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Optics Express

Optics Express

  • Editor: C. Martijn de Sterke
  • Vol. 17, Iss. 24 — Nov. 23, 2009
  • pp: 22012–22022
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Anisotropy and particle-size effects in nanostructured plasmonic metamaterials

I. Romero and F. J. García de Abajo  »View Author Affiliations


Optics Express, Vol. 17, Issue 24, pp. 22012-22022 (2009)
http://dx.doi.org/10.1364/OE.17.022012


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Abstract

We study the optical properties of metamaterials formed by layers of metallic nanoparticles. The effective optical constants of these materials are retrieved from the calculated angle-dependent Fresnel reflection coefficients for s and p incident-light polarization. We investigate the degree of anisotropy in the effective permittivity as a function of inter-layer spacing, particle size, filling fraction of the metal, and particle shape. For layers of spherical particles periodically arranged in a hexagonal lattice, the anisotropy disappears for the three inter-layer spacings corresponding to simple cubic (sc), bcc, and fcc volume symmetry. For non-spherical particles, an isotropic response can be still obtained with other values of the inter-layer spacing. Finally, we provide a quantitative answer to the question of how many layers are needed to form an effectively homogeneous metamaterial slab. Surprisingly, only one layer can be enough, except in the spectral range close to the particle plasmon resonances.

© 2009 Optical Society of America

1. Introduction

The problem of obtaining the effective optical properties of composite materials has been addressed for a long time. The Clausius-Mossotti (CM) formula [20

20. J. D. Jackson, Classical Electrodynamics (Wiley, New York, 1999).

] relates the polarizability of small particles to the effective permittivity of an aggregate with either inversion symmetry or full disorder. This formula gives a reasonable description of the response of small-particle arrays, described through their dipolar response, and it is the basis of the Maxwell-Garnett (MG) theory [21

21. J. C. Maxwell-Garnett, Philos. Trans. R. Soc. London, Ser. A203, 385 ( 1904); 205, 237 ( 1906). [CrossRef]

] for obtaining the effective permittivity of a matrix material containing spherical inclusions of another material, with the permittivities of these media and the filling fraction of the inclusions f as the only parameters. When the shape of the constituent materials is not spherical, Bruggeman’s theory [22

22. D. A. G. Bruggeman, “Calculation of various physics constants in heterogenous substances. Dielectricity constants and conductivity of mixed bodies from isotropic substances,” Ann. Phys. (Leipzig) 24, 636–664 ( 1935).

] can yield reasonable results in some cases, although it is generally better to use MG theory for spherical objects. However, both of these models fail at large filling fractions [23

23. M. F. MacMilland, R. P. Devaty, and J. V. Mantese, “Infrared properties of Pt/Al2O3 cermet films,” Phys. Rev. B 43, 13,838–13,845 ( 1991).

, 24

24. R. Sainidou and F. J. García de Abajo, “Plasmon guided modes in nanoparticle metamaterials,” Opt. Express 16, 4499–4506 ( 2008). [CrossRef] [PubMed]

]. More sophisticated theories have been presented, based upon spectral representations [25

25. D. J. Bergman, “Dielectric constant of a two-component granular composite: A practical scheme for calculating the pole spectrum,” Phys. Rev. B 19, 2359–2368 ( 1979). [CrossRef]

, 26

26. P. Sheng, “Theory for the dielectric function of granular composite media,” Phys. Rev. Lett. 45, 60–63 ( 1980). [CrossRef]

, 27

27. G. W. Milton, “Bounds and exact theories for the transport properties of inhomogeneous media,” Appl. Phys. A-Mater. Sci. Process. 26, 207–220 ( 1981). [CrossRef]

, 28

28. R. Fuchs, R. G. Barrera, and J. L. Carrillo, “Spectral representations of the electron energy loss in composite media,” Phys. Rev. B 54, 12,824–12,834 ( 1996). [CrossRef]

]. The extension to higher multipoles beyond the dipoles leads to quasi-analytical results that have been worked out for several kinds of cubic lattices [29

29. D. R. McKenzie and R. C. McPhedran, “Exact modeling of cubic lattice permittivity and conductivity,” Nature 265, 128–129 ( 1977). [CrossRef]

, 30

30. R. C. McPhedran and D. R. McKenzie, “The conductivity of lattices of spheres. I. The simple cubic lattices,” Proc. R. Soc. London, Ser. A 359, 45–63 ( 1978). [CrossRef]

, 31

31. D. R. McKenzie, R. C. McPhedran, and G. H. Derrick, “The conductivity of lattices of spheres. II. The body centred and face centred cubic lattices,” Proc. R. Soc. London, Ser. A 362, 211–232 ( 1978). [CrossRef]

]. The effect of particle shape has also been investigated [32

32. F. Wu and K. W. Whites, “Quasi-static effective permittivity of periodic composites containing complex shaped dielectric particles,” IEEE Trans. Antennas Propag. 49, 1174–1182 ( 2001). [CrossRef]

, 33

33. K. W. Whites and F. Wu, “Effects of particle shape on the effective permittivity of composite materials with measurements for lattices of cubes,” IEEE Trans. Microw. Theory Tech. 50, 1723–1729 ( 2002). [CrossRef]

, 34

34. S. B. Jones and S. P. Friedman, “Particle shape effects on the effective permittivity of anisotropic or isotropic media consisiting of aligned or randomly oriented ellipsoidal particles,” Water Resour. Res. 36, 2821–2833 ( 2000). [CrossRef]

]. Other developments include extensions of MG theory to chiral mixtures [35

35. A. H. Sihvola and I. V. Lindell, “Chiral Maxwell-Garnett mixing formula,” Electron. Lett. 26, 118–119 ( 1990). [CrossRef]

], analysis of randomly oriented anisotropic particles [36

36. J. S. Ahn, K. H. Kim, T.W. Noh, D. H. Riu, K. H. Boo, and H. E. Kim, “Effective-medium theories for spheroidal particles randomly oriented on a plane: Application to the optical properties of a SiC whisker-Al2O3 composite,” Phys. Rev. B 52, 15,244–15,252 ( 1995).

], and nonlocal effects resulting from the microscopic granularity in composite materials [37

37. R. G. Barrera and R. Fuchs, “Theory of electron energy loss in a random system of spheres,” Phys. Rev. B 52, 3256–3273( 1995). [CrossRef]

].

In this work, we solveMaxwell’s equations rigorously for metamaterials formed by layers of metallic nanoparticles periodically disposed in a hostmedium. A scheme of the system is shown in Fig. 1. We discuss both spherical (isotropic) and ellipsoidal (anisotropic) nanoparticles. The difference in shape affects the degree of anisotropy of themetamaterial response. We investigate the optical response of these materials by first calculating their reflection coefficients, which are then compared to those of homogeneous anisotropic semi-infinite media, thus leading to the determination of effective optical constants.

We calculate the Fresnel reflection coefficients Rs and Rp for s- and p-polarized light using a rigorous layer-KKR method [38

38. N. Stefanou, V. Yannopapas, and A. Modinos, Comput. Phys. Commun.113, 49 ( 1998); 132, 189 ( 2000). [CrossRef]

, 39

39. N. Stefanou, V. Yannopapas, and A. Modinos, “MULTEM 2: A new version of the program for transmission and band-structure calculations of photonic crystals,” Comput. Phys. Commun. 132, 189–196 ( 2000). [CrossRef]

]. In this method, an incident plane wave is expanded in spherical waves centered around the particles, and the scattered outgoing spherical waves are re-expressed in terms of plane waves that describe the propagation of the electromagnetic field between consecutive particle planes. The reflection coefficients result from the self-consistent solution for the amplitude of the spherical and plane waves involved. We use a finite number of multiples with orbital momentumnumber ll max. The results presented below have converged for l max=12. The number of plane waves that mediate the inter-layer interaction is also limited to a finite set around the specular reflection direction, with good convergence achieved for ~300 waves in the calculations here reported. This method has been previously used to study isotropic nanoparticle-based metamaterials [40

40. S. Riikonen, I. Romero, and F. J. García de Abajo, “Plasmon tunability in metallodielectric metamaterials,” Phys. Rev. B 71, 235,104 ( 2005). [CrossRef]

].

Fig. 1. Schematic view of the system under study, consisting of planar periodic arrays of spherical or ellipsoidal nanoparticles with hexagonal symmetry. Two geometrical parameters characterize the lattice of the structure: the inter-layer spacing dz and the inter-particle spacing within each layer d. Consecutive layers are laterally offset a distance d/√3 along the (1,1) layer direction. A close-packed structure is obtained for dz=2d/√6.

The values of Rs and Rp obtained by means of the layer-KKR method are then compared to those of a homogeneous anisotropic semi-infinite material, which we obtain from a straightforward generalization of the methods of Ref. [20

20. J. D. Jackson, Classical Electrodynamics (Wiley, New York, 1999).

]:

Rs=cosθαγsin2θcos+αγsin2θ
(1)

and

Rp=cosθα1βsin2θcosθ+α1βsin2θ,
(2)

where

α=εeffμeff,
(3)
β=1εeffεeff,
(4)
γ=1μeffμeff,
(5)

ε eff and µ eff are the electric permittivity and the magnetic permeability of the homogenous medium, the symbols ‖ and ⊥ refer to the response to field components parallel and perpendicular to the surface of the material (i.e., to the particle planes), respectively, and θ is the angle of incidence. By construction, the material response is isotropic with respect to the surface plane directions.

2. Anisotropy due to lattice structure

We first consider systems formed by two-dimensional hexagonal arrays of spherical silver nanoparticles and discuss the anisotropy produced by non-cubic lattices. In order to avoid retardation effects in this preliminary discussion, the nearest-neighbor distance in each layer has been chosen d=6 nm in the calculations that follow, and we neglect nonlocal effects, which should be significant for these small dimensions [44

44. U. Kreibig and M. Vollmer, Optical Properties of Metal Clusters (Springer-Verlag, Berlin, 1995).

, 45

45. F. J. García de Abajo, “Nonlocal effects in the plasmons of strongly interacting nanoparticles, dimers, and waveguides,” J. Phys. Chem. C 112, 17,983–17,987 ( 2008). [CrossRef]

]. We also keep the filling fraction f (i.e., the metal volume fraction) constant. This is done by simultaneously modifying the radius of the spheres r (and thus their volume) and the distance between layers dz (see Fig. 1). The effective dielectric constant is then calculated for fixed f and for a range dz values.

For three specific different values of inter-layer distance dz, 3D cubic lattices are obtained, with the layers under consideration oriented perpendicular to the 〈111〉 direction. More precisely, for dz=d/2√6, dz=d/√6, and dz=2d/√6 we obtain a body-centered cubic lattice (bcc), a simple cubic lattice (sc), and a face-centered cubic lattice (fcc). In these particular instances, the system becomes isotropic. For other inter-layer distances, the response of the system is anisotropic.

The response of sc and fcc lattices is represented in Fig. 2 for a filling fraction of 30% within a range of wavelengths containing the dominant plasmonic response of the system. The actual quantity shown in the figure is Im{-1/e ε eff}, the so-called loss function, which can be directly measured using electron energy-loss spectroscopy [46

46. R. F. Egerton, Electron Energy-Loss Spectroscopy in the Electron Microscope (Plenum Press, New York, 1996).

] and exhibits a pronounced peak near the vanishing of the real part of the dielectric function (Re{ε eff}=0), signaling the existence of a bulk plasmon resonance. The loss function is isotropic for sc and fcc lattices, but it is anisotropic for values of dz corresponding to non-cubic lattices. This is the case of the dz/d=1.31 lattice considered in Fig. 2, in which the degeneracy of bulk plasmons is broken for directions parallel and perpendicular to the layers (the difference in plasmon wavelength is ~10nm).

We have calculated spectra for a range of dz values and represented the plasmon resonance wavelengths as a function of dz/d for both field orientations in Fig. 3. The values of dz/d corresponding to the three cubic lattices are marked by vertical dashed lines. In these three cases, both the parallel and perpendicular components of the dielectric tensor exhibit plasmon resonance peaks at the same wavelength. Plasmons associated to parallel or perpendicular polarization with respect to the layer planes have different wavelengths except for these three crossing points of cubic symmetry. Two different filling fractions of the metal are considered in Fig. 3 (30% and 40%). The behavior is similar in both cases, but the higher filling fraction leads to lower plasmon wavelengths, which is due to stronger inter-particle interaction [40

40. S. Riikonen, I. Romero, and F. J. García de Abajo, “Plasmon tunability in metallodielectric metamaterials,” Phys. Rev. B 71, 235,104 ( 2005). [CrossRef]

]. These conclusions are valid both for silver particles in vacuum and for gold particles in silica, although this latter system is of course more realistic.

Fig. 2. Spectral optical response of layered systems formed by spherical silver nanoparticles for fixed spacing within each layer and fixed filling fraction of the metal (f=30%). Various values of the spacing between consecutive layers are considered: dz=d/√6≈0.41d (isotropic simple-cubic lattice), dz=2d/√6≈0.82d (isotropic fcc lattice), and dz=1.31d (anisotropic lattice with different response to electric fields parallel and perpendicular to the particle layers).
Fig. 3. Dependence of the bulk-plasmon resonance wavelength on inter-layer spacing dz for spherical silver particles arranged as described in Fig. 1. We represent the two plasmons associated to polarization parallel and perpendicular to the particle layers, respectively. These plasmons are degenerate for values of dz corresponding to isotropic cubic lattices. Two different values of the filling fraction of the metal have been considered. (a) Silver spheres in vacuum. (b) Gold spheres in silica.
Fig. 4. Dependence of the bulk-plasmon resonance wavelength on the aspect ratio r /r of ellipsoidal silver particles arranged in layered structures as depicted in Fig. 1. The filling fraction of the metal is 40% in all cases. Three different values of dz are considered. Plasmon energies corresponding to electric polarization parallel (broken curves) and perpendicular (solid curves) with respect to the particle layers are displayed. The two plasmons are degenerate for specific values of the aspect ratio. This occurs for spheres in a fcc lattice, but non-spherical particles can produce isotropic response in non-cubic lattices (see crossing points of solid and broken curves).

3. Anisotropy due to particle shape

We have so far studied anisotropy in spherical-particle arrays due to a departure from cubiclattice symmetry. Anisotropy can also result from changes in particle shape even for cubic lattices. In this section, we study ellipsoidal particles, which unlike the spheres, cannot be handled analytically, and therefore, we have used the highly convergent boundary element method (BEM) [47

47. F. J. García de Abajo and A. Howie, “Relativistic electron energy loss and electron-induced photon emission in inhomogeneous dielectrics,” Phys. Rev. Lett. 80, 5180–5183 ( 1998). [CrossRef]

, 48

48. F. J. García de Abajo and A. Howie, “Retarded field calculation of electron energy loss in inhomogeneous dielectrics,” Phys. Rev. B 65, 115,418 ( 2002). [CrossRef]

] to obtain the scattering matrix of the particles, and these are in turn introduced in the layer-KKR method described above to calculate effective permittivities.

We represent in Fig. 4 the loss function Im{-1/ε eff} for layered materials as a function of the aspect ratio of the particles r /r , where r and r are the ellipsoids semi-axes along directions parallel and perpendicular to the particle layers, and the ellipsoids are taken to be axially symmetric with respect to the layer normal direction. The geometrical parameters are varied in such a way that the metal filling fraction is kept constant. Three different values of dz/d are considered, leading to two different plasmon resonances for electric-field polarization either parallel or perpendicular to the layers. However, these plasmons are degenerate for specific values of the ellipsoids aspect ratio that depend on dz/d. The fcc lattice predicts full degeneracy for spheres (r =r ), but isotropic behavior is observed in non-cubic lattices for oblate ellipsoids (r <r ) at short inter-layer spacings and for prolate ellipsoids (r >r ) in the opposite case. The anisotropy due to the lattice is compensated by the anisotropy produced by the particle shape in the crossing points at which degeneracy occurs.

4. Limits to homogenization

Fig. 5. Left panels: effective dielectric function of a fcc lattice of silver spheres for different sizes of the particles (radius r=5×10-4 nm, r=5nm, and r=20nm, see labels). Right panels: representation of α 2 β/γ-1 [see Eqs. (3), (4), and (5)]. The filling fraction of the metal is 40% in all cases.

Fig. 6. Normal-incidence reflectance for systems of 1, 2, 4, and ∞ layers of silver nanospheres (solid curves) compared to the reflectance of the equivalent homogeneous layers with effective dielectric function (broken curves). The layers are arranged in a fcc lattice and the sphere radius is r=5 nm (left) and r=20 nm (right). The thickness of the homogeneous layers is taken to be equal to the number of spheres times the inter-layer distance dz.
Fig. 7. Normal-incidence transmittance for the same systems as in Fig. 6.

5. How many layers are needed to form a metamaterial

The concept of an effective permittivity is useful to describe the optical response of a metamaterial molded into arbitrary shapes, rather than having to deal with the detailed arrangement of particles that form it. Now, the question arises, what is the minimum size for which a piece of metamaterial still behaves as an effective homogeneous medium tailored into the same shape. We address this question here by studying the reflectance and transmittance of films formed by just a few particle layers.

In Figures 6 and 7 we show the normal-incidence reflectance and transmittance of films formed by 1, 2, 4, and 225 (opaque film) particle layers (solid curves) arranged in a close-packed (fcc) structure with metal filling fraction of 40%. We have considered two different sizes of the spheres (radius r=5nm and r=20nm). We compare these results with the reflectance and transmittance of homogeneous films made of an effective material (broken curves). The effective dielectric function of the homogeneous material is calculated as explained above for a semi-infinite metamaterial of the same metal filling fraction in the electrostatic limit (r→0). The thickness of the homogeneous film is taken to be the number of layers times the inter-layer spacing dz (even for a single layer, the value of dz corresponding to the fcc(111) structure is the appropriate one; we have verified this by calculating the reflectance for f=10% (not shown), in which case rdz, so that the actual choice of thickness in the effective homogeneous film is not so obvious). Interestingly, the homogeneous-film model works rather well even for a single layer, although there are some discrepancies within the spectral region of the plasmon resonances, and the model does not work above ~400nm for spheres of radius r=20nm. This was expected, since we are using the electrostatic effective dielectric function for the homogeneousmedium, so that retardation effects become already important for 40 nm particles, as discussed in Sec. 4.

Fig. 8. Dependence of the reflectance on angle of incidence at fixed wavelength λ=360nm for p-polarized light on the same systems as in Fig. 6.

Further support to these results in provided by Fig. 8, in which the reflectance is studied as a function of incidence angle for the same systems as in Figs. 6 and 7, with particle radius r=5nm and fixed wavelength λ=360nm. The effective-homogeneous-film model works extremely well down to the single layer over a wide range of angles of incidence.

6. Conclusion

We have addressed the anisotropic optical response of multilayered metamaterials made of nanoparticles, in which the structure of the lattice and the shape of the particles can produce anisotropy. Interestingly, these two sources can cancel each other, resulting in specific configurations of non-spherical particles arranged in non-cubic lattices but yielding isotropic optical properties.

We have obtained significant deviations in the actual response of particle arrays with respect to the electrostatic limit for particles as small as 10–20 nm at visible wavelengths. Therefore, we conclude that one has to be careful when homogenizing the response of a composite system, as particle-size-dependent effects can be important even for small sizes compared to the wavelength, particularly near the plasmon resonances.

Surprisingly, a single layer of nanoparticles can behave like a homogeneousmaterial with the effective permittivity of an infinite metamaterial formed by layers arranged in a close-packed structure. This result is useful to assess the conditions under which a nanoparticle-based metamaterial can be assimilated to an effective homogeneous medium. Further work is still needed to explore the validity of the effective-homogeneous-medium assumption for metamaterials tailored into other non-planar shapes.

Acknowledgments

This work has been supported by the Spanish MICINN (MAT2007-66050 and Consolider NanoLight.es) and by the EU (NMP4-2006-016881-SPANS and NMP4-SL-2008-213669-ENSEMBLE).

References and links

1.

T. J. Yen, W. J. Padilla, N. Fang, D. C. Vier, D. R. Smith, J. B. Pendry, D. N. Basov, and X. Zhang, “Terahertz magnetic response from artificial materials,” Science 303, 1494–1496 ( 2004). [CrossRef] [PubMed]

2.

D. R. Smith, J. B. Pendry, and M. C. K. Wiltshire, “Metamaterials and negative refractive index,” Science 305, 788–792 ( 2004). [CrossRef] [PubMed]

3.

A. Boltasseva and V. M. Shalaev, “Fabrication of optical negative-index metamaterials: Recent advances and outlook,” Metamaterials 2, 1–17 ( 2008). [CrossRef]

4.

J. B. Pendry, “Negative refraction makes a perfect lens,” Phys. Rev. Lett. 85, 3966–3969 ( 2000). [CrossRef] [PubMed]

5.

J. B. Pendry, D. Schurig, and D. R. Smith, “Controlling electromagnetic fields,” Science 312, 1780–1782 ( 2006). [CrossRef] [PubMed]

6.

D. Schurig, J. J. Mock, B. J. Justice, S. A. Cummer, J. B. Pendry, A. F. Starr, and D. R. Smith, “Metamaterial electromagnetic cloak at microwave frequencies,” Science 314, 977–980 ( 2006). [CrossRef] [PubMed]

7.

W. S. Cai, U. K. Chettiar, A. V. Kildishev, and V. M. Shalaev, “Optical cloaking with metamaterials,” Nat. Photonics 1, 224–227 ( 2007). [CrossRef]

8.

L. M. Liz-Marzán, “Tailoring surface plasmon through the morphology and assembly of metal nanoparticles,” Langmuir 22, 32–41 ( 2006). [CrossRef]

9.

A. Taleb, V. Russier, A. Courty, and M. P. Pileni, “Collective optical properties of silver nanoparticles organized in two-dimensional superlattices,” Phys. Rev. B 59, 13,350–13,358 ( 1999). [CrossRef]

10.

D. Zanchet, M. S. Moreno, and D. Ugarte, “Anomalous packing in thin nanoparticle supercrystals,” Phys. Rev. Lett. 82, 5277–5280 ( 1999). [CrossRef]

11.

M. Gadenne, V. Podolskiy, P. Gadenne, P. Sheng, and V. M. Shalaev, “Plasmon-enhanced absorption by optical phonons in metal-dielectric composites,” Europhys. Lett. 53, 364–370 ( 2001). [CrossRef]

12.

F. Caruso, M. Spasova, V. S. no Maceira, and L. M. Liz-Marzán, “Multilayer assemblies of silica-encapsulated gold nanoparticles on decomposable colloid templates,” Adv. Mater. 13, 1090–1094 ( 2001). [CrossRef]

13.

T. Ung, L. M. Liz-Marzán, and P. Mulvaney, “Optical properties of thin films of Au@SiO2 particles,” J. Phys. Chem. B 105, 3441–3452 ( 2001). [CrossRef]

14.

H. Fan, K. Yang, D. M. Boye, T. Sigmon, K. J. Malloy, H. Xu, G. P. López, and C. J. Brinker, “Self-assymbly of ordered, robust, three-dimensional gold nanocrystal/silica arrays,” Science 304, 567 ( 2004). [CrossRef] [PubMed]

15.

H. Contopanagos, C. A. Kyriazidou, W. M. Merrill, and N. G. Alexópoulos, “Effective response functions for photonic bandgap materials,” J. Opt. Soc. Am. A 16, 1682–1699 ( 1999). [CrossRef]

16.

Z. Wang, C. T. Chan, W. Zhang, N. Ming, and P. Sheng, “Three-dimensional self -assembly of metal nanoparticles: Possible photonic crystal with a complete gap below the plasma frequency,” Phys. Rev. B 64, 113,108 ( 2001). [CrossRef]

17.

A. A. Zakhidov, R. H. Baughman, I. I. Khayrullin, I. A. Udad, M. Kozlov, N. Eradat, V. Z. Vardeny, M. Sigalas, and R. Biswas, “Three-dimensionally periodic conductive nanostructures: network versus cermet topologies for metallic PGB,” Synthetic Metals 116, 419–426 ( 2001). [CrossRef]

18.

P. Xu and Z. Li, “Study of frequency band gaps in metal-dielectric composite materials,” J. Phys. D 37, 1718–1724 ( 2004). [CrossRef]

19.

C. R. Simovski and S. A. Tretyakov, “Local constitutive parameters of metamaterials from an effective-medium perspective,” Phys. Rev. B 75, 195,111 ( 2007). [CrossRef]

20.

J. D. Jackson, Classical Electrodynamics (Wiley, New York, 1999).

21.

J. C. Maxwell-Garnett, Philos. Trans. R. Soc. London, Ser. A203, 385 ( 1904); 205, 237 ( 1906). [CrossRef]

22.

D. A. G. Bruggeman, “Calculation of various physics constants in heterogenous substances. Dielectricity constants and conductivity of mixed bodies from isotropic substances,” Ann. Phys. (Leipzig) 24, 636–664 ( 1935).

23.

M. F. MacMilland, R. P. Devaty, and J. V. Mantese, “Infrared properties of Pt/Al2O3 cermet films,” Phys. Rev. B 43, 13,838–13,845 ( 1991).

24.

R. Sainidou and F. J. García de Abajo, “Plasmon guided modes in nanoparticle metamaterials,” Opt. Express 16, 4499–4506 ( 2008). [CrossRef] [PubMed]

25.

D. J. Bergman, “Dielectric constant of a two-component granular composite: A practical scheme for calculating the pole spectrum,” Phys. Rev. B 19, 2359–2368 ( 1979). [CrossRef]

26.

P. Sheng, “Theory for the dielectric function of granular composite media,” Phys. Rev. Lett. 45, 60–63 ( 1980). [CrossRef]

27.

G. W. Milton, “Bounds and exact theories for the transport properties of inhomogeneous media,” Appl. Phys. A-Mater. Sci. Process. 26, 207–220 ( 1981). [CrossRef]

28.

R. Fuchs, R. G. Barrera, and J. L. Carrillo, “Spectral representations of the electron energy loss in composite media,” Phys. Rev. B 54, 12,824–12,834 ( 1996). [CrossRef]

29.

D. R. McKenzie and R. C. McPhedran, “Exact modeling of cubic lattice permittivity and conductivity,” Nature 265, 128–129 ( 1977). [CrossRef]

30.

R. C. McPhedran and D. R. McKenzie, “The conductivity of lattices of spheres. I. The simple cubic lattices,” Proc. R. Soc. London, Ser. A 359, 45–63 ( 1978). [CrossRef]

31.

D. R. McKenzie, R. C. McPhedran, and G. H. Derrick, “The conductivity of lattices of spheres. II. The body centred and face centred cubic lattices,” Proc. R. Soc. London, Ser. A 362, 211–232 ( 1978). [CrossRef]

32.

F. Wu and K. W. Whites, “Quasi-static effective permittivity of periodic composites containing complex shaped dielectric particles,” IEEE Trans. Antennas Propag. 49, 1174–1182 ( 2001). [CrossRef]

33.

K. W. Whites and F. Wu, “Effects of particle shape on the effective permittivity of composite materials with measurements for lattices of cubes,” IEEE Trans. Microw. Theory Tech. 50, 1723–1729 ( 2002). [CrossRef]

34.

S. B. Jones and S. P. Friedman, “Particle shape effects on the effective permittivity of anisotropic or isotropic media consisiting of aligned or randomly oriented ellipsoidal particles,” Water Resour. Res. 36, 2821–2833 ( 2000). [CrossRef]

35.

A. H. Sihvola and I. V. Lindell, “Chiral Maxwell-Garnett mixing formula,” Electron. Lett. 26, 118–119 ( 1990). [CrossRef]

36.

J. S. Ahn, K. H. Kim, T.W. Noh, D. H. Riu, K. H. Boo, and H. E. Kim, “Effective-medium theories for spheroidal particles randomly oriented on a plane: Application to the optical properties of a SiC whisker-Al2O3 composite,” Phys. Rev. B 52, 15,244–15,252 ( 1995).

37.

R. G. Barrera and R. Fuchs, “Theory of electron energy loss in a random system of spheres,” Phys. Rev. B 52, 3256–3273( 1995). [CrossRef]

38.

N. Stefanou, V. Yannopapas, and A. Modinos, Comput. Phys. Commun.113, 49 ( 1998); 132, 189 ( 2000). [CrossRef]

39.

N. Stefanou, V. Yannopapas, and A. Modinos, “MULTEM 2: A new version of the program for transmission and band-structure calculations of photonic crystals,” Comput. Phys. Commun. 132, 189–196 ( 2000). [CrossRef]

40.

S. Riikonen, I. Romero, and F. J. García de Abajo, “Plasmon tunability in metallodielectric metamaterials,” Phys. Rev. B 71, 235,104 ( 2005). [CrossRef]

41.

P. B. Johnson and R. W. Christy, “Optical constants of the noble metals,” Phys. Rev. B 6, 4370–4379 ( 1972). [CrossRef]

42.

E. D. Palik, Handbook of Optical Constants of Solids (Academic Press, New York, 1985).

43.

D. R. Smith, S. Schultz, P. Markos, and C. M. Soukoulis, “Determination of effective permittivity and permeability of metamaterials from reflection and transmission coefficients,” Phys. Rev. B 65, 195,104 ( 2002). [CrossRef]

44.

U. Kreibig and M. Vollmer, Optical Properties of Metal Clusters (Springer-Verlag, Berlin, 1995).

45.

F. J. García de Abajo, “Nonlocal effects in the plasmons of strongly interacting nanoparticles, dimers, and waveguides,” J. Phys. Chem. C 112, 17,983–17,987 ( 2008). [CrossRef]

46.

R. F. Egerton, Electron Energy-Loss Spectroscopy in the Electron Microscope (Plenum Press, New York, 1996).

47.

F. J. García de Abajo and A. Howie, “Relativistic electron energy loss and electron-induced photon emission in inhomogeneous dielectrics,” Phys. Rev. Lett. 80, 5180–5183 ( 1998). [CrossRef]

48.

F. J. García de Abajo and A. Howie, “Retarded field calculation of electron energy loss in inhomogeneous dielectrics,” Phys. Rev. B 65, 115,418 ( 2002). [CrossRef]

OCIS Codes
(240.6680) Optics at surfaces : Surface plasmons
(160.3918) Materials : Metamaterials
(160.4236) Materials : Nanomaterials

ToC Category:
Metamaterials

History
Original Manuscript: August 24, 2009
Revised Manuscript: October 16, 2009
Manuscript Accepted: November 4, 2009
Published: November 17, 2009

Citation
Isabel Romero and F. Javier García de Abajo, "Anisotropy and particle-size effects in nanostructured plasmonic metamaterials," Opt. Express 17, 22012-22022 (2009)
http://www.opticsinfobase.org/oe/abstract.cfm?URI=oe-17-24-22012


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References

  1. T. J. Yen, W. J. Padilla, N. Fang, D. C. Vier, D. R. Smith, J. B. Pendry, D. N. Basov, and X. Zhang, "Terahertz magnetic response from artificial materials," Science 303, 1494-1496 (2004). [CrossRef] [PubMed]
  2. D. R. Smith, J. B. Pendry, and M. C. K. Wiltshire, "Metamaterials and negative refractive index," Science 305, 788-792 (2004). [CrossRef] [PubMed]
  3. A. Boltasseva and V. M. Shalaev, "Fabrication of optical negative-index metamaterials: Recent advances and outlook," Metamaterials 2, 1-17 (2008). [CrossRef]
  4. J. B. Pendry, "Negative refraction makes a perfect lens," Phys. Rev. Lett. 85, 3966-3969 (2000). [CrossRef] [PubMed]
  5. J. B. Pendry, D. Schurig, and D. R. Smith, "Controlling electromagnetic fields," Science 312, 1780-1782 (2006). [CrossRef] [PubMed]
  6. D. Schurig, J. J. Mock, B. J. Justice, S. A. Cummer, J. B. Pendry, A. F. Starr, and D. R. Smith, "Metamaterial electromagnetic cloak at microwave frequencies," Science 314, 977-980 (2006). [CrossRef] [PubMed]
  7. W. S. Cai, U. K. Chettiar, A. V. Kildishev, and V. M. Shalaev, "Optical cloaking with metamaterials," Nat. Photonics 1, 224-227 (2007). [CrossRef]
  8. L. M. Liz-Marzan, "Tailoring surface plasmon through the morphology and assembly of metal nanoparticles," Langmuir 22, 32-41 (2006). [CrossRef]
  9. A. Taleb, V. Russier, A. Courty, and M. P. Pileni, "Collective optical properties of silver nanoparticles organized in two-dimensional superlattices," Phys. Rev. B 59, 13,350-13,358 (1999). [CrossRef]
  10. D. Zanchet, M. S. Moreno, and D. Ugarte, "Anomalous packing in thin nanoparticle supercrystals," Phys. Rev. Lett. 82, 5277-5280 (1999). [CrossRef]
  11. M. Gadenne, V. Podolskiy, P. Gadenne, P. Sheng, and V. M. Shalaev, "Plasmon-enhanced absorption by optical phonons in metal-dielectric composites," Europhys. Lett. 53, 364-370 (2001). [CrossRef]
  12. F. Caruso, M. Spasova, V. S. no Maceira, and L. M. Liz-Marzan, "Multilayer assemblies of silica-encapsulated gold nanoparticles on decomposable colloid templates," Adv. Mater. 13, 1090-1094 (2001). [CrossRef]
  13. T. Ung, L. M. Liz-Marzan, and P. Mulvaney, "Optical properties of thin films of Au@SiO2 particles," J. Phys. Chem. B 105, 3441-3452 (2001). [CrossRef]
  14. H. Fan, K. Yang, D. M. Boye, T. Sigmon, K. J. Malloy, H. Xu, G. P. Lopez, and C. J. Brinker, "Self-assymbly of ordered, robust, three-dimensional gold nanocrystal/silica arrays," Science 304, 567 (2004). [CrossRef] [PubMed]
  15. H. Contopanagos, C. A. Kyriazidou, W. M. Merrill, and N. G. Alexopoulos, "Effective response functions for photonic bandgap materials," J. Opt. Soc. Am. A 16, 1682-1699 (1999). [CrossRef]
  16. Z. Wang, C. T. Chan, W. Zhang, N. Ming, and P. Sheng, "Three-dimensional self -assembly of metal nanoparticles: Possible photonic crystal with a complete gap below the plasma frequency," Phys. Rev. B 64, 113,108 (2001). [CrossRef]
  17. A. A. Zakhidov, R. H. Baughman, I. I. Khayrullin, I. A. Udad, M. Kozlov, N. Eradat, V. Z. Vardeny, M. Sigalas, and R. Biswas, "Three-dimensionally periodic conductive nanostructures: network versus cermet topologies for metallic PGB," Synthetic Metals 116, 419-426 (2001). [CrossRef]
  18. P. Xu and Z. Li, "Study of frequency band gaps in metal-dielectric composite materials," J. Phys. D 37, 1718-1724 (2004). [CrossRef]
  19. C. R. Simovski and S. A. Tretyakov, "Local constitutive parameters of metamaterials from an effective-medium perspective," Phys. Rev. B 75, 195,111 (2007). [CrossRef]
  20. J. D. Jackson, Classical Electrodynamics (Wiley, New York, 1999).
  21. J. C. Maxwell-Garnett, Philos. Trans. R. Soc. London, Ser. A 203, 385 (1904); 205, 237 (1906). [CrossRef]
  22. D. A. G. Bruggeman, "Calculation of various physics constants in heterogenous substances. Dielectricity constants and conductivity of mixed bodies from isotropic substances," Ann. Phys. (Leipzig) 24, 636-664 (1935).
  23. M. F. MacMilland, R. P. Devaty, and J. V. Mantese, "Infrared properties of Pt/Al2O3 cermet films," Phys. Rev. B 43, 13,838-13,845 (1991).
  24. R. Sainidou and F. J. Garcıa de Abajo, "Plasmon guided modes in nanoparticle metamaterials," Opt. Express 16, 4499-4506 (2008). [CrossRef] [PubMed]
  25. D. J. Bergman, "Dielectric constant of a two-component granular composite: A practical scheme for calculating the pole spectrum," Phys. Rev. B 19, 2359-2368 (1979). [CrossRef]
  26. P. Sheng, "Theory for the dielectric function of granular composite media," Phys. Rev. Lett. 45, 60-63 (1980). [CrossRef]
  27. G. W. Milton, "Bounds and exact theories for the transport properties of inhomogeneous media," Appl. Phys. A-Mater. Sci. Process. 26, 207-220 (1981). [CrossRef]
  28. R. Fuchs, R. G. Barrera, and J. L. Carrillo, "Spectral representations of the electron energy loss in composite media," Phys. Rev. B 54, 12,824-12,834 (1996). [CrossRef]
  29. D. R. McKenzie and R. C. McPhedran, "Exact modeling of cubic lattice permittivity and conductivity," Nature 265, 128-129 (1977). [CrossRef]
  30. R. C. McPhedran and D. R. McKenzie, "The conductivity of lattices of spheres. I. The simple cubic lattices," Proc. R. Soc. London, Ser. A 359, 45-63 (1978). [CrossRef]
  31. D. R. McKenzie, R. C. McPhedran, and G. H. Derrick, "The conductivity of lattices of spheres. II. The body centred and face centred cubic lattices," Proc. R. Soc. London, Ser. A 362, 211-232 (1978). [CrossRef]
  32. F. Wu and K. W. Whites, "Quasi-static effective permittivity of periodic composites containing complex shaped dielectric particles," IEEE Trans. Antennas Propag. 49, 1174-1182 (2001). [CrossRef]
  33. K. W. Whites and F. Wu, "Effects of particle shape on the effective permittivity of composite materials with measurements for lattices of cubes," IEEE Trans. Microw. Theory Tech. 50, 1723-1729 (2002). [CrossRef]
  34. S. B. Jones and S. P. Friedman, "Particle shape effects on the effective permittivity of anisotropic or isotropic media consisiting of aligned or randomly oriented ellipsoidal particles," Water Resour. Res. 36, 2821-2833 (2000). [CrossRef]
  35. A. H. Sihvola and I. V. Lindell, "Chiral Maxwell-Garnett mixing formula," Electron. Lett. 26, 118-119 (1990). [CrossRef]
  36. J. S. Ahn, K. H. Kim, T. W. Noh, D. H. Riu, K. H. Boo, and H. E. Kim, "Effective-medium theories for spheroidal particles randomly oriented on a plane: Application to the optical properties of a SiC whisker-Al2O3 composite," Phys. Rev. B 52, 15,244-15,252 (1995).
  37. R. G. Barrera and R. Fuchs, "Theory of electron energy loss in a random system of spheres," Phys. Rev. B 52, 3256-3273 (1995). [CrossRef]
  38. N. Stefanou, V. Yannopapas, and A. Modinos, Comput. Phys. Commun. 113, 49 (1998); 132, 189 (2000). [CrossRef]
  39. N. Stefanou, V. Yannopapas, and A. Modinos, "MULTEM 2: A new version of the program for transmission and band-structure calculations of photonic crystals," Comput. Phys. Commun. 132, 189-196 (2000). [CrossRef]
  40. S. Riikonen, I. Romero, and F. J. Garcıa de Abajo, "Plasmon tunability in metallodielectric metamaterials," Phys. Rev. B 71, 235,104 (2005). [CrossRef]
  41. P. B. Johnson and R. W. Christy, "Optical constants of the noble metals," Phys. Rev. B 6, 4370-4379 (1972). [CrossRef]
  42. E. D. Palik, Handbook of Optical Constants of Solids (Academic Press, New York, 1985).
  43. D. R. Smith, S. Schultz, P. Markos, and C. M. Soukoulis, "Determination of effective permittivity and permeability of metamaterials from reflection and transmission coefficients," Phys. Rev. B 65, 195,104 (2002). [CrossRef]
  44. U. Kreibig and M. Vollmer, Optical Properties of Metal Clusters (Springer-Verlag, Berlin, 1995).
  45. F. J. Garcıa de Abajo, "Nonlocal effects in the plasmons of strongly interacting nanoparticles, dimers, and waveguides," J. Phys. Chem. C 112, 17,983-17,987 (2008). [CrossRef]
  46. R. F. Egerton, Electron Energy-Loss Spectroscopy in the Electron Microscope (Plenum Press, New York, 1996).
  47. F. J. Garcıa de Abajo and A. Howie, "Relativistic electron energy loss and electron-induced photon emission in inhomogeneous dielectrics," Phys. Rev. Lett. 80, 5180-5183 (1998). [CrossRef]
  48. F. J. Garcıa de Abajo and A. Howie, "Retarded field calculation of electron energy loss in inhomogeneous dielectrics," Phys. Rev. B 65, 115,418 (2002). [CrossRef]

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