Abstract

We investigate hybridized electric and magnetic plasmon modes in stacked nanocups. To elucidate the coupling mechanism we demonstrate the analogy between split-ring-resonators and nanocups in the case of dipolar excitation and compare the behavior of stacked nanocups to stacked split-ring-resonators. The interplay of electric coupling with the symmetric and antisymmetric coupling of magnetic moments in effective split-ring-resonator resonances in the nanocups leads to experimentally observed hybridized modes in the coupled nanocup system. Our stacked nanocups are easily manufacturable at low cost, they cover a large-area, and can serve as SERS or SEIRA substrates. They might also serve as novel plasmonic nanoantennas, as templates for nonlinear plasmonics, and as stacked meander surfaces for metamaterial-assisted imaging.

© 2012 OSA

1. Introduction

Goldcups and plasmonic core-shell systems [14] on the nanoscale gained a lot of attention due to the unique tunability of their spectral response [57] as well as their application as optical nanoantennas. Longitudinal and transverse modes have been studied in dependence of the light incident angle [810]. Nanocups as controllable SERS and SEIRA [11, 12] substrate as well as for medical applications have been demonstrated [13]. Additionally, nanocups hold great promise for nonlinear optical processes such as second harmonic generation [14, 15]. In view of the numerous applications the fabrication process is quite simple. It consists of evaporation steps onto chemically arranged polystyrene spheres [1619] and can be extended to a stacked nanocup system. Here, we demonstrate the possibility of coupling dipolar modes in this stacked nanocup arrangement and present a simple model based on the analogy of coupled magnetic split-ring-resonator resonances. This enables the understanding of the coupling mechanism in our system which was excited in a dipolar fashion. One intriguing aspect of the system is the fact that it is a combination of two well-known antenna concepts, namely spherical antennas as well as Yagi-Uda antennas [2022]. Spherical antennas feature the ability to concentrate electromagnetic light in their center [23], whereas a Yagi-Uda antennas possess true directivity. These two concepts can be combined by an arrangement of stacked nanocups, leading to a spherical Yagi-Uda antenna.

2. Results and discussion

In order to observe mode splitting [24] in stacked nanocups we fabricate the inner and outer cup separately and compare the results to the stacked structure, which is a combination of both structures (see schematic drawings Figs. 1a and 1b). To verify the coupling of the single cup systems we change their distance and investigate the dependence of the hybridized modes on the spacer thickness.

 

Fig. 1 (a) Schematic drawing of stacked nanocups (b) Geometrical parameters and thickness of the inner Au layer g1, MgF2 spacer layer d and outer Au layer g2 (c) hexagonally close-packed polystyrene sphere monolayer (d) FIB cut of the experimental realization of the coupled nanocups with parameters [g1, d, g2] = [27, 56, 29] nm (e) FIB cut of the inner cup based on an evaporated gold layer g1 = 27nm (f) FIB cut of the outer cup with additional magnesium fluoride layer and g2 = 25nm Au layer (deviation from (d) due to fabricational tolerances)

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Our sample fabrication is based on a hexagonally close-packed polystyrene sphere monolayer [1619] (see scanning electron microscope image in Fig. 1c). These spheres with diameter 1 μm are then coated with gold and magnesium fluoride layers by subsequent evaporation processes. The lift-off is performed by adhesive tape. A stripe of tape is placed on top of the last evaporated gold layer, carefully flattened with the fingertip, and subsequently removed from the glass slide. Thus, from this point on, the tape serves as the new substrate for the nanocups. The stacked structure can be regarded as a three layer system. The experimentally achieved parameters for this system are g1 = 27nm for the inner gold layer, d = 56nm for the magnesium fluoride spacer layer, and g2 = 29nm for the outer gold layer. The inner cup consists of a single 27 nm gold layer directly evaporated onto the polystyrene sphere, whereas the distance to the outer cup is maintained by using an additional magnesium fluoride layer, which also determines the diameter of the outer cup. We fabricated the stacked cup system as well as a single outer and inner cup and used focused ion beam (FIB) milling to examine the shape of these structures. Figure 1d shows that there is nice correspondence between design and experimental result of our stacked nanocups. Due to the fabrication process the cups do not have perfect spherical shape but are rather ellipsoids. This can also be see in the case of the single inner cup (see Fig. 1e) and the single outer cup system (see Fig. 1f). The images also prove that the shown single cups possess the corresponding geometrical parameters which fulfill the requirements of the components of the three layer system and make them suitable to analyze the coupling process.

2.1. Reflectance spectra

The spectral behavior of the fabricated structures is investigated by Fourier-transform infrared (FTIR) spectroscopy measurements, carried out with a Bruker Vertex 80 spectrometer extended by a Bruker Hyperion 2000 microscope, and compared to simulations performed by the FDTD Maxwell solver of CST Microwave Studio (CST AG, Darmstadt, Germany). Material parameters of gold are taken from experimental data [25]. The refractive index of polystyrene is assumend to be 1.58, for MgF2 we use a constant value of 1.38. The chosen parameters of spacer thickness and sphere diameter are consistent with the parameters that were measured using FIB cuts. We also take into account in the respective simulation that cups in our samples are not ideal spheres but rather ellipsoids. Only with this adaption the measured spectra can be reproduced.

The results are demonstrated in Fig. 2. Both in simulation and experiment a significant mode splitting is observable and the reflectance data show very good agreement. The sharp vibrational IR resonances at 52 THz and around 90 THz occur due to the presence of the polystyrene spheres. The interpretation of the spectroscopic data is based on the idea that the fabricated structures are deformed closed metallic films, which reflect all incoming light in the non-deformed case. Therefore, the interesting spectral features are the ones which differ most from the reflectance value R=1. Hence, the mode hybridization analysis is carried out at the dips in the reflectance spectra. In the case of the uncoupled single cup we find a reflectance dip at 80 THz in simulation and around 75 THz in the experiment for the outer cup. This is much lower than the dip frequency of the inner and smaller cup with a simulated value of 84 THz and measured value of 89 THz. When examining the coupled system we find two resonances at 56 THz and 85 THz in simulation and experimental values of 53 THz and 89 THz. In accordance to the mode hybridization theory [24] these values exceed the range spanned by the single cup resonances. Especially the lower resonance is shifted by more than 20 THz compared to the resonance of the single outer cup in simulation as well as in experiment. We will in the following discuss this in a detailed mode analysis in the framework of plasmon hybridization.

 

Fig. 2 Mode splitting in stacked nanocups: Comparison of reflectance spectra of the fabricated structures (Fig. 1) to simulated data. In analogy to the mode hybridization theory one additional reflectance dip appears for the stacked nanocup arrangement in simulation and experiment

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2.2. Mode hybridization analysis

In Fig. 3 we examine the electric charge distribution and magnetic field distribution at the observed resonance positions to characterize the involved modes. We plot the surface normal component of the electric field, which is proportional to the charge distribution (see Fig. 3b) and the y-component of the magnetic field (Fig. 3c). These illustrations are based on a normally incident plane wave with an electric field component in x-direction and magnetic field component in y-direction. Further investigation of the different modes shows that the observed single cup modes are dipolar in nature for both the separate inner and outer cup. Based on the case of dipolar excitation we model the nanocup mode in analogy to the fundamental mode of a split-ring-resonator [2628] oriented parallel to the incoming electric field component (Fig. 3a). In this case a magnetic moment oriented in y-direction becomes observable in the y-component of the magnetic field. Thus magnetic coupling in nanocups can be compared to coupled split-ring-resonators. On the basis of this model we observe in the stacked arrangement an antisymmetric mode arrangement for the lower resonance and a symmetric mode arrangement for the higher resonance, both for electric and magnetic cases.

 

Fig. 3 Mode classification for stacked nanocups. (a) Visualization of analogy to split-ring-resonator modes and identification of symmetric and antisymmetric mode. (b) Electric mode via charge distribution from CST Microwave Studio. (c) Magnetic mode via y-component of the magnetic field in order to visualize magnetic moment coupling from CST Microwave Studio.

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In the case of an antisymmetric mode arrangement we observe opposite electric field components for the inner and outer cup. The dipolar excitation of the outer cup is much smaller than the inner cup excitation and the scale for the outer cup in the graph is adapted to make the charge distribution visible. The opposed magnetic moments compensate each other and therefore no resulting magnetic moment in y-direction is visible. Therefore, both the electric and magnetic moments are arranged in the configuration leading to lowest energy, which is responsible for the strong redshift of this resonance compared to the resonances in the single cups. In the symmetric mode arrangement we observe parallel oriented electric field components for the inner and outer cup. Magnetic moments point in the same direction and generate a significant magnetic moment in y-direction.

As a consequence coupling in stacked nanocups can be reduced to symmetric and antisymmetric coupling of the effective split-ring-resonators [2932], as long as the excitation due to the incident light is dipolar.

2.3. Variation of spacer thickness

In order to examine the coupling mechanism in more detail, we display in Fig. 4 the spectral behavior of samples with a different thickness of the magnesium fluoride layer in simulation and experiment. The simulated dependence of shape and position of the resonances is in very good agreement with the experimental data. The depth of the lower frequency resonance declines with smaller spacer layers. In the experimental case its depth varies from 0.7 with a spacer layer of 36 nm and 0.7 (spacer layer of 46 nm) to 0.65 in the case of 56 nm spacer layer. In simulated results reflectance values of the lower resonance frequency vary from 0.68 in the case of the two smaller spacer layers and reach their maximum depth at 0.65. In other stacked arrangements one would expect a convergent behavior of both resonances with respect to the position of resonance frequencies when spacer layers are varied. In our case this is not so apparent due to the fact that the geometrical properties of the outer cup are strongly changed when using our illustrated fabrication method. In terms of stacked nanocups the position of the resonance frequencies shifts from 52 THz and 88 THz (spacer layer d = 36nm and d = 46nm) to 53 THz and 89 THz in the experimental case and from 55 THz and 84 THz, 55 THz and 85 THz to 56 THz and 85 THz in simulation. The dependence of resonance frequencies on spacer layer thickness is a strong indication for the suggested coupling mechanism.

 

Fig. 4 Variation of spacer thickness in stacked cups illustrated by three samples with parameters [g1, d1, g2] = [27, 56, 29] nm, [g1, d2, g2] = [27, 46, 29] nm, [g1, d3, g2] = [27, 36, 29] nm.

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3. Conclusion

In this article we showed a possibility to fabricate stacked nanocups and built up a model based on dipolar modes in split-ring-resonators to explain the coupling mechanism. Calculating the near-field distribution of the electric and magnetic fields of the structure verifies the predicted electric and magnetic coupling in effective split-ring-resonators. As a consequence we observed mode splitting in our reflectance data experimentally as well as in the simulated case. In addition to that we demonstrated the dependence of spacer layer thickness on the depth of the additionally occurring lower frequency dip and therefore the link to the coupling strength of the system.

Being a combination of the concepts of spherical and Yagi-Uda antennas, the special geometry of the obtained structure makes it suitable for antenna applications. Additionally, our new material might be well suited as tunable SERS or SEIRA [11, 12] substrate as well as for nonlinear plasmonic applications. The resonance positions are throughout the fingerprint region in the mid-IR, which makes them suitable for biological spectroscopy. Furthermore, they can be regarded as stacked metallic meanders that are suitable for sub-wavelength imaging applications [33, 34].

Acknowledgments

We acknowledge B. Fenk for the FIB cuts, M. Ubl for technical support, as well as DFG and Baden-Württemberg-Stiftung for funding. Publication was supported by the German Research Foundation within the funding program Open Access Publishing.

References and links

1. R. D. Averitt, D. Sarkar, and N. J. Halas, “Plasmon resonance shifts of Au-coated Au2S nanoshells: insight into multicomponent nanoparticle growth,” Phys. Rev. Lett. 78, 4217–4220 (1997). [CrossRef]  

2. S. J. Oldenburg, R. D. Averitt, S. L. Westcott, and N. J. Halas, “Nanoengineering of optical resonances,” Chem. Phys. Lett. 288, 243–247 (1998). [CrossRef]  

3. S. Mukherjee, H. Sobhani, J. B. Lassiter, R. Bardhan, P. Nordlander, and N. J. Halas, “Fanoshells: nanoparticles with built-in Fano resonances,” Nano Lett. 10, 2694–2701 (2010). [CrossRef]  

4. M. Cortie and M. Ford, “A plasmon-induced current loop in gold semi-shells,” Nanotechnology 18, 235704 (2007). [CrossRef]  

5. J. Ye, L. Lagae, G. Maes, G. Borghs, and P. Van Dorpe, “Symmetry breaking induced optical properties of gold open shell nanostructures,” Opt. Express 17, 23765–23771 (2009). [CrossRef]  

6. J. Ye, P. Van Dorpe, W. Van Roy, G. Borghs, and G. Maes, “Fabrication, characterization, and optical properties of gold nanobowl submonolayer structures,” Langmuir 25, 1822–1827 (2009). [CrossRef]  

7. J. Ye, N. Verellen, W. Van Roy, L. Lagae, G. Maes, G. Borghs, and P. Van Dorpe, “Plasmonic modes of metallic semishells in a polymer film,” ACS Nano 4, 1457–1464 (2010). [CrossRef]  

8. N. A. Mirin and N. J. Halas, “Light-bending nanoparticles,” Nano Lett. 9, 1255–1259 (2009). [CrossRef]  

9. N. S. King, Y. Li, C. Ayala-Orozco, T. Brannan, P. Nordlander, and N. J. Halas, “Angle- and spectral-dependent light scattering from plasmonic nanocups,” ACS Nano 5, 7254–7262 (2011). [CrossRef]  

10. P. Van Dorpe and J. Ye, “Semishells: versatile plasmonic nanoparticles,” ACS Nano 5, 6774–6778 (2011). [CrossRef]  

11. F. Neubrech, A. Pucci, T. W. Cornelius, S. Karim, A. Garcia-Etxarri, and J. Aizpurua, “Resonant plasmonic and vibrational coupling in a tailored nanoantenna for infrared detection,” Phys. Rev. Lett. 101, 157403 (2008). [CrossRef]  

12. C. Wu, A. B. Khanikaev, R. Adato, N. Arju, A. Ali Yanik, H. Altug, and G. Shvets, “Fano-resonant asymmetric metamaterials for ultrasensitive spectroscopy and identification of molecular monolayers,” Nat. Mater. 11, 69–75 (2012). [CrossRef]  

13. L. R. Hirsch, R. J. Stafford, J. A. Bankson, S. R. Sershen, B. Rivera, R. E. Price, J. D. Hazle, N. J. Halas, and J. L. West, “Nanoshell-mediated near-infrared thermal therapy of tumors under magnetic resonance guidance,” Proc. Natl. Acad. Sci. USA 100, 13549–13554 (2003). [CrossRef]  

14. Y. Zhang, N. K. Grady, C. Ayala-Orozco, and N. J. Halas, “Three-dimensional nanostructures as highly efficient generators of second harmonic light,” Nano Lett. 11, 5519–5523 (2011). [CrossRef]  

15. Y. Pu, R. Grange, C. Hsieh, and D. Psaltis, “Nonlinear optical properties of core-shell nanocavities for enhanced second-harmonic generation,” Phys. Rev. Lett. 104, 207402 (2010). [CrossRef]  

16. A. Kosiorek, W. Kandulski, H. Glaczynska, and M. Giersig, “Fabrication of nanoscale rings, dots, and rods by combining shadow nanosphere lithography and annealed polystyrene nanosphere masks,” Small 1, 439–444 (2005). [CrossRef]  

17. S. Yang, S. G. Jang, D. Choi, S. Kim, and H. K. Yu, “Nanomachining by colloidal lithography,” Small 2, 458–475 (2006). [CrossRef]  

18. M. C. Gwinner, E. Koroknay, L. Fu, P. Patoka, W. Kandulski, M. Giersig, and H. Giessen, “Periodic large-area metallic split-ring resonator metamaterial fabrication based on shadow nanosphere lithography,” Small 5, 400–406 (2009). [CrossRef]  

19. J. Zhao, B. Frank, S. Burger, and H. Giessen, “Large-area high-quality plasmonic oligomers fabricated by angle-controlled colloidal nanolithography,” ACS Nano 5, 9009–9016 (2011). [CrossRef]  

20. T. H. Taminiau, F. D. Stefani, and N. F. van Hulst, “Enhanced directional excitation and emission of single emitters by a nano-optical Yagi-Uda antenna,” Opt. Express 16, 10858–10866 (2008). [CrossRef]  

21. T. Pakizeh and M. Käll, “Unidirectional ultracompact optical nanoantennas,” Nano Lett. 9, 2343–2349 (2009). [CrossRef]  

22. D. Dregely, R. Taubert, J. Dorfmüller, R. Vogelgesang, K. Kern, and H. Giessen, “3D optical Yagi-Uda nanoantenna array,” Nat. Commun. 2, 267 (2011). [CrossRef]  

23. R. M. Cole, J. J. Baumberg, F. J. Garcia de Abajo, S. Mahajan, M. Abdelsalam, and P. N. Bartlett, “Understanding plasmons in nanoscale voids,” Nano Lett. 7, 2094–2100 (2007). [CrossRef]  

24. E. Prodan, C. Radloff, N. J. Halas, and P. Nordlander, “A hybridization model for the plasmon response of complex nanostructures,” Science 302, 419–422 (2003). [CrossRef]  

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

26. J. B. Pendry, A. J. Holden, D. J. Robbins, and W. J. Stewart, “Magnetism from conductors and enhanced nonlinear phenomena,” IEEE Trans. Microwave Theory Tech. 47, 2075–2084 (1999). [CrossRef]  

27. C. Rockstuhl, F. Lederer, C. Etrich, T. Zentgraf, J. Kuhl, and H. Giessen, “On the reinterpretation of resonances in split-ring-resonators at normal incidence,” Opt. Express 14, 8827–8836 (2006). [CrossRef]  

28. S. Linden, C. Enkrich, G. Dolling, M. W. Klein, J. Zhou, T. Koschny, C. M. Soukoulis, S. Burger, F. Schmidt, and M. Wegener, “Photonic metamaterials: magnetism at optical frequencies,” IEEE J. Sel. Top. Quantum Electron. 12, 1097–1105 (2006). [CrossRef]  

29. N. Liu, H. Liu, S. Zhu, and H. Giessen, “Stereometamaterials,” Nat. Photonics 3, 157–162 (2009). [CrossRef]  

30. N. Liu and H. Giessen, “Coupling effects in optical metamaterials,” Angew. Chem. Int. Ed. 49, 9838–9852 (2010). [CrossRef]  

31. H. Guo, N. Liu, L. Fu, T. P. Meyrath, T. Zentgraf, H. Schweizer, and H. Giessen, “Resonance hybridization in double split-ring resonator metamaterials,” Opt. Express 15, 12095–12101 (2007). [CrossRef]  

32. N. J. Halas, S. Lal, W. Chang, S. Link, and P. Nordlander, “Plasmons in strongly coupled metallic nanostructures,” Chem. Rev. 111, 3913–3961 (2011). [CrossRef]  

33. Ph. Schau, K. Frenner, L. Fu, H. Schweizer, H. Giessen, and W. Osten, “Design of highly transmissive metallic meander stacks with different grating periodicities for subwavelength-imaging applications,” Opt. Express 19, 3627–3636 (2011). [CrossRef]  

34. L. Fu, P. Schau, K. Frenner, H. Schweizer, J. Zhao, B. Frank, L. Wollet, P. Gaiser, B. Gompf, H. Giessen, and W. Osten, “Experimental demonstration of dispersion engineering through mode interactions in plasmonic microcavities,” Proc. SPIE 8423, 84232I (2012). [CrossRef]  

References

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  1. R. D. Averitt, D. Sarkar, and N. J. Halas, “Plasmon resonance shifts of Au-coated Au2S nanoshells: insight into multicomponent nanoparticle growth,” Phys. Rev. Lett.78, 4217–4220 (1997).
    [CrossRef]
  2. S. J. Oldenburg, R. D. Averitt, S. L. Westcott, and N. J. Halas, “Nanoengineering of optical resonances,” Chem. Phys. Lett.288, 243–247 (1998).
    [CrossRef]
  3. S. Mukherjee, H. Sobhani, J. B. Lassiter, R. Bardhan, P. Nordlander, and N. J. Halas, “Fanoshells: nanoparticles with built-in Fano resonances,” Nano Lett.10, 2694–2701 (2010).
    [CrossRef]
  4. M. Cortie and M. Ford, “A plasmon-induced current loop in gold semi-shells,” Nanotechnology18, 235704 (2007).
    [CrossRef]
  5. J. Ye, L. Lagae, G. Maes, G. Borghs, and P. Van Dorpe, “Symmetry breaking induced optical properties of gold open shell nanostructures,” Opt. Express17, 23765–23771 (2009).
    [CrossRef]
  6. J. Ye, P. Van Dorpe, W. Van Roy, G. Borghs, and G. Maes, “Fabrication, characterization, and optical properties of gold nanobowl submonolayer structures,” Langmuir25, 1822–1827 (2009).
    [CrossRef]
  7. J. Ye, N. Verellen, W. Van Roy, L. Lagae, G. Maes, G. Borghs, and P. Van Dorpe, “Plasmonic modes of metallic semishells in a polymer film,” ACS Nano4, 1457–1464 (2010).
    [CrossRef]
  8. N. A. Mirin and N. J. Halas, “Light-bending nanoparticles,” Nano Lett.9, 1255–1259 (2009).
    [CrossRef]
  9. N. S. King, Y. Li, C. Ayala-Orozco, T. Brannan, P. Nordlander, and N. J. Halas, “Angle- and spectral-dependent light scattering from plasmonic nanocups,” ACS Nano5, 7254–7262 (2011).
    [CrossRef]
  10. P. Van Dorpe and J. Ye, “Semishells: versatile plasmonic nanoparticles,” ACS Nano5, 6774–6778 (2011).
    [CrossRef]
  11. F. Neubrech, A. Pucci, T. W. Cornelius, S. Karim, A. Garcia-Etxarri, and J. Aizpurua, “Resonant plasmonic and vibrational coupling in a tailored nanoantenna for infrared detection,” Phys. Rev. Lett.101, 157403 (2008).
    [CrossRef]
  12. C. Wu, A. B. Khanikaev, R. Adato, N. Arju, A. Ali Yanik, H. Altug, and G. Shvets, “Fano-resonant asymmetric metamaterials for ultrasensitive spectroscopy and identification of molecular monolayers,” Nat. Mater.11, 69–75 (2012).
    [CrossRef]
  13. L. R. Hirsch, R. J. Stafford, J. A. Bankson, S. R. Sershen, B. Rivera, R. E. Price, J. D. Hazle, N. J. Halas, and J. L. West, “Nanoshell-mediated near-infrared thermal therapy of tumors under magnetic resonance guidance,” Proc. Natl. Acad. Sci. USA100, 13549–13554 (2003).
    [CrossRef]
  14. Y. Zhang, N. K. Grady, C. Ayala-Orozco, and N. J. Halas, “Three-dimensional nanostructures as highly efficient generators of second harmonic light,” Nano Lett.11, 5519–5523 (2011).
    [CrossRef]
  15. Y. Pu, R. Grange, C. Hsieh, and D. Psaltis, “Nonlinear optical properties of core-shell nanocavities for enhanced second-harmonic generation,” Phys. Rev. Lett.104, 207402 (2010).
    [CrossRef]
  16. A. Kosiorek, W. Kandulski, H. Glaczynska, and M. Giersig, “Fabrication of nanoscale rings, dots, and rods by combining shadow nanosphere lithography and annealed polystyrene nanosphere masks,” Small1, 439–444 (2005).
    [CrossRef]
  17. S. Yang, S. G. Jang, D. Choi, S. Kim, and H. K. Yu, “Nanomachining by colloidal lithography,” Small2, 458–475 (2006).
    [CrossRef]
  18. M. C. Gwinner, E. Koroknay, L. Fu, P. Patoka, W. Kandulski, M. Giersig, and H. Giessen, “Periodic large-area metallic split-ring resonator metamaterial fabrication based on shadow nanosphere lithography,” Small5, 400–406 (2009).
    [CrossRef]
  19. J. Zhao, B. Frank, S. Burger, and H. Giessen, “Large-area high-quality plasmonic oligomers fabricated by angle-controlled colloidal nanolithography,” ACS Nano5, 9009–9016 (2011).
    [CrossRef]
  20. T. H. Taminiau, F. D. Stefani, and N. F. van Hulst, “Enhanced directional excitation and emission of single emitters by a nano-optical Yagi-Uda antenna,” Opt. Express16, 10858–10866 (2008).
    [CrossRef]
  21. T. Pakizeh and M. Käll, “Unidirectional ultracompact optical nanoantennas,” Nano Lett.9, 2343–2349 (2009).
    [CrossRef]
  22. D. Dregely, R. Taubert, J. Dorfmüller, R. Vogelgesang, K. Kern, and H. Giessen, “3D optical Yagi-Uda nanoantenna array,” Nat. Commun.2, 267 (2011).
    [CrossRef]
  23. R. M. Cole, J. J. Baumberg, F. J. Garcia de Abajo, S. Mahajan, M. Abdelsalam, and P. N. Bartlett, “Understanding plasmons in nanoscale voids,” Nano Lett.7, 2094–2100 (2007).
    [CrossRef]
  24. E. Prodan, C. Radloff, N. J. Halas, and P. Nordlander, “A hybridization model for the plasmon response of complex nanostructures,” Science302, 419–422 (2003).
    [CrossRef]
  25. P. B. Johnson and R. W. Christy, “Optical constants of the noble metals,” Phys. Rev. B6, 4370–4379 (1972).
    [CrossRef]
  26. J. B. Pendry, A. J. Holden, D. J. Robbins, and W. J. Stewart, “Magnetism from conductors and enhanced nonlinear phenomena,” IEEE Trans. Microwave Theory Tech.47, 2075–2084 (1999).
    [CrossRef]
  27. C. Rockstuhl, F. Lederer, C. Etrich, T. Zentgraf, J. Kuhl, and H. Giessen, “On the reinterpretation of resonances in split-ring-resonators at normal incidence,” Opt. Express14, 8827–8836 (2006).
    [CrossRef]
  28. S. Linden, C. Enkrich, G. Dolling, M. W. Klein, J. Zhou, T. Koschny, C. M. Soukoulis, S. Burger, F. Schmidt, and M. Wegener, “Photonic metamaterials: magnetism at optical frequencies,” IEEE J. Sel. Top. Quantum Electron.12, 1097–1105 (2006).
    [CrossRef]
  29. N. Liu, H. Liu, S. Zhu, and H. Giessen, “Stereometamaterials,” Nat. Photonics3, 157–162 (2009).
    [CrossRef]
  30. N. Liu and H. Giessen, “Coupling effects in optical metamaterials,” Angew. Chem. Int. Ed.49, 9838–9852 (2010).
    [CrossRef]
  31. H. Guo, N. Liu, L. Fu, T. P. Meyrath, T. Zentgraf, H. Schweizer, and H. Giessen, “Resonance hybridization in double split-ring resonator metamaterials,” Opt. Express15, 12095–12101 (2007).
    [CrossRef]
  32. N. J. Halas, S. Lal, W. Chang, S. Link, and P. Nordlander, “Plasmons in strongly coupled metallic nanostructures,” Chem. Rev.111, 3913–3961 (2011).
    [CrossRef]
  33. Ph. Schau, K. Frenner, L. Fu, H. Schweizer, H. Giessen, and W. Osten, “Design of highly transmissive metallic meander stacks with different grating periodicities for subwavelength-imaging applications,” Opt. Express19, 3627–3636 (2011).
    [CrossRef]
  34. L. Fu, P. Schau, K. Frenner, H. Schweizer, J. Zhao, B. Frank, L. Wollet, P. Gaiser, B. Gompf, H. Giessen, and W. Osten, “Experimental demonstration of dispersion engineering through mode interactions in plasmonic microcavities,” Proc. SPIE8423, 84232I (2012).
    [CrossRef]

2012

C. Wu, A. B. Khanikaev, R. Adato, N. Arju, A. Ali Yanik, H. Altug, and G. Shvets, “Fano-resonant asymmetric metamaterials for ultrasensitive spectroscopy and identification of molecular monolayers,” Nat. Mater.11, 69–75 (2012).
[CrossRef]

L. Fu, P. Schau, K. Frenner, H. Schweizer, J. Zhao, B. Frank, L. Wollet, P. Gaiser, B. Gompf, H. Giessen, and W. Osten, “Experimental demonstration of dispersion engineering through mode interactions in plasmonic microcavities,” Proc. SPIE8423, 84232I (2012).
[CrossRef]

2011

N. J. Halas, S. Lal, W. Chang, S. Link, and P. Nordlander, “Plasmons in strongly coupled metallic nanostructures,” Chem. Rev.111, 3913–3961 (2011).
[CrossRef]

Ph. Schau, K. Frenner, L. Fu, H. Schweizer, H. Giessen, and W. Osten, “Design of highly transmissive metallic meander stacks with different grating periodicities for subwavelength-imaging applications,” Opt. Express19, 3627–3636 (2011).
[CrossRef]

D. Dregely, R. Taubert, J. Dorfmüller, R. Vogelgesang, K. Kern, and H. Giessen, “3D optical Yagi-Uda nanoantenna array,” Nat. Commun.2, 267 (2011).
[CrossRef]

Y. Zhang, N. K. Grady, C. Ayala-Orozco, and N. J. Halas, “Three-dimensional nanostructures as highly efficient generators of second harmonic light,” Nano Lett.11, 5519–5523 (2011).
[CrossRef]

N. S. King, Y. Li, C. Ayala-Orozco, T. Brannan, P. Nordlander, and N. J. Halas, “Angle- and spectral-dependent light scattering from plasmonic nanocups,” ACS Nano5, 7254–7262 (2011).
[CrossRef]

P. Van Dorpe and J. Ye, “Semishells: versatile plasmonic nanoparticles,” ACS Nano5, 6774–6778 (2011).
[CrossRef]

J. Zhao, B. Frank, S. Burger, and H. Giessen, “Large-area high-quality plasmonic oligomers fabricated by angle-controlled colloidal nanolithography,” ACS Nano5, 9009–9016 (2011).
[CrossRef]

2010

S. Mukherjee, H. Sobhani, J. B. Lassiter, R. Bardhan, P. Nordlander, and N. J. Halas, “Fanoshells: nanoparticles with built-in Fano resonances,” Nano Lett.10, 2694–2701 (2010).
[CrossRef]

J. Ye, N. Verellen, W. Van Roy, L. Lagae, G. Maes, G. Borghs, and P. Van Dorpe, “Plasmonic modes of metallic semishells in a polymer film,” ACS Nano4, 1457–1464 (2010).
[CrossRef]

Y. Pu, R. Grange, C. Hsieh, and D. Psaltis, “Nonlinear optical properties of core-shell nanocavities for enhanced second-harmonic generation,” Phys. Rev. Lett.104, 207402 (2010).
[CrossRef]

N. Liu and H. Giessen, “Coupling effects in optical metamaterials,” Angew. Chem. Int. Ed.49, 9838–9852 (2010).
[CrossRef]

2009

J. Ye, L. Lagae, G. Maes, G. Borghs, and P. Van Dorpe, “Symmetry breaking induced optical properties of gold open shell nanostructures,” Opt. Express17, 23765–23771 (2009).
[CrossRef]

T. Pakizeh and M. Käll, “Unidirectional ultracompact optical nanoantennas,” Nano Lett.9, 2343–2349 (2009).
[CrossRef]

N. Liu, H. Liu, S. Zhu, and H. Giessen, “Stereometamaterials,” Nat. Photonics3, 157–162 (2009).
[CrossRef]

N. A. Mirin and N. J. Halas, “Light-bending nanoparticles,” Nano Lett.9, 1255–1259 (2009).
[CrossRef]

M. C. Gwinner, E. Koroknay, L. Fu, P. Patoka, W. Kandulski, M. Giersig, and H. Giessen, “Periodic large-area metallic split-ring resonator metamaterial fabrication based on shadow nanosphere lithography,” Small5, 400–406 (2009).
[CrossRef]

J. Ye, P. Van Dorpe, W. Van Roy, G. Borghs, and G. Maes, “Fabrication, characterization, and optical properties of gold nanobowl submonolayer structures,” Langmuir25, 1822–1827 (2009).
[CrossRef]

2008

F. Neubrech, A. Pucci, T. W. Cornelius, S. Karim, A. Garcia-Etxarri, and J. Aizpurua, “Resonant plasmonic and vibrational coupling in a tailored nanoantenna for infrared detection,” Phys. Rev. Lett.101, 157403 (2008).
[CrossRef]

T. H. Taminiau, F. D. Stefani, and N. F. van Hulst, “Enhanced directional excitation and emission of single emitters by a nano-optical Yagi-Uda antenna,” Opt. Express16, 10858–10866 (2008).
[CrossRef]

2007

H. Guo, N. Liu, L. Fu, T. P. Meyrath, T. Zentgraf, H. Schweizer, and H. Giessen, “Resonance hybridization in double split-ring resonator metamaterials,” Opt. Express15, 12095–12101 (2007).
[CrossRef]

R. M. Cole, J. J. Baumberg, F. J. Garcia de Abajo, S. Mahajan, M. Abdelsalam, and P. N. Bartlett, “Understanding plasmons in nanoscale voids,” Nano Lett.7, 2094–2100 (2007).
[CrossRef]

M. Cortie and M. Ford, “A plasmon-induced current loop in gold semi-shells,” Nanotechnology18, 235704 (2007).
[CrossRef]

2006

S. Yang, S. G. Jang, D. Choi, S. Kim, and H. K. Yu, “Nanomachining by colloidal lithography,” Small2, 458–475 (2006).
[CrossRef]

S. Linden, C. Enkrich, G. Dolling, M. W. Klein, J. Zhou, T. Koschny, C. M. Soukoulis, S. Burger, F. Schmidt, and M. Wegener, “Photonic metamaterials: magnetism at optical frequencies,” IEEE J. Sel. Top. Quantum Electron.12, 1097–1105 (2006).
[CrossRef]

C. Rockstuhl, F. Lederer, C. Etrich, T. Zentgraf, J. Kuhl, and H. Giessen, “On the reinterpretation of resonances in split-ring-resonators at normal incidence,” Opt. Express14, 8827–8836 (2006).
[CrossRef]

2005

A. Kosiorek, W. Kandulski, H. Glaczynska, and M. Giersig, “Fabrication of nanoscale rings, dots, and rods by combining shadow nanosphere lithography and annealed polystyrene nanosphere masks,” Small1, 439–444 (2005).
[CrossRef]

2003

L. R. Hirsch, R. J. Stafford, J. A. Bankson, S. R. Sershen, B. Rivera, R. E. Price, J. D. Hazle, N. J. Halas, and J. L. West, “Nanoshell-mediated near-infrared thermal therapy of tumors under magnetic resonance guidance,” Proc. Natl. Acad. Sci. USA100, 13549–13554 (2003).
[CrossRef]

E. Prodan, C. Radloff, N. J. Halas, and P. Nordlander, “A hybridization model for the plasmon response of complex nanostructures,” Science302, 419–422 (2003).
[CrossRef]

1999

J. B. Pendry, A. J. Holden, D. J. Robbins, and W. J. Stewart, “Magnetism from conductors and enhanced nonlinear phenomena,” IEEE Trans. Microwave Theory Tech.47, 2075–2084 (1999).
[CrossRef]

1998

S. J. Oldenburg, R. D. Averitt, S. L. Westcott, and N. J. Halas, “Nanoengineering of optical resonances,” Chem. Phys. Lett.288, 243–247 (1998).
[CrossRef]

1997

R. D. Averitt, D. Sarkar, and N. J. Halas, “Plasmon resonance shifts of Au-coated Au2S nanoshells: insight into multicomponent nanoparticle growth,” Phys. Rev. Lett.78, 4217–4220 (1997).
[CrossRef]

1972

P. B. Johnson and R. W. Christy, “Optical constants of the noble metals,” Phys. Rev. B6, 4370–4379 (1972).
[CrossRef]

Abdelsalam, M.

R. M. Cole, J. J. Baumberg, F. J. Garcia de Abajo, S. Mahajan, M. Abdelsalam, and P. N. Bartlett, “Understanding plasmons in nanoscale voids,” Nano Lett.7, 2094–2100 (2007).
[CrossRef]

Adato, R.

C. Wu, A. B. Khanikaev, R. Adato, N. Arju, A. Ali Yanik, H. Altug, and G. Shvets, “Fano-resonant asymmetric metamaterials for ultrasensitive spectroscopy and identification of molecular monolayers,” Nat. Mater.11, 69–75 (2012).
[CrossRef]

Aizpurua, J.

F. Neubrech, A. Pucci, T. W. Cornelius, S. Karim, A. Garcia-Etxarri, and J. Aizpurua, “Resonant plasmonic and vibrational coupling in a tailored nanoantenna for infrared detection,” Phys. Rev. Lett.101, 157403 (2008).
[CrossRef]

Ali Yanik, A.

C. Wu, A. B. Khanikaev, R. Adato, N. Arju, A. Ali Yanik, H. Altug, and G. Shvets, “Fano-resonant asymmetric metamaterials for ultrasensitive spectroscopy and identification of molecular monolayers,” Nat. Mater.11, 69–75 (2012).
[CrossRef]

Altug, H.

C. Wu, A. B. Khanikaev, R. Adato, N. Arju, A. Ali Yanik, H. Altug, and G. Shvets, “Fano-resonant asymmetric metamaterials for ultrasensitive spectroscopy and identification of molecular monolayers,” Nat. Mater.11, 69–75 (2012).
[CrossRef]

Arju, N.

C. Wu, A. B. Khanikaev, R. Adato, N. Arju, A. Ali Yanik, H. Altug, and G. Shvets, “Fano-resonant asymmetric metamaterials for ultrasensitive spectroscopy and identification of molecular monolayers,” Nat. Mater.11, 69–75 (2012).
[CrossRef]

Averitt, R. D.

S. J. Oldenburg, R. D. Averitt, S. L. Westcott, and N. J. Halas, “Nanoengineering of optical resonances,” Chem. Phys. Lett.288, 243–247 (1998).
[CrossRef]

R. D. Averitt, D. Sarkar, and N. J. Halas, “Plasmon resonance shifts of Au-coated Au2S nanoshells: insight into multicomponent nanoparticle growth,” Phys. Rev. Lett.78, 4217–4220 (1997).
[CrossRef]

Ayala-Orozco, C.

N. S. King, Y. Li, C. Ayala-Orozco, T. Brannan, P. Nordlander, and N. J. Halas, “Angle- and spectral-dependent light scattering from plasmonic nanocups,” ACS Nano5, 7254–7262 (2011).
[CrossRef]

Y. Zhang, N. K. Grady, C. Ayala-Orozco, and N. J. Halas, “Three-dimensional nanostructures as highly efficient generators of second harmonic light,” Nano Lett.11, 5519–5523 (2011).
[CrossRef]

Bankson, J. A.

L. R. Hirsch, R. J. Stafford, J. A. Bankson, S. R. Sershen, B. Rivera, R. E. Price, J. D. Hazle, N. J. Halas, and J. L. West, “Nanoshell-mediated near-infrared thermal therapy of tumors under magnetic resonance guidance,” Proc. Natl. Acad. Sci. USA100, 13549–13554 (2003).
[CrossRef]

Bardhan, R.

S. Mukherjee, H. Sobhani, J. B. Lassiter, R. Bardhan, P. Nordlander, and N. J. Halas, “Fanoshells: nanoparticles with built-in Fano resonances,” Nano Lett.10, 2694–2701 (2010).
[CrossRef]

Bartlett, P. N.

R. M. Cole, J. J. Baumberg, F. J. Garcia de Abajo, S. Mahajan, M. Abdelsalam, and P. N. Bartlett, “Understanding plasmons in nanoscale voids,” Nano Lett.7, 2094–2100 (2007).
[CrossRef]

Baumberg, J. J.

R. M. Cole, J. J. Baumberg, F. J. Garcia de Abajo, S. Mahajan, M. Abdelsalam, and P. N. Bartlett, “Understanding plasmons in nanoscale voids,” Nano Lett.7, 2094–2100 (2007).
[CrossRef]

Borghs, G.

J. Ye, N. Verellen, W. Van Roy, L. Lagae, G. Maes, G. Borghs, and P. Van Dorpe, “Plasmonic modes of metallic semishells in a polymer film,” ACS Nano4, 1457–1464 (2010).
[CrossRef]

J. Ye, P. Van Dorpe, W. Van Roy, G. Borghs, and G. Maes, “Fabrication, characterization, and optical properties of gold nanobowl submonolayer structures,” Langmuir25, 1822–1827 (2009).
[CrossRef]

J. Ye, L. Lagae, G. Maes, G. Borghs, and P. Van Dorpe, “Symmetry breaking induced optical properties of gold open shell nanostructures,” Opt. Express17, 23765–23771 (2009).
[CrossRef]

Brannan, T.

N. S. King, Y. Li, C. Ayala-Orozco, T. Brannan, P. Nordlander, and N. J. Halas, “Angle- and spectral-dependent light scattering from plasmonic nanocups,” ACS Nano5, 7254–7262 (2011).
[CrossRef]

Burger, S.

J. Zhao, B. Frank, S. Burger, and H. Giessen, “Large-area high-quality plasmonic oligomers fabricated by angle-controlled colloidal nanolithography,” ACS Nano5, 9009–9016 (2011).
[CrossRef]

S. Linden, C. Enkrich, G. Dolling, M. W. Klein, J. Zhou, T. Koschny, C. M. Soukoulis, S. Burger, F. Schmidt, and M. Wegener, “Photonic metamaterials: magnetism at optical frequencies,” IEEE J. Sel. Top. Quantum Electron.12, 1097–1105 (2006).
[CrossRef]

Chang, W.

N. J. Halas, S. Lal, W. Chang, S. Link, and P. Nordlander, “Plasmons in strongly coupled metallic nanostructures,” Chem. Rev.111, 3913–3961 (2011).
[CrossRef]

Choi, D.

S. Yang, S. G. Jang, D. Choi, S. Kim, and H. K. Yu, “Nanomachining by colloidal lithography,” Small2, 458–475 (2006).
[CrossRef]

Christy, R. W.

P. B. Johnson and R. W. Christy, “Optical constants of the noble metals,” Phys. Rev. B6, 4370–4379 (1972).
[CrossRef]

Cole, R. M.

R. M. Cole, J. J. Baumberg, F. J. Garcia de Abajo, S. Mahajan, M. Abdelsalam, and P. N. Bartlett, “Understanding plasmons in nanoscale voids,” Nano Lett.7, 2094–2100 (2007).
[CrossRef]

Cornelius, T. W.

F. Neubrech, A. Pucci, T. W. Cornelius, S. Karim, A. Garcia-Etxarri, and J. Aizpurua, “Resonant plasmonic and vibrational coupling in a tailored nanoantenna for infrared detection,” Phys. Rev. Lett.101, 157403 (2008).
[CrossRef]

Cortie, M.

M. Cortie and M. Ford, “A plasmon-induced current loop in gold semi-shells,” Nanotechnology18, 235704 (2007).
[CrossRef]

Dolling, G.

S. Linden, C. Enkrich, G. Dolling, M. W. Klein, J. Zhou, T. Koschny, C. M. Soukoulis, S. Burger, F. Schmidt, and M. Wegener, “Photonic metamaterials: magnetism at optical frequencies,” IEEE J. Sel. Top. Quantum Electron.12, 1097–1105 (2006).
[CrossRef]

Dorfmüller, J.

D. Dregely, R. Taubert, J. Dorfmüller, R. Vogelgesang, K. Kern, and H. Giessen, “3D optical Yagi-Uda nanoantenna array,” Nat. Commun.2, 267 (2011).
[CrossRef]

Dregely, D.

D. Dregely, R. Taubert, J. Dorfmüller, R. Vogelgesang, K. Kern, and H. Giessen, “3D optical Yagi-Uda nanoantenna array,” Nat. Commun.2, 267 (2011).
[CrossRef]

Enkrich, C.

S. Linden, C. Enkrich, G. Dolling, M. W. Klein, J. Zhou, T. Koschny, C. M. Soukoulis, S. Burger, F. Schmidt, and M. Wegener, “Photonic metamaterials: magnetism at optical frequencies,” IEEE J. Sel. Top. Quantum Electron.12, 1097–1105 (2006).
[CrossRef]

Etrich, C.

Ford, M.

M. Cortie and M. Ford, “A plasmon-induced current loop in gold semi-shells,” Nanotechnology18, 235704 (2007).
[CrossRef]

Frank, B.

L. Fu, P. Schau, K. Frenner, H. Schweizer, J. Zhao, B. Frank, L. Wollet, P. Gaiser, B. Gompf, H. Giessen, and W. Osten, “Experimental demonstration of dispersion engineering through mode interactions in plasmonic microcavities,” Proc. SPIE8423, 84232I (2012).
[CrossRef]

J. Zhao, B. Frank, S. Burger, and H. Giessen, “Large-area high-quality plasmonic oligomers fabricated by angle-controlled colloidal nanolithography,” ACS Nano5, 9009–9016 (2011).
[CrossRef]

Frenner, K.

L. Fu, P. Schau, K. Frenner, H. Schweizer, J. Zhao, B. Frank, L. Wollet, P. Gaiser, B. Gompf, H. Giessen, and W. Osten, “Experimental demonstration of dispersion engineering through mode interactions in plasmonic microcavities,” Proc. SPIE8423, 84232I (2012).
[CrossRef]

Ph. Schau, K. Frenner, L. Fu, H. Schweizer, H. Giessen, and W. Osten, “Design of highly transmissive metallic meander stacks with different grating periodicities for subwavelength-imaging applications,” Opt. Express19, 3627–3636 (2011).
[CrossRef]

Fu, L.

L. Fu, P. Schau, K. Frenner, H. Schweizer, J. Zhao, B. Frank, L. Wollet, P. Gaiser, B. Gompf, H. Giessen, and W. Osten, “Experimental demonstration of dispersion engineering through mode interactions in plasmonic microcavities,” Proc. SPIE8423, 84232I (2012).
[CrossRef]

Ph. Schau, K. Frenner, L. Fu, H. Schweizer, H. Giessen, and W. Osten, “Design of highly transmissive metallic meander stacks with different grating periodicities for subwavelength-imaging applications,” Opt. Express19, 3627–3636 (2011).
[CrossRef]

M. C. Gwinner, E. Koroknay, L. Fu, P. Patoka, W. Kandulski, M. Giersig, and H. Giessen, “Periodic large-area metallic split-ring resonator metamaterial fabrication based on shadow nanosphere lithography,” Small5, 400–406 (2009).
[CrossRef]

H. Guo, N. Liu, L. Fu, T. P. Meyrath, T. Zentgraf, H. Schweizer, and H. Giessen, “Resonance hybridization in double split-ring resonator metamaterials,” Opt. Express15, 12095–12101 (2007).
[CrossRef]

Gaiser, P.

L. Fu, P. Schau, K. Frenner, H. Schweizer, J. Zhao, B. Frank, L. Wollet, P. Gaiser, B. Gompf, H. Giessen, and W. Osten, “Experimental demonstration of dispersion engineering through mode interactions in plasmonic microcavities,” Proc. SPIE8423, 84232I (2012).
[CrossRef]

Garcia de Abajo, F. J.

R. M. Cole, J. J. Baumberg, F. J. Garcia de Abajo, S. Mahajan, M. Abdelsalam, and P. N. Bartlett, “Understanding plasmons in nanoscale voids,” Nano Lett.7, 2094–2100 (2007).
[CrossRef]

Garcia-Etxarri, A.

F. Neubrech, A. Pucci, T. W. Cornelius, S. Karim, A. Garcia-Etxarri, and J. Aizpurua, “Resonant plasmonic and vibrational coupling in a tailored nanoantenna for infrared detection,” Phys. Rev. Lett.101, 157403 (2008).
[CrossRef]

Giersig, M.

M. C. Gwinner, E. Koroknay, L. Fu, P. Patoka, W. Kandulski, M. Giersig, and H. Giessen, “Periodic large-area metallic split-ring resonator metamaterial fabrication based on shadow nanosphere lithography,” Small5, 400–406 (2009).
[CrossRef]

A. Kosiorek, W. Kandulski, H. Glaczynska, and M. Giersig, “Fabrication of nanoscale rings, dots, and rods by combining shadow nanosphere lithography and annealed polystyrene nanosphere masks,” Small1, 439–444 (2005).
[CrossRef]

Giessen, H.

L. Fu, P. Schau, K. Frenner, H. Schweizer, J. Zhao, B. Frank, L. Wollet, P. Gaiser, B. Gompf, H. Giessen, and W. Osten, “Experimental demonstration of dispersion engineering through mode interactions in plasmonic microcavities,” Proc. SPIE8423, 84232I (2012).
[CrossRef]

J. Zhao, B. Frank, S. Burger, and H. Giessen, “Large-area high-quality plasmonic oligomers fabricated by angle-controlled colloidal nanolithography,” ACS Nano5, 9009–9016 (2011).
[CrossRef]

D. Dregely, R. Taubert, J. Dorfmüller, R. Vogelgesang, K. Kern, and H. Giessen, “3D optical Yagi-Uda nanoantenna array,” Nat. Commun.2, 267 (2011).
[CrossRef]

Ph. Schau, K. Frenner, L. Fu, H. Schweizer, H. Giessen, and W. Osten, “Design of highly transmissive metallic meander stacks with different grating periodicities for subwavelength-imaging applications,” Opt. Express19, 3627–3636 (2011).
[CrossRef]

N. Liu and H. Giessen, “Coupling effects in optical metamaterials,” Angew. Chem. Int. Ed.49, 9838–9852 (2010).
[CrossRef]

M. C. Gwinner, E. Koroknay, L. Fu, P. Patoka, W. Kandulski, M. Giersig, and H. Giessen, “Periodic large-area metallic split-ring resonator metamaterial fabrication based on shadow nanosphere lithography,” Small5, 400–406 (2009).
[CrossRef]

N. Liu, H. Liu, S. Zhu, and H. Giessen, “Stereometamaterials,” Nat. Photonics3, 157–162 (2009).
[CrossRef]

H. Guo, N. Liu, L. Fu, T. P. Meyrath, T. Zentgraf, H. Schweizer, and H. Giessen, “Resonance hybridization in double split-ring resonator metamaterials,” Opt. Express15, 12095–12101 (2007).
[CrossRef]

C. Rockstuhl, F. Lederer, C. Etrich, T. Zentgraf, J. Kuhl, and H. Giessen, “On the reinterpretation of resonances in split-ring-resonators at normal incidence,” Opt. Express14, 8827–8836 (2006).
[CrossRef]

Glaczynska, H.

A. Kosiorek, W. Kandulski, H. Glaczynska, and M. Giersig, “Fabrication of nanoscale rings, dots, and rods by combining shadow nanosphere lithography and annealed polystyrene nanosphere masks,” Small1, 439–444 (2005).
[CrossRef]

Gompf, B.

L. Fu, P. Schau, K. Frenner, H. Schweizer, J. Zhao, B. Frank, L. Wollet, P. Gaiser, B. Gompf, H. Giessen, and W. Osten, “Experimental demonstration of dispersion engineering through mode interactions in plasmonic microcavities,” Proc. SPIE8423, 84232I (2012).
[CrossRef]

Grady, N. K.

Y. Zhang, N. K. Grady, C. Ayala-Orozco, and N. J. Halas, “Three-dimensional nanostructures as highly efficient generators of second harmonic light,” Nano Lett.11, 5519–5523 (2011).
[CrossRef]

Grange, R.

Y. Pu, R. Grange, C. Hsieh, and D. Psaltis, “Nonlinear optical properties of core-shell nanocavities for enhanced second-harmonic generation,” Phys. Rev. Lett.104, 207402 (2010).
[CrossRef]

Guo, H.

Gwinner, M. C.

M. C. Gwinner, E. Koroknay, L. Fu, P. Patoka, W. Kandulski, M. Giersig, and H. Giessen, “Periodic large-area metallic split-ring resonator metamaterial fabrication based on shadow nanosphere lithography,” Small5, 400–406 (2009).
[CrossRef]

Halas, N. J.

N. S. King, Y. Li, C. Ayala-Orozco, T. Brannan, P. Nordlander, and N. J. Halas, “Angle- and spectral-dependent light scattering from plasmonic nanocups,” ACS Nano5, 7254–7262 (2011).
[CrossRef]

N. J. Halas, S. Lal, W. Chang, S. Link, and P. Nordlander, “Plasmons in strongly coupled metallic nanostructures,” Chem. Rev.111, 3913–3961 (2011).
[CrossRef]

Y. Zhang, N. K. Grady, C. Ayala-Orozco, and N. J. Halas, “Three-dimensional nanostructures as highly efficient generators of second harmonic light,” Nano Lett.11, 5519–5523 (2011).
[CrossRef]

S. Mukherjee, H. Sobhani, J. B. Lassiter, R. Bardhan, P. Nordlander, and N. J. Halas, “Fanoshells: nanoparticles with built-in Fano resonances,” Nano Lett.10, 2694–2701 (2010).
[CrossRef]

N. A. Mirin and N. J. Halas, “Light-bending nanoparticles,” Nano Lett.9, 1255–1259 (2009).
[CrossRef]

L. R. Hirsch, R. J. Stafford, J. A. Bankson, S. R. Sershen, B. Rivera, R. E. Price, J. D. Hazle, N. J. Halas, and J. L. West, “Nanoshell-mediated near-infrared thermal therapy of tumors under magnetic resonance guidance,” Proc. Natl. Acad. Sci. USA100, 13549–13554 (2003).
[CrossRef]

E. Prodan, C. Radloff, N. J. Halas, and P. Nordlander, “A hybridization model for the plasmon response of complex nanostructures,” Science302, 419–422 (2003).
[CrossRef]

S. J. Oldenburg, R. D. Averitt, S. L. Westcott, and N. J. Halas, “Nanoengineering of optical resonances,” Chem. Phys. Lett.288, 243–247 (1998).
[CrossRef]

R. D. Averitt, D. Sarkar, and N. J. Halas, “Plasmon resonance shifts of Au-coated Au2S nanoshells: insight into multicomponent nanoparticle growth,” Phys. Rev. Lett.78, 4217–4220 (1997).
[CrossRef]

Hazle, J. D.

L. R. Hirsch, R. J. Stafford, J. A. Bankson, S. R. Sershen, B. Rivera, R. E. Price, J. D. Hazle, N. J. Halas, and J. L. West, “Nanoshell-mediated near-infrared thermal therapy of tumors under magnetic resonance guidance,” Proc. Natl. Acad. Sci. USA100, 13549–13554 (2003).
[CrossRef]

Hirsch, L. R.

L. R. Hirsch, R. J. Stafford, J. A. Bankson, S. R. Sershen, B. Rivera, R. E. Price, J. D. Hazle, N. J. Halas, and J. L. West, “Nanoshell-mediated near-infrared thermal therapy of tumors under magnetic resonance guidance,” Proc. Natl. Acad. Sci. USA100, 13549–13554 (2003).
[CrossRef]

Holden, A. J.

J. B. Pendry, A. J. Holden, D. J. Robbins, and W. J. Stewart, “Magnetism from conductors and enhanced nonlinear phenomena,” IEEE Trans. Microwave Theory Tech.47, 2075–2084 (1999).
[CrossRef]

Hsieh, C.

Y. Pu, R. Grange, C. Hsieh, and D. Psaltis, “Nonlinear optical properties of core-shell nanocavities for enhanced second-harmonic generation,” Phys. Rev. Lett.104, 207402 (2010).
[CrossRef]

Jang, S. G.

S. Yang, S. G. Jang, D. Choi, S. Kim, and H. K. Yu, “Nanomachining by colloidal lithography,” Small2, 458–475 (2006).
[CrossRef]

Johnson, P. B.

P. B. Johnson and R. W. Christy, “Optical constants of the noble metals,” Phys. Rev. B6, 4370–4379 (1972).
[CrossRef]

Käll, M.

T. Pakizeh and M. Käll, “Unidirectional ultracompact optical nanoantennas,” Nano Lett.9, 2343–2349 (2009).
[CrossRef]

Kandulski, W.

M. C. Gwinner, E. Koroknay, L. Fu, P. Patoka, W. Kandulski, M. Giersig, and H. Giessen, “Periodic large-area metallic split-ring resonator metamaterial fabrication based on shadow nanosphere lithography,” Small5, 400–406 (2009).
[CrossRef]

A. Kosiorek, W. Kandulski, H. Glaczynska, and M. Giersig, “Fabrication of nanoscale rings, dots, and rods by combining shadow nanosphere lithography and annealed polystyrene nanosphere masks,” Small1, 439–444 (2005).
[CrossRef]

Karim, S.

F. Neubrech, A. Pucci, T. W. Cornelius, S. Karim, A. Garcia-Etxarri, and J. Aizpurua, “Resonant plasmonic and vibrational coupling in a tailored nanoantenna for infrared detection,” Phys. Rev. Lett.101, 157403 (2008).
[CrossRef]

Kern, K.

D. Dregely, R. Taubert, J. Dorfmüller, R. Vogelgesang, K. Kern, and H. Giessen, “3D optical Yagi-Uda nanoantenna array,” Nat. Commun.2, 267 (2011).
[CrossRef]

Khanikaev, A. B.

C. Wu, A. B. Khanikaev, R. Adato, N. Arju, A. Ali Yanik, H. Altug, and G. Shvets, “Fano-resonant asymmetric metamaterials for ultrasensitive spectroscopy and identification of molecular monolayers,” Nat. Mater.11, 69–75 (2012).
[CrossRef]

Kim, S.

S. Yang, S. G. Jang, D. Choi, S. Kim, and H. K. Yu, “Nanomachining by colloidal lithography,” Small2, 458–475 (2006).
[CrossRef]

King, N. S.

N. S. King, Y. Li, C. Ayala-Orozco, T. Brannan, P. Nordlander, and N. J. Halas, “Angle- and spectral-dependent light scattering from plasmonic nanocups,” ACS Nano5, 7254–7262 (2011).
[CrossRef]

Klein, M. W.

S. Linden, C. Enkrich, G. Dolling, M. W. Klein, J. Zhou, T. Koschny, C. M. Soukoulis, S. Burger, F. Schmidt, and M. Wegener, “Photonic metamaterials: magnetism at optical frequencies,” IEEE J. Sel. Top. Quantum Electron.12, 1097–1105 (2006).
[CrossRef]

Koroknay, E.

M. C. Gwinner, E. Koroknay, L. Fu, P. Patoka, W. Kandulski, M. Giersig, and H. Giessen, “Periodic large-area metallic split-ring resonator metamaterial fabrication based on shadow nanosphere lithography,” Small5, 400–406 (2009).
[CrossRef]

Koschny, T.

S. Linden, C. Enkrich, G. Dolling, M. W. Klein, J. Zhou, T. Koschny, C. M. Soukoulis, S. Burger, F. Schmidt, and M. Wegener, “Photonic metamaterials: magnetism at optical frequencies,” IEEE J. Sel. Top. Quantum Electron.12, 1097–1105 (2006).
[CrossRef]

Kosiorek, A.

A. Kosiorek, W. Kandulski, H. Glaczynska, and M. Giersig, “Fabrication of nanoscale rings, dots, and rods by combining shadow nanosphere lithography and annealed polystyrene nanosphere masks,” Small1, 439–444 (2005).
[CrossRef]

Kuhl, J.

Lagae, L.

J. Ye, N. Verellen, W. Van Roy, L. Lagae, G. Maes, G. Borghs, and P. Van Dorpe, “Plasmonic modes of metallic semishells in a polymer film,” ACS Nano4, 1457–1464 (2010).
[CrossRef]

J. Ye, L. Lagae, G. Maes, G. Borghs, and P. Van Dorpe, “Symmetry breaking induced optical properties of gold open shell nanostructures,” Opt. Express17, 23765–23771 (2009).
[CrossRef]

Lal, S.

N. J. Halas, S. Lal, W. Chang, S. Link, and P. Nordlander, “Plasmons in strongly coupled metallic nanostructures,” Chem. Rev.111, 3913–3961 (2011).
[CrossRef]

Lassiter, J. B.

S. Mukherjee, H. Sobhani, J. B. Lassiter, R. Bardhan, P. Nordlander, and N. J. Halas, “Fanoshells: nanoparticles with built-in Fano resonances,” Nano Lett.10, 2694–2701 (2010).
[CrossRef]

Lederer, F.

Li, Y.

N. S. King, Y. Li, C. Ayala-Orozco, T. Brannan, P. Nordlander, and N. J. Halas, “Angle- and spectral-dependent light scattering from plasmonic nanocups,” ACS Nano5, 7254–7262 (2011).
[CrossRef]

Linden, S.

S. Linden, C. Enkrich, G. Dolling, M. W. Klein, J. Zhou, T. Koschny, C. M. Soukoulis, S. Burger, F. Schmidt, and M. Wegener, “Photonic metamaterials: magnetism at optical frequencies,” IEEE J. Sel. Top. Quantum Electron.12, 1097–1105 (2006).
[CrossRef]

Link, S.

N. J. Halas, S. Lal, W. Chang, S. Link, and P. Nordlander, “Plasmons in strongly coupled metallic nanostructures,” Chem. Rev.111, 3913–3961 (2011).
[CrossRef]

Liu, H.

N. Liu, H. Liu, S. Zhu, and H. Giessen, “Stereometamaterials,” Nat. Photonics3, 157–162 (2009).
[CrossRef]

Liu, N.

N. Liu and H. Giessen, “Coupling effects in optical metamaterials,” Angew. Chem. Int. Ed.49, 9838–9852 (2010).
[CrossRef]

N. Liu, H. Liu, S. Zhu, and H. Giessen, “Stereometamaterials,” Nat. Photonics3, 157–162 (2009).
[CrossRef]

H. Guo, N. Liu, L. Fu, T. P. Meyrath, T. Zentgraf, H. Schweizer, and H. Giessen, “Resonance hybridization in double split-ring resonator metamaterials,” Opt. Express15, 12095–12101 (2007).
[CrossRef]

Maes, G.

J. Ye, N. Verellen, W. Van Roy, L. Lagae, G. Maes, G. Borghs, and P. Van Dorpe, “Plasmonic modes of metallic semishells in a polymer film,” ACS Nano4, 1457–1464 (2010).
[CrossRef]

J. Ye, P. Van Dorpe, W. Van Roy, G. Borghs, and G. Maes, “Fabrication, characterization, and optical properties of gold nanobowl submonolayer structures,” Langmuir25, 1822–1827 (2009).
[CrossRef]

J. Ye, L. Lagae, G. Maes, G. Borghs, and P. Van Dorpe, “Symmetry breaking induced optical properties of gold open shell nanostructures,” Opt. Express17, 23765–23771 (2009).
[CrossRef]

Mahajan, S.

R. M. Cole, J. J. Baumberg, F. J. Garcia de Abajo, S. Mahajan, M. Abdelsalam, and P. N. Bartlett, “Understanding plasmons in nanoscale voids,” Nano Lett.7, 2094–2100 (2007).
[CrossRef]

Meyrath, T. P.

Mirin, N. A.

N. A. Mirin and N. J. Halas, “Light-bending nanoparticles,” Nano Lett.9, 1255–1259 (2009).
[CrossRef]

Mukherjee, S.

S. Mukherjee, H. Sobhani, J. B. Lassiter, R. Bardhan, P. Nordlander, and N. J. Halas, “Fanoshells: nanoparticles with built-in Fano resonances,” Nano Lett.10, 2694–2701 (2010).
[CrossRef]

Neubrech, F.

F. Neubrech, A. Pucci, T. W. Cornelius, S. Karim, A. Garcia-Etxarri, and J. Aizpurua, “Resonant plasmonic and vibrational coupling in a tailored nanoantenna for infrared detection,” Phys. Rev. Lett.101, 157403 (2008).
[CrossRef]

Nordlander, P.

N. J. Halas, S. Lal, W. Chang, S. Link, and P. Nordlander, “Plasmons in strongly coupled metallic nanostructures,” Chem. Rev.111, 3913–3961 (2011).
[CrossRef]

N. S. King, Y. Li, C. Ayala-Orozco, T. Brannan, P. Nordlander, and N. J. Halas, “Angle- and spectral-dependent light scattering from plasmonic nanocups,” ACS Nano5, 7254–7262 (2011).
[CrossRef]

S. Mukherjee, H. Sobhani, J. B. Lassiter, R. Bardhan, P. Nordlander, and N. J. Halas, “Fanoshells: nanoparticles with built-in Fano resonances,” Nano Lett.10, 2694–2701 (2010).
[CrossRef]

E. Prodan, C. Radloff, N. J. Halas, and P. Nordlander, “A hybridization model for the plasmon response of complex nanostructures,” Science302, 419–422 (2003).
[CrossRef]

Oldenburg, S. J.

S. J. Oldenburg, R. D. Averitt, S. L. Westcott, and N. J. Halas, “Nanoengineering of optical resonances,” Chem. Phys. Lett.288, 243–247 (1998).
[CrossRef]

Osten, W.

L. Fu, P. Schau, K. Frenner, H. Schweizer, J. Zhao, B. Frank, L. Wollet, P. Gaiser, B. Gompf, H. Giessen, and W. Osten, “Experimental demonstration of dispersion engineering through mode interactions in plasmonic microcavities,” Proc. SPIE8423, 84232I (2012).
[CrossRef]

Ph. Schau, K. Frenner, L. Fu, H. Schweizer, H. Giessen, and W. Osten, “Design of highly transmissive metallic meander stacks with different grating periodicities for subwavelength-imaging applications,” Opt. Express19, 3627–3636 (2011).
[CrossRef]

Pakizeh, T.

T. Pakizeh and M. Käll, “Unidirectional ultracompact optical nanoantennas,” Nano Lett.9, 2343–2349 (2009).
[CrossRef]

Patoka, P.

M. C. Gwinner, E. Koroknay, L. Fu, P. Patoka, W. Kandulski, M. Giersig, and H. Giessen, “Periodic large-area metallic split-ring resonator metamaterial fabrication based on shadow nanosphere lithography,” Small5, 400–406 (2009).
[CrossRef]

Pendry, J. B.

J. B. Pendry, A. J. Holden, D. J. Robbins, and W. J. Stewart, “Magnetism from conductors and enhanced nonlinear phenomena,” IEEE Trans. Microwave Theory Tech.47, 2075–2084 (1999).
[CrossRef]

Price, R. E.

L. R. Hirsch, R. J. Stafford, J. A. Bankson, S. R. Sershen, B. Rivera, R. E. Price, J. D. Hazle, N. J. Halas, and J. L. West, “Nanoshell-mediated near-infrared thermal therapy of tumors under magnetic resonance guidance,” Proc. Natl. Acad. Sci. USA100, 13549–13554 (2003).
[CrossRef]

Prodan, E.

E. Prodan, C. Radloff, N. J. Halas, and P. Nordlander, “A hybridization model for the plasmon response of complex nanostructures,” Science302, 419–422 (2003).
[CrossRef]

Psaltis, D.

Y. Pu, R. Grange, C. Hsieh, and D. Psaltis, “Nonlinear optical properties of core-shell nanocavities for enhanced second-harmonic generation,” Phys. Rev. Lett.104, 207402 (2010).
[CrossRef]

Pu, Y.

Y. Pu, R. Grange, C. Hsieh, and D. Psaltis, “Nonlinear optical properties of core-shell nanocavities for enhanced second-harmonic generation,” Phys. Rev. Lett.104, 207402 (2010).
[CrossRef]

Pucci, A.

F. Neubrech, A. Pucci, T. W. Cornelius, S. Karim, A. Garcia-Etxarri, and J. Aizpurua, “Resonant plasmonic and vibrational coupling in a tailored nanoantenna for infrared detection,” Phys. Rev. Lett.101, 157403 (2008).
[CrossRef]

Radloff, C.

E. Prodan, C. Radloff, N. J. Halas, and P. Nordlander, “A hybridization model for the plasmon response of complex nanostructures,” Science302, 419–422 (2003).
[CrossRef]

Rivera, B.

L. R. Hirsch, R. J. Stafford, J. A. Bankson, S. R. Sershen, B. Rivera, R. E. Price, J. D. Hazle, N. J. Halas, and J. L. West, “Nanoshell-mediated near-infrared thermal therapy of tumors under magnetic resonance guidance,” Proc. Natl. Acad. Sci. USA100, 13549–13554 (2003).
[CrossRef]

Robbins, D. J.

J. B. Pendry, A. J. Holden, D. J. Robbins, and W. J. Stewart, “Magnetism from conductors and enhanced nonlinear phenomena,” IEEE Trans. Microwave Theory Tech.47, 2075–2084 (1999).
[CrossRef]

Rockstuhl, C.

Sarkar, D.

R. D. Averitt, D. Sarkar, and N. J. Halas, “Plasmon resonance shifts of Au-coated Au2S nanoshells: insight into multicomponent nanoparticle growth,” Phys. Rev. Lett.78, 4217–4220 (1997).
[CrossRef]

Schau, P.

L. Fu, P. Schau, K. Frenner, H. Schweizer, J. Zhao, B. Frank, L. Wollet, P. Gaiser, B. Gompf, H. Giessen, and W. Osten, “Experimental demonstration of dispersion engineering through mode interactions in plasmonic microcavities,” Proc. SPIE8423, 84232I (2012).
[CrossRef]

Schau, Ph.

Schmidt, F.

S. Linden, C. Enkrich, G. Dolling, M. W. Klein, J. Zhou, T. Koschny, C. M. Soukoulis, S. Burger, F. Schmidt, and M. Wegener, “Photonic metamaterials: magnetism at optical frequencies,” IEEE J. Sel. Top. Quantum Electron.12, 1097–1105 (2006).
[CrossRef]

Schweizer, H.

Sershen, S. R.

L. R. Hirsch, R. J. Stafford, J. A. Bankson, S. R. Sershen, B. Rivera, R. E. Price, J. D. Hazle, N. J. Halas, and J. L. West, “Nanoshell-mediated near-infrared thermal therapy of tumors under magnetic resonance guidance,” Proc. Natl. Acad. Sci. USA100, 13549–13554 (2003).
[CrossRef]

Shvets, G.

C. Wu, A. B. Khanikaev, R. Adato, N. Arju, A. Ali Yanik, H. Altug, and G. Shvets, “Fano-resonant asymmetric metamaterials for ultrasensitive spectroscopy and identification of molecular monolayers,” Nat. Mater.11, 69–75 (2012).
[CrossRef]

Sobhani, H.

S. Mukherjee, H. Sobhani, J. B. Lassiter, R. Bardhan, P. Nordlander, and N. J. Halas, “Fanoshells: nanoparticles with built-in Fano resonances,” Nano Lett.10, 2694–2701 (2010).
[CrossRef]

Soukoulis, C. M.

S. Linden, C. Enkrich, G. Dolling, M. W. Klein, J. Zhou, T. Koschny, C. M. Soukoulis, S. Burger, F. Schmidt, and M. Wegener, “Photonic metamaterials: magnetism at optical frequencies,” IEEE J. Sel. Top. Quantum Electron.12, 1097–1105 (2006).
[CrossRef]

Stafford, R. J.

L. R. Hirsch, R. J. Stafford, J. A. Bankson, S. R. Sershen, B. Rivera, R. E. Price, J. D. Hazle, N. J. Halas, and J. L. West, “Nanoshell-mediated near-infrared thermal therapy of tumors under magnetic resonance guidance,” Proc. Natl. Acad. Sci. USA100, 13549–13554 (2003).
[CrossRef]

Stefani, F. D.

Stewart, W. J.

J. B. Pendry, A. J. Holden, D. J. Robbins, and W. J. Stewart, “Magnetism from conductors and enhanced nonlinear phenomena,” IEEE Trans. Microwave Theory Tech.47, 2075–2084 (1999).
[CrossRef]

Taminiau, T. H.

Taubert, R.

D. Dregely, R. Taubert, J. Dorfmüller, R. Vogelgesang, K. Kern, and H. Giessen, “3D optical Yagi-Uda nanoantenna array,” Nat. Commun.2, 267 (2011).
[CrossRef]

Van Dorpe, P.

P. Van Dorpe and J. Ye, “Semishells: versatile plasmonic nanoparticles,” ACS Nano5, 6774–6778 (2011).
[CrossRef]

J. Ye, N. Verellen, W. Van Roy, L. Lagae, G. Maes, G. Borghs, and P. Van Dorpe, “Plasmonic modes of metallic semishells in a polymer film,” ACS Nano4, 1457–1464 (2010).
[CrossRef]

J. Ye, P. Van Dorpe, W. Van Roy, G. Borghs, and G. Maes, “Fabrication, characterization, and optical properties of gold nanobowl submonolayer structures,” Langmuir25, 1822–1827 (2009).
[CrossRef]

J. Ye, L. Lagae, G. Maes, G. Borghs, and P. Van Dorpe, “Symmetry breaking induced optical properties of gold open shell nanostructures,” Opt. Express17, 23765–23771 (2009).
[CrossRef]

van Hulst, N. F.

Van Roy, W.

J. Ye, N. Verellen, W. Van Roy, L. Lagae, G. Maes, G. Borghs, and P. Van Dorpe, “Plasmonic modes of metallic semishells in a polymer film,” ACS Nano4, 1457–1464 (2010).
[CrossRef]

J. Ye, P. Van Dorpe, W. Van Roy, G. Borghs, and G. Maes, “Fabrication, characterization, and optical properties of gold nanobowl submonolayer structures,” Langmuir25, 1822–1827 (2009).
[CrossRef]

Verellen, N.

J. Ye, N. Verellen, W. Van Roy, L. Lagae, G. Maes, G. Borghs, and P. Van Dorpe, “Plasmonic modes of metallic semishells in a polymer film,” ACS Nano4, 1457–1464 (2010).
[CrossRef]

Vogelgesang, R.

D. Dregely, R. Taubert, J. Dorfmüller, R. Vogelgesang, K. Kern, and H. Giessen, “3D optical Yagi-Uda nanoantenna array,” Nat. Commun.2, 267 (2011).
[CrossRef]

Wegener, M.

S. Linden, C. Enkrich, G. Dolling, M. W. Klein, J. Zhou, T. Koschny, C. M. Soukoulis, S. Burger, F. Schmidt, and M. Wegener, “Photonic metamaterials: magnetism at optical frequencies,” IEEE J. Sel. Top. Quantum Electron.12, 1097–1105 (2006).
[CrossRef]

West, J. L.

L. R. Hirsch, R. J. Stafford, J. A. Bankson, S. R. Sershen, B. Rivera, R. E. Price, J. D. Hazle, N. J. Halas, and J. L. West, “Nanoshell-mediated near-infrared thermal therapy of tumors under magnetic resonance guidance,” Proc. Natl. Acad. Sci. USA100, 13549–13554 (2003).
[CrossRef]

Westcott, S. L.

S. J. Oldenburg, R. D. Averitt, S. L. Westcott, and N. J. Halas, “Nanoengineering of optical resonances,” Chem. Phys. Lett.288, 243–247 (1998).
[CrossRef]

Wollet, L.

L. Fu, P. Schau, K. Frenner, H. Schweizer, J. Zhao, B. Frank, L. Wollet, P. Gaiser, B. Gompf, H. Giessen, and W. Osten, “Experimental demonstration of dispersion engineering through mode interactions in plasmonic microcavities,” Proc. SPIE8423, 84232I (2012).
[CrossRef]

Wu, C.

C. Wu, A. B. Khanikaev, R. Adato, N. Arju, A. Ali Yanik, H. Altug, and G. Shvets, “Fano-resonant asymmetric metamaterials for ultrasensitive spectroscopy and identification of molecular monolayers,” Nat. Mater.11, 69–75 (2012).
[CrossRef]

Yang, S.

S. Yang, S. G. Jang, D. Choi, S. Kim, and H. K. Yu, “Nanomachining by colloidal lithography,” Small2, 458–475 (2006).
[CrossRef]

Ye, J.

P. Van Dorpe and J. Ye, “Semishells: versatile plasmonic nanoparticles,” ACS Nano5, 6774–6778 (2011).
[CrossRef]

J. Ye, N. Verellen, W. Van Roy, L. Lagae, G. Maes, G. Borghs, and P. Van Dorpe, “Plasmonic modes of metallic semishells in a polymer film,” ACS Nano4, 1457–1464 (2010).
[CrossRef]

J. Ye, P. Van Dorpe, W. Van Roy, G. Borghs, and G. Maes, “Fabrication, characterization, and optical properties of gold nanobowl submonolayer structures,” Langmuir25, 1822–1827 (2009).
[CrossRef]

J. Ye, L. Lagae, G. Maes, G. Borghs, and P. Van Dorpe, “Symmetry breaking induced optical properties of gold open shell nanostructures,” Opt. Express17, 23765–23771 (2009).
[CrossRef]

Yu, H. K.

S. Yang, S. G. Jang, D. Choi, S. Kim, and H. K. Yu, “Nanomachining by colloidal lithography,” Small2, 458–475 (2006).
[CrossRef]

Zentgraf, T.

Zhang, Y.

Y. Zhang, N. K. Grady, C. Ayala-Orozco, and N. J. Halas, “Three-dimensional nanostructures as highly efficient generators of second harmonic light,” Nano Lett.11, 5519–5523 (2011).
[CrossRef]

Zhao, J.

L. Fu, P. Schau, K. Frenner, H. Schweizer, J. Zhao, B. Frank, L. Wollet, P. Gaiser, B. Gompf, H. Giessen, and W. Osten, “Experimental demonstration of dispersion engineering through mode interactions in plasmonic microcavities,” Proc. SPIE8423, 84232I (2012).
[CrossRef]

J. Zhao, B. Frank, S. Burger, and H. Giessen, “Large-area high-quality plasmonic oligomers fabricated by angle-controlled colloidal nanolithography,” ACS Nano5, 9009–9016 (2011).
[CrossRef]

Zhou, J.

S. Linden, C. Enkrich, G. Dolling, M. W. Klein, J. Zhou, T. Koschny, C. M. Soukoulis, S. Burger, F. Schmidt, and M. Wegener, “Photonic metamaterials: magnetism at optical frequencies,” IEEE J. Sel. Top. Quantum Electron.12, 1097–1105 (2006).
[CrossRef]

Zhu, S.

N. Liu, H. Liu, S. Zhu, and H. Giessen, “Stereometamaterials,” Nat. Photonics3, 157–162 (2009).
[CrossRef]

ACS Nano

J. Ye, N. Verellen, W. Van Roy, L. Lagae, G. Maes, G. Borghs, and P. Van Dorpe, “Plasmonic modes of metallic semishells in a polymer film,” ACS Nano4, 1457–1464 (2010).
[CrossRef]

N. S. King, Y. Li, C. Ayala-Orozco, T. Brannan, P. Nordlander, and N. J. Halas, “Angle- and spectral-dependent light scattering from plasmonic nanocups,” ACS Nano5, 7254–7262 (2011).
[CrossRef]

P. Van Dorpe and J. Ye, “Semishells: versatile plasmonic nanoparticles,” ACS Nano5, 6774–6778 (2011).
[CrossRef]

J. Zhao, B. Frank, S. Burger, and H. Giessen, “Large-area high-quality plasmonic oligomers fabricated by angle-controlled colloidal nanolithography,” ACS Nano5, 9009–9016 (2011).
[CrossRef]

Angew. Chem. Int. Ed.

N. Liu and H. Giessen, “Coupling effects in optical metamaterials,” Angew. Chem. Int. Ed.49, 9838–9852 (2010).
[CrossRef]

Chem. Phys. Lett.

S. J. Oldenburg, R. D. Averitt, S. L. Westcott, and N. J. Halas, “Nanoengineering of optical resonances,” Chem. Phys. Lett.288, 243–247 (1998).
[CrossRef]

Chem. Rev.

N. J. Halas, S. Lal, W. Chang, S. Link, and P. Nordlander, “Plasmons in strongly coupled metallic nanostructures,” Chem. Rev.111, 3913–3961 (2011).
[CrossRef]

IEEE J. Sel. Top. Quantum Electron.

S. Linden, C. Enkrich, G. Dolling, M. W. Klein, J. Zhou, T. Koschny, C. M. Soukoulis, S. Burger, F. Schmidt, and M. Wegener, “Photonic metamaterials: magnetism at optical frequencies,” IEEE J. Sel. Top. Quantum Electron.12, 1097–1105 (2006).
[CrossRef]

IEEE Trans. Microwave Theory Tech.

J. B. Pendry, A. J. Holden, D. J. Robbins, and W. J. Stewart, “Magnetism from conductors and enhanced nonlinear phenomena,” IEEE Trans. Microwave Theory Tech.47, 2075–2084 (1999).
[CrossRef]

Langmuir

J. Ye, P. Van Dorpe, W. Van Roy, G. Borghs, and G. Maes, “Fabrication, characterization, and optical properties of gold nanobowl submonolayer structures,” Langmuir25, 1822–1827 (2009).
[CrossRef]

Nano Lett.

R. M. Cole, J. J. Baumberg, F. J. Garcia de Abajo, S. Mahajan, M. Abdelsalam, and P. N. Bartlett, “Understanding plasmons in nanoscale voids,” Nano Lett.7, 2094–2100 (2007).
[CrossRef]

S. Mukherjee, H. Sobhani, J. B. Lassiter, R. Bardhan, P. Nordlander, and N. J. Halas, “Fanoshells: nanoparticles with built-in Fano resonances,” Nano Lett.10, 2694–2701 (2010).
[CrossRef]

T. Pakizeh and M. Käll, “Unidirectional ultracompact optical nanoantennas,” Nano Lett.9, 2343–2349 (2009).
[CrossRef]

N. A. Mirin and N. J. Halas, “Light-bending nanoparticles,” Nano Lett.9, 1255–1259 (2009).
[CrossRef]

Y. Zhang, N. K. Grady, C. Ayala-Orozco, and N. J. Halas, “Three-dimensional nanostructures as highly efficient generators of second harmonic light,” Nano Lett.11, 5519–5523 (2011).
[CrossRef]

Nanotechnology

M. Cortie and M. Ford, “A plasmon-induced current loop in gold semi-shells,” Nanotechnology18, 235704 (2007).
[CrossRef]

Nat. Commun.

D. Dregely, R. Taubert, J. Dorfmüller, R. Vogelgesang, K. Kern, and H. Giessen, “3D optical Yagi-Uda nanoantenna array,” Nat. Commun.2, 267 (2011).
[CrossRef]

Nat. Mater.

C. Wu, A. B. Khanikaev, R. Adato, N. Arju, A. Ali Yanik, H. Altug, and G. Shvets, “Fano-resonant asymmetric metamaterials for ultrasensitive spectroscopy and identification of molecular monolayers,” Nat. Mater.11, 69–75 (2012).
[CrossRef]

Nat. Photonics

N. Liu, H. Liu, S. Zhu, and H. Giessen, “Stereometamaterials,” Nat. Photonics3, 157–162 (2009).
[CrossRef]

Opt. Express

Phys. Rev. B

P. B. Johnson and R. W. Christy, “Optical constants of the noble metals,” Phys. Rev. B6, 4370–4379 (1972).
[CrossRef]

Phys. Rev. Lett.

R. D. Averitt, D. Sarkar, and N. J. Halas, “Plasmon resonance shifts of Au-coated Au2S nanoshells: insight into multicomponent nanoparticle growth,” Phys. Rev. Lett.78, 4217–4220 (1997).
[CrossRef]

Y. Pu, R. Grange, C. Hsieh, and D. Psaltis, “Nonlinear optical properties of core-shell nanocavities for enhanced second-harmonic generation,” Phys. Rev. Lett.104, 207402 (2010).
[CrossRef]

F. Neubrech, A. Pucci, T. W. Cornelius, S. Karim, A. Garcia-Etxarri, and J. Aizpurua, “Resonant plasmonic and vibrational coupling in a tailored nanoantenna for infrared detection,” Phys. Rev. Lett.101, 157403 (2008).
[CrossRef]

Proc. Natl. Acad. Sci. USA

L. R. Hirsch, R. J. Stafford, J. A. Bankson, S. R. Sershen, B. Rivera, R. E. Price, J. D. Hazle, N. J. Halas, and J. L. West, “Nanoshell-mediated near-infrared thermal therapy of tumors under magnetic resonance guidance,” Proc. Natl. Acad. Sci. USA100, 13549–13554 (2003).
[CrossRef]

Proc. SPIE

L. Fu, P. Schau, K. Frenner, H. Schweizer, J. Zhao, B. Frank, L. Wollet, P. Gaiser, B. Gompf, H. Giessen, and W. Osten, “Experimental demonstration of dispersion engineering through mode interactions in plasmonic microcavities,” Proc. SPIE8423, 84232I (2012).
[CrossRef]

Science

E. Prodan, C. Radloff, N. J. Halas, and P. Nordlander, “A hybridization model for the plasmon response of complex nanostructures,” Science302, 419–422 (2003).
[CrossRef]

Small

A. Kosiorek, W. Kandulski, H. Glaczynska, and M. Giersig, “Fabrication of nanoscale rings, dots, and rods by combining shadow nanosphere lithography and annealed polystyrene nanosphere masks,” Small1, 439–444 (2005).
[CrossRef]

S. Yang, S. G. Jang, D. Choi, S. Kim, and H. K. Yu, “Nanomachining by colloidal lithography,” Small2, 458–475 (2006).
[CrossRef]

M. C. Gwinner, E. Koroknay, L. Fu, P. Patoka, W. Kandulski, M. Giersig, and H. Giessen, “Periodic large-area metallic split-ring resonator metamaterial fabrication based on shadow nanosphere lithography,” Small5, 400–406 (2009).
[CrossRef]

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Figures (4)

Fig. 1
Fig. 1

(a) Schematic drawing of stacked nanocups (b) Geometrical parameters and thickness of the inner Au layer g1, MgF2 spacer layer d and outer Au layer g2 (c) hexagonally close-packed polystyrene sphere monolayer (d) FIB cut of the experimental realization of the coupled nanocups with parameters [g1, d, g2] = [27, 56, 29] nm (e) FIB cut of the inner cup based on an evaporated gold layer g1 = 27nm (f) FIB cut of the outer cup with additional magnesium fluoride layer and g2 = 25nm Au layer (deviation from (d) due to fabricational tolerances)

Fig. 2
Fig. 2

Mode splitting in stacked nanocups: Comparison of reflectance spectra of the fabricated structures (Fig. 1) to simulated data. In analogy to the mode hybridization theory one additional reflectance dip appears for the stacked nanocup arrangement in simulation and experiment

Fig. 3
Fig. 3

Mode classification for stacked nanocups. (a) Visualization of analogy to split-ring-resonator modes and identification of symmetric and antisymmetric mode. (b) Electric mode via charge distribution from CST Microwave Studio. (c) Magnetic mode via y-component of the magnetic field in order to visualize magnetic moment coupling from CST Microwave Studio.

Fig. 4
Fig. 4

Variation of spacer thickness in stacked cups illustrated by three samples with parameters [g1, d1, g2] = [27, 56, 29] nm, [g1, d2, g2] = [27, 46, 29] nm, [g1, d3, g2] = [27, 36, 29] nm.

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