e/o dei gradienti delle proprietà EM
Capace di transferire energia ai polaritoni di superficie ed ai
plasmoni localizzati alla sup. nelle strutture metalliche, tramite
emissione stimolata
Dyes , quantum dots, semiconductor nanocrystals;
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XCVI Congresso Nazionale – SIF 23/09/10
UNIVERSITÀ DELLA CALABRIA
Metodologie proposte (nano-, meso- e macro-scala)
Approccio multiplo basato essenzialmente sull’inclusione di materiali di guadagno attraverso processi “guest-host” e funzionalizzazione per creare un guadagno stabile in metamateriali attivi
Guest Guest --
HostHostFunzionalizzazioneFunzionalizzazione
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XCVI Congresso Nazionale – SIF 23/09/10
UNIVERSITÀ DELLA CALABRIA
Demonstration of meta-EM properties
A work package will consists of two equally important overall aims:
to measure optical properties of fabricated metamaterials which imposes to extract relevant optical constants (permittivity, permeability, index of refraction) from these measurements.
to demonstrate and study extraordinary optical properties of metamaterials, such as negative optical phase, optical impedance matching and negative Snell’s angle.
PRL 102, 053901 (2009)PRB 79, 241104R 2009
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XCVI Congresso Nazionale – SIF 23/09/10
UNIVERSITÀ DELLA CALABRIA
“METACHEM”Nanochemistry and Self-assembly Routes to
Metamaterials for Visible Light
Coordinating person: Dr. Philippe BAROIS
Participant: CNR - Prof. Roberto BartolinoDr. Antonio De Luca
UNICAL - Dr. Giuseppe StrangiProf. Carlo Versace
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XCVI Congresso Nazionale – SIF 23/09/10
UNIVERSITÀ DELLA CALABRIA
Tecniche sperimentali utilizzate
FluorescenceConfocal Microscopy
TEM & SEM
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XCVI Congresso Nazionale – SIF 23/09/10
UNIVERSITÀ DELLA CALABRIA
Primi risultati su NPs core/shell dopate
FluorescenceFluorescence Quenching of Quenching of dyedye moleculesmoleculesnearnear Gold Gold CoreCore--ShellShell NpsNps
Au CoreAu Core57 57 ±±
7 7 nmnm
SilicaSilica ShellShell30 30 ±±
2 2 nmnm
h
d
C522B C522B DyeDye400 450 500 550 600 650 700 7500
1
2
3
4
5
6
7 A)
Wavelength (nm)
Nps C
ore-shell Absorbance (a.u.)
Fl
uore
scen
ce (a
rb. u
nits
) C522B Au-C522B
PumpPump @ 355nm@ 355nm
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XCVI Congresso Nazionale – SIF 23/09/10
UNIVERSITÀ DELLA CALABRIA
Primi risultati su NPs core/shell dopate
1400 1500 1600 1700 1800 19000.0
0.5
1.0
1.5
2.0
2.5
3.0
Log
Cou
nts
Chanels
Promt Decay Au@SiO2/OD Fit Au@SiO2/OD Decay OD in solution Fit OD in solution
Fluorescence
life time in presence
of GNPs
(from
2.9 10-9
to
1.8 10-9s)Fluorescence
life time in presence
of GNPs
(from
2.9 10-9
to
1.8 10-9s)
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XCVI Congresso Nazionale – SIF 23/09/10
UNIVERSITÀ DELLA CALABRIA
Primi risultati su NPs core/shell dopate
50 100 150 200 250 300 350 400 450 500
02468
101214161820
Tran
sm. I
nten
sity
(arb
. uni
ts)
Pump Energy (@355nm) (J)
B)
Trasparenza indotta
0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5
5
10
15
20
25
300 400 500 600 700 800
0
5
10
15
20
25
Sca
ttere
d In
tens
ity (a
rb.u
nits
)
Pump Energy (mJ)
A)
Inte
nsity
(arb
. uni
ts)
Wavelength (nm)
Aumento Scattering Rayleigh
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XCVI Congresso Nazionale – SIF 23/09/10
UNIVERSITÀ DELLA CALABRIA
Includiamo il guadagno nella shell
-0.5 0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5
10
20
30
40
50
60
70
Threshold ~ 0.96 mJ
Sca
ttere
d In
tens
ity (a
rb. u
nits
)
Pump Energy (mJ)
h
EncapsulatedEncapsulated R6G R6G DyeDye/ or C500/ or C500
PumpPump @ 355nm@ 355nm
0 1 2 3 4 5 60.8
1.0
1.2
1.4
1.6
1.8
2.0
2.2
2.4
A)
@ 490 nm @ 500 nm @ 510 nm @ 520 nm @ 540 nm
Sca
ttere
d In
tens
ity (a
rb. u
nits
)
Pump Energy (mJ)
Misura Broadband
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XCVI Congresso Nazionale – SIF 23/09/10
UNIVERSITÀ DELLA CALABRIA
Includiamo il guadagno nella shell
0.0 0.5 1.0 1.5 2.0 2.5
-1.0
-0.5
0.0
0.5
1.0
1.5
2.0
2.5
3.0
Nor
mal
ized
Inte
nsity
(arb
.uni
ts)
Pump Energy (mJ)
@460 nm @480 nm @500 nm @520 nm @540 nm @560 nm @580 nm
B)Out ofOut of
resonanceresonance
450 480 510 540 570 600 630 660 690 720 750 780 810
0
1
2
3
4
5
Abs_sam
ple_S1
Fluo
resc
ence
(arb
. uni
ts)
Wavelength (nm)
506 nmTrasparenza indotta (broadband)
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XCVI Congresso Nazionale – SIF 23/09/10
UNIVERSITÀ DELLA CALABRIA
“NANOGOLD”Self-Organized Nanomaterials for tailored optical and
electrical properties
Coordinating person: Dr. Toralf Scharf
Participant: UNICAL - Prof. Cesare UmetonDr. Roberto Caputo,
Dr. Luciano De SioDr. Marco Castriota, Dr. Luigia Pezzi
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XCVI Congresso Nazionale – SIF 23/09/10
UNIVERSITÀ DELLA CALABRIA
POLICRYPS as POLYMER MATRIX
POSSIBLE APPLICATIONS:
• OPTOFLUIDICS
• PHOTONIC SENSORS
• MAGNETIC DIFFRACTION
• DYE LASERS
• OPTICAL MICROCHANNELS
• WAVEGUIDE ARRAYS
•...........
• META-MATERIALS ?
PATENT APPLICATION N° CZ2009A000021
The final system is a periodic structure of polymer walls alternated to empty channels
AA PP
POLICRYPS: POlymer LIquid CRYstal Polymer Slides
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XCVI Congresso Nazionale – SIF 23/09/10
UNIVERSITÀ DELLA CALABRIA
Filling the template with NPsFilling the template with NPs
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XCVI Congresso Nazionale – SIF 23/09/10
UNIVERSITÀ DELLA CALABRIA
Filling the template with NPsFilling the template with NPs
Struttura 2D olografica
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XCVI Congresso Nazionale – SIF 23/09/10
UNIVERSITÀ DELLA CALABRIA
Meta-POLICRYPS with Silver NPs (~25nm)
400 500 600
0
10
20
30 MixtureT3T2
T0T1
Tran
smitt
ance
%
Wavelength (nm)
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XCVI Congresso Nazionale – SIF 23/09/10
UNIVERSITÀ DELLA CALABRIA
Possibili applicazioni: nanolaser plasmonici
Demonstration of a spaser-based nanolaserM. A. Noginov et al., Nature Vol 460 (2009)
Plasmon lasers at deep subwavelength scaleOulton et al. Nature, Vol 461 (2009)
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XCVI Congresso Nazionale – SIF 23/09/10
UNIVERSITÀ DELLA CALABRIA
Biosensori, superlenti ed invisibilità
BiosensorsMetamaterials can be used to provide more sensitive guiding modes (based on plasmon-mediated interaction between the inclusions which shows resonant excitation conditions).The metamaterial inclusions can be functionalised with receptors on theirsurface. If the matrix consists of nanoporous material it allows analytesto reach the receptor and the refractive index will be changed upon binding. The reflection spectrum depends on this refractive index.
SuperlensA superlens (or perfect lens) is a lens, which uses metamaterials to gobeyond the diffraction limit. The diffraction limit is an inherent limitation in conventional optical devices or lenses. A lens consisting of a negative index metamaterial could compensate for wave decay and could reconstructImages in the near field. In addition, both propagating and evanescent waves contribute to the resolution of the image and resolution underneath the diffraction limit will be possible.
CloakingA cloaking device is an advanced stealth technology that causes an object to be partially or wholly invisible to parts of the electromagnetic (EM) spectrum (at least one wavelength of EM emissions) Scientists are using metamaterials to bend light around an object.
Tags to store and process informationA remote detection via high-frequency electromagnetic fields will be possible due to the collective response of magnonic crystals at elevated frequencies.
Metamateriali Ottici: �“Da Veselago ad oggi”Cosa è un metamateriale?Metamaterials:Pubblication /year & /subject areaSlide Number 4Slide Number 5Negative materialsWhere are material resonances?Dalle microonde al visibileLeft-Handed WavesSlide Number 10Slide Number 11Slide Number 12Unusual refractive properties of NIMsMetamateriali nel visibile (400-700 THz)Slide Number 15Metachem ParticipantsNanogold ParticipantsObiettivi principali e concetti chiaveObiettivi principali e concetti chiaveReconfigurable metamaterialsNano-chimica e Self-assembly vs nanolitografiaTemplate assisted MTMs nell’infrarossoCompensazione delle perdite in MTMsMetodologie proposte (nano-, meso- e macro-scala)Demonstration of meta-EM propertiesSlide Number 26Tecniche sperimentali utilizzatePrimi risultati su NPs core/shell dopatePrimi risultati su NPs core/shell dopatePrimi risultati su NPs core/shell dopateIncludiamo il guadagno nella shellIncludiamo il guadagno nella shellSlide Number 33Slide Number 34Slide Number 35Slide Number 36Meta-POLICRYPS with Silver NPs (~25nm)Possibili applicazioni: nanolaser plasmoniciBiosensori, superlenti ed invisibilità