Ppt t Thongrattanasiri_Metamaterials_g-Ene

7/27/2019 Ppt t Thongrattanasiri_Metamaterials_g-Ene

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Graphene Plasmonics

Sukosin Thongrattanasiri,*

Frank Koppens,# Darrick Chang,$ and Javier Garca de Abajo*,&

*CISC, Madrid#ICFO, Barcelona

$

Caltech, Pasadena&On sabbatical at ORC, Southampton, 2010-2011


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Milestones in Plasmonics

Graphene Plasmonics Metamaterials, October 2011

Experimentally evidence

but not unexplained until 1957 (Ritchie, theory)and 1959 (Powell and Swan, experiment)

Metal plasmons, 1950s

Jablan et al., Phys. Rev. B 80, 245435 (2009)Velizhanin and Efimov, Phys. Rev. B 84, 085401 (2011)Vakil and Engheta, Science 332, 1291 (2011)Chen and Alu, ACS Nano 5, 5855 (2011)Koppens et al., Nano Lett. 11, 3370 (2011)Nikitin et al., arXiv:1104.3558v1 (2011)Sukosin et al., arXiv:1106.4460v1 (2011)

Ju et al., Nature Nanotech. 6, 630 (2011)

Increasing interest from theory

and experimental proof

Graphene plasmons, 2009-2011


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Outline


plasmonic background

graphene background

graphene plasmonics 100% light absorption


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Plasmons

Graphene Plasmonics

plasmons quantum of rapid oscillations of conduction-electrons

surface plasmon - Wikipedia

localized plasmon

Myroshnychenko et al., Chem. Soc. Rev. 37, 1792 (2008)

Metamaterials, October 2011


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Graphene

Graphene Plasmonics

Das Sarma et al., Rev. Mod. Phys. 83, 407 (2011)

a flat monolayer of carbon atoms tightly packed into a 2-dimensionalhoneycomb lattice

Physics World, Nov 2006

= 3 +

Expandingk=K

+q

close toK

(K

) with |q

|


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Unique Properties

Graphene Plasmonics

electrons and holes near Dirac points behave as particles describedby the Dirac equation for -spin particles massless Dirac fermions

vF=106 m/s, similar to noble metals

minimum conductivity at T=0K:

,

,

impurity concentration, rippling, interaction with substrate

high electron mobility at room temperature

large mean free path (up to several microns) extremely good conductor

Crystal mobility (cm2/Vs)

graphene 10,000-200,0001

GaAs 8,0002

GaSb 5,0002

diamond 1,8002

1Geim et al., Nat. Mat. 6, 183 (2007)2Kittel, Introduction to Solid State Physics, 8th ed



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Unique Properties (cont.)

Graphene Plasmonics

high 3D plasmon-confinement: ~106 times smaller thandiffraction limit

tunable material absorption = 2.3% over a broad spectral range



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Optical Response

Graphene Plasmonics

real

imaginary

Falkovsky et al., Eur. Phys. J. B 56, 281 (2007)

Koppens et al., Nano Lett. 11, 3370 (2011)



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Plasmons in a Graphene Sheet

Graphene Plasmonics

Jablan et al., PRB 80, 245435 (2009)

For ,

+




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Graphene vs Gold

1

2

4

|

WZS

Z

V

i

iLp12

2

|

WZS

V

i

iEe F

!

1 monolayer of gold

(L=0.24 nm)graphene

(L=0.33 nm)

L

i

Z

VS

ZH

4|L



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Nanostructured graphene

Graphene Plasmonics

So far graphene, an extended sheet allows

high field confinement

long plasmon propagation (many plasmon wavelength)

But we can gain further benefits by nanostructuring extremely high field confinement

high plasmon localization

engineering plasmon resonances



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1D Plasmon Confinement: Nanoribbons



Width (nm)

Photon

energy(eV)

10.5 0.750.250.01

Extinction V/area

EF=0.2 eVlightE

ext


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0D Plasmon Confinement: Nanodisks

Graphene Plasmonics

=

Im

Sukosin et al., arXiv:1106.4460v1



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Experimental Proof of Nanoribbon Plasmons


Ju et al., Nature Nanotech. 6, 630 (2011)


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Light Absorption in Graphene


At plasmon resonance, an arrayofpatternedgraphene catches the light.

Higher absorption!!


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Absorption by a Thin Layer

Graphene Plasmonics

SymmetricEnvironment

A thin layer patterned with a period smaller than the wavelength canonly produce specularly reflected and transmitted beams (no diffraction).

= 1

= 1 1

= 50%

Full Detail: Sukosin et al., arXiv:1106.4460v1



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Absorption by a Thin Layer

Graphene Plasmonics

AsymmetricEnvironment


, =1

1 + Re

, = 1 Re

Re + /

=1

cos

sin



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Array of Graphene Nanodisks

Graphene Plasmonics

1Garca de Abajo et al., PRB 65, 115418 (2002)2Stefanou et al., Comput. Phys. Commun. 113, 49 (1998)

3Garca de Abajo et al., Rev. Mod. Phys. 79, 1267 (2007)


Numerical1. BEM1 multipolar scattering matrix

of each graphene nanodisk2. multiple-scattering method2 periodic structure

Analytical dipole model3

=

1/

5.52

+

2

3

;

=2

cos

=

2 cos


T l Li h Ab i


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Total Light Absorption

Graphene Plasmonics



T t l Li ht Ab ti O idi ti lit


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Total Light Absorption: Omnidirectionality

Graphene Plasmonics



C l i


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Conclusion

Funding:


Sukosin et al., arXiv:1106.4460v1 (2011)

graphene nanostructure

high field confinement

high plasmon localization

engineering plasmon resonance

omnidirectional total light absorption within an

atomically thick layer

strong light-matter interaction

a new direction in plasmonics metamaterials

more info on graphene plasmonics:

Ppt t Thongrattanasiri_Metamaterials_g-Ene

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