## Plasphonics : local hybridization of plasmons and phonons |

Optics Express, Vol. 21, Issue 4, pp. 4551-4559 (2013)

http://dx.doi.org/10.1364/OE.21.004551

Acrobat PDF (757 KB)

### Abstract

We show that the interaction between localized surface plasmons sustained by a metallic nano-antenna and delocalized phonons lying at the surface of an heteropolar semiconductor can generate a new class of hybrid electromagnetic modes. These *plasphonic modes* are investigated using an analytical model completed by accurate Green dyadic numerical simulations. When surface plasmon and surface phonon frequencies match, the optical resonances exhibit a large Rabi splitting typical of strongly interacting two-level systems. Based on numerical simulations of the electric near-field maps, we investigate the nature of the plaphonic excitations. In particular, we point out a strong local field enhancement boosted by the phononic surface. This effect is interpreted in terms of light harvesting by the plasmonic antenna from the phononic surface. We thus introduce the concept of *active phononic surfaces* that may be exploited for far-infared optoelectronic devices and sensors.

© 2013 OSA

## 1. Introduction

2. L. Novotny and B. Hecht, *Principles of Nano-Optics* (Cambridge U. PressNew York, 2006). [CrossRef]

4. S. Lal, S. Link, and N. J. Halas, “Nano-optics from sensing to waveguiding,” Nat. Photonics **1**, 641–648 (2007). [CrossRef]

5. R. Hillenbrand, T. Taubner, and F. Keilmann, “Phonon-enhanced light-matter interaction at the nanometre scale,” Nature **418**, 159–162 (2002). [CrossRef] [PubMed]

7. 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] [PubMed]

8. H. Wang, D. W. Brandl, F. Le, P. Nordlander, and N. J. Halas, “Nanorice: a hybrid plasmonic nanostructure,” Nano Lett. **6**, 827–832 (2006). [CrossRef] [PubMed]

12. A. Manjavacas, F. G. de Abajo, and P. Nordlander, “Quantum plexcitonics: strongly interacting plasmons and excitons,” Nano Lett. **11**, 2318–2323 (2011). [CrossRef] [PubMed]

*i.e.*between the transverse and the longitudinal optical phonon frequencies. In this frequency gap, the atomic vibrations generate electromagnetic fields that propagate along the surface with a strong localization in the perpendicular direction. These modes have been extensively studied by high resolution electron energy loss spectroscopy [13

13. S. Grabowski, T. Kampen, H. Nienhaus, and W. Monch, “Vibrational properties of GaN(0001) surfaces,” Appl. Surf. Sci. **123**, 33–37 (1998). [CrossRef]

15. A. Mooradian and G. B. Wright, “Observation of the interaction of plasmons with longitudinal optical phonons in GaAs,” Phys. Rev. Lett. **16**, 999–1001 (1966). [CrossRef]

*et al*[7

7. 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] [PubMed]

5. R. Hillenbrand, T. Taubner, and F. Keilmann, “Phonon-enhanced light-matter interaction at the nanometre scale,” Nature **418**, 159–162 (2002). [CrossRef] [PubMed]

6. M. S. Anderson, “Surface enhanced infrared absorption by coupling phonon and plasmon resonance,” Appl. Phys. Lett. **87**, 144102 (2005). [CrossRef]

*et al*[17

17. A. Huber, N. Ocelic, T. Taubner, and R. Hillenbrand, “Nanoscale resolved infrared probing of crystal structure and of plasmon-phonon coupling,” Nano Lett. **6**, 774–778 (2006). [CrossRef] [PubMed]

18. H. C. Kim and X. Cheng, “Infrared dipole antenna enhanced by surface phonon polaritons,” Opt. Lett. **35**, 3748–3750 (2010). [CrossRef] [PubMed]

## 2. Analytical approach

19. G. Yu, N. L. Rowell, and D. J. Lockwood, “Anisotropic infrared optical properties of GaN and sapphire,” J. Vac. Sci. Technol. A **22**, 1110–1114 (2004). [CrossRef]

20. D. Lockwood, G. Yu, and N. L. Rowell, “Optical phonon frequencies and damping in AlAs, GaP, GaAs, InP, InAs and InSb studied by oblique incidence infrared spectroscopy,” Solid State Commun. **136**, 404–409 (2005). [CrossRef]

_{1}(LO) and transverse E

_{1}(TO) phonons. Let

*ω*,

_{L}*ω*and

_{T}*γ*,

_{L}*γ*be respectively the E

_{T}_{1}(LO) and E

_{1}(TO) optical phonon frequencies and their corresponding damping parameters, the dielectric function reads [19

19. G. Yu, N. L. Rowell, and D. J. Lockwood, “Anisotropic infrared optical properties of GaN and sapphire,” J. Vac. Sci. Technol. A **22**, 1110–1114 (2004). [CrossRef]

20. D. Lockwood, G. Yu, and N. L. Rowell, “Optical phonon frequencies and damping in AlAs, GaP, GaAs, InP, InAs and InSb studied by oblique incidence infrared spectroscopy,” Solid State Commun. **136**, 404–409 (2005). [CrossRef]

*ε*

_{∞}are taken from reference [19

19. G. Yu, N. L. Rowell, and D. J. Lockwood, “Anisotropic infrared optical properties of GaN and sapphire,” J. Vac. Sci. Technol. A **22**, 1110–1114 (2004). [CrossRef]

*ε*(

*ω*) = −1 in the long-wavelength limit. Since the LO and TO phonon dampings are much smaller than the LO and TO frequencies [19

**22**, 1110–1114 (2004). [CrossRef]

20. D. Lockwood, G. Yu, and N. L. Rowell, “Optical phonon frequencies and damping in AlAs, GaP, GaAs, InP, InAs and InSb studied by oblique incidence infrared spectroscopy,” Solid State Commun. **136**, 404–409 (2005). [CrossRef]

*γ*and

_{L}*γ*terms in Eq. (1) can be neglected and using

_{T}*ε*(

*ω*) = −1, one obtains the surface phonon frequency

7. 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] [PubMed]

21. L. Novotny, “Effective wavelength scaling for optical antennas,” Phys. Rev. Lett. **98**, 266802 (2007). [CrossRef] [PubMed]

23. B. S. Guiton, V. Iberi, S. Li, D. N. Leonard, C. M. Parish, P. G. Kotula, M. Varela, G. C. Schatz, S. J. Pennycook, and J. P. Camden, “Correlated optical measurements and plasmon mapping of silver nanorods,” Nano Lett. **11**, 3482–3488 (2011). [CrossRef] [PubMed]

*ω*only depend on the antenna length L [21

_{p}21. L. Novotny, “Effective wavelength scaling for optical antennas,” Phys. Rev. Lett. **98**, 266802 (2007). [CrossRef] [PubMed]

*ω*=

_{p}*cπp/nL*, where

*p*is an integer that labels the surface plasmon mode order,

*n*is the effective optical index of the environment surrounding the antenna [21

21. L. Novotny, “Effective wavelength scaling for optical antennas,” Phys. Rev. Lett. **98**, 266802 (2007). [CrossRef] [PubMed]

22. H. Wei, A. Reyes-Coronado, P. Nordlander, J. Aizpurua, and H. Xu, “Multipolar plasmon resonances in individual Ag nanorice,” ACS Nano **4**, 2649–2654 (2010). [CrossRef] [PubMed]

*c*is the speed of light. The fundamental mode

*p*= 1 corresponds to a dipolar distribution of the electric field with surface polarization charges located at both antenna ends [23

23. B. S. Guiton, V. Iberi, S. Li, D. N. Leonard, C. M. Parish, P. G. Kotula, M. Varela, G. C. Schatz, S. J. Pennycook, and J. P. Camden, “Correlated optical measurements and plasmon mapping of silver nanorods,” Nano Lett. **11**, 3482–3488 (2011). [CrossRef] [PubMed]

**R**= (0, 0,

*R*=

*Z*+

*h*/2) (Z being the width of the air-gap and h the height of the antenna (Fig. 1)). Its polarizability is described by a lorentzian function where

*ω*

_{1}=

*cπ*/

*nL*is the resonance frequency,

*γ*

_{1}is a damping parameter and

*α*

_{0}is a static polarizability fixed to its maximum value, i.e. to the antenna volume (in CGS units). In the framework of the field susceptibility formalism [24

24. C. Girard, “Near field in nanostructures,” Rep. Prog. Phys. **68**1883–1933 (2005) [CrossRef]

25. O. Keller, M. Xiao, and S. Bozhevolnyi, “Configurational resonances in optical near-field microscopy: a rigorous point-dipole approach,” Surf. Sci. **280**, 217–230 (1993). [CrossRef]

**S**represents the field-susceptibility of the surface,

**I**is the identity tensor, and

**E**

_{0}(

**R**,

*ω*) is the incident electric field. The wavelengths of the surface plasmons considered here are of the order of 20

*μ*m, i.e. much larger than the spacing Z (few tens of nanometers) between the dipole antenna and the semiconductor surface. In that case, the dipole-surface interaction is described by the near-field contribution to

**S**[25

25. O. Keller, M. Xiao, and S. Bozhevolnyi, “Configurational resonances in optical near-field microscopy: a rigorous point-dipole approach,” Surf. Sci. **280**, 217–230 (1993). [CrossRef]

*R*

^{3}term. For negligible surface plasmon and surface phonon dampings, resonances occur for frequencies satisfying where ℜ denotes the real part. Replacing Eqs. (1)–(2) into Eq. (6) leads to the bi–squared equation where

*δ*= 0 in Eq. (7) gives

*two independent solutions ω*and

_{sph}*ω*(

_{SP}*Z*). Conversely, for

*δ*≠ 0, the coupling between the surface phonons and the dipole-antenna resonance can occur. The two real solutions

*ω*

_{+}and

*ω*

_{−}of Eq. (7) are plotted in Fig. 2(a) as a function of the dipole antenna resonance frequency

*ω*

_{1}and for different dipole–to–surface separations. By changing

*ω*

_{1}, the surface plasmon frequency

*ω*(

_{SP}*Z*) can be tuned to the surface phonon frequency

*ω*and an anti–crossing typical of Rabi–splitted two–level systems is observed [26

_{sph}26. J. Dintinger, S. Klein, F. Bustos, W. L. Barnes, and T. W. Ebbesen, “Strong coupling between surface plasmon-polaritons and organic molecules in subwavelength hole arrays,” Phys. Rev. B **71**, 035424 (2005). [CrossRef]

27. L. Novotny, “Strong coupling, energy splitting, and level crossings: a classical perspective,” Am. J. Phys. **78**, 1199–1202 (2010). [CrossRef]

*ω*(

_{SP}*Z*) =

*ω*and

_{sph}*δ*<<

*ω*in Eq. (7), one obtains the Rabi splitting Δ The Rabi splitting is clearly due to the interaction between the dipole antenna and the surface phonons and is proportional to the LO-TO splitting

_{sph}*δ*, i.e. to the square root of the electromagnetic field generated by the surface phonons. It is also a near-field effect since the Rabi splitting rapidly closes up as (

*Z*+

*h*/2)

^{−3/2}with increasing separation Z (Fig. 2(b)).

## 3. Full numerical simulations

28. O. J. F. Martin, C. Girard, and A. Dereux, “Generalized field propagator for electromagnetic scattering and light confinement,” Phys. Rev. Lett. **74**, 526 (1995). [CrossRef] [PubMed]

29. D. Barchiesi, C. Girard, O. J. F. Martin, D. Van Labeke, and D. Courjon, “Computing the optical near-field distributions around complex subwavelength surface structures: a comparative study of different methods,” Phys. Rev. E **54**4285–4292 (1996). [CrossRef]

30. M. A. Ordal, L. L. Long, R. J. Bell, S. E. Bell, R. W. Bell, J. Alexander, and C. A. Ward, “Optical properties of the metals Al, Co, Cu, Au, Fe, Pb, Ni, Pd, Pt, Ag, Ti, and W in the infrared and far infrared,” Appl. Opt. **22**, 1099–1119 (1983). [CrossRef] [PubMed]

31. S. Aksu, A. A. Yanik, R. Adato, A. Artar, M. Huang, and H. Altug, “High-throughput nanofabrication of infrared plasmonic nanoantenna arrays for vibrational nanospectroscopy,” Nano Lett. **10**, 2511–2518 (2010). [CrossRef] [PubMed]

*μ*m. The two branches in Fig. 2(a) are associated with hybrid surface plasmon-surface phonon excitations hereafter named plasphonic excitations. The extinction spectrum in Fig. 2(c) shows the corresponding Rabi-splitted peaks. The linewidth of these peaks are much smaller than the Rabi splitting, thereby confirming the strong coupling regime. The analytical model overestimates the Rabi splitting because the actual polarizability of gold is smaller than the antenna volume and also because of the finite width of the antenna. Plasmon and phonon dampings also reduce the Rabi splitting. One can notice that a dipole located at Z=30 nm gives nearly the same Rabi splitting as the antenna in-contact with the heteropolar surface.

*Z*

^{−3/2}in agreement with the analytical model. Moreover, the analytical Rabi splitting (Eq. (8)) has been adjusted to the numerical simulations using the polarisability

*α*

_{0}as a fitting parameter. To do so, the Z-values of the analytical model were shifted by 30 nm, which corresponds to the equivalent dipole location. The so-obtained polarizability

*α*

_{0}is 30 % smaller than the antenna volume assumed initially.

*ω*

_{+}= 800 and 740 cm

^{−1}of the upper plasphonic branches, exhibit spatial distributions which are typical of dipolar surface plasmons (Figs. 3(a)–3(b)). For the antenna in-contact with the GaN surface (Fig. 3(a)) the Rabi splitting is maximum and the electric near-field enhancement reaches a factor 17 at the antenna ends. With a 20 nm air-gap (Fig. 3(b)), the electric-field enhancement is reduced because of the weaker surface plasmon-surface phonon interaction.

*δ*=0) there are no (electromagnetic) surface phonons. Nevertheless, the surface is still responsible for a dipole image effect which impacts the surface plasmon frequency

*ω*(

_{SP}*Z*) and the electric field distribution of the gold antenna. To simulate this situation we have removed the polar phonon contribution to the dielectric response which then reduces to

*ε*(

*ω*) =

*ε*

_{∞}(

*ω*=

_{L}*ω*in Eq. (1)). The corresponding near-field distribution is shown in Fig. 3(c). As can be seen, the field enhancement is very weak compared to the strong interaction regime (Fig. 3(a)). This clearly points out the interest of the plasphonic excitations : the strong coupling between polar surface phonons and surface plasmons allows for enhancing the electric near-field amplitude of the gold nano-antenna by nearly one order of magnitude (Figs. 3(a)–3(c)).

_{T}*ω*

_{−}= 540 cm

^{−1}of the lower plasphonic branch. The near-field distribution is different from the typical dipolar distribution (Fig. 3(a)) and resembles that of a high order Fabry-Perot mode [23

23. B. S. Guiton, V. Iberi, S. Li, D. N. Leonard, C. M. Parish, P. G. Kotula, M. Varela, G. C. Schatz, S. J. Pennycook, and J. P. Camden, “Correlated optical measurements and plasmon mapping of silver nanorods,” Nano Lett. **11**, 3482–3488 (2011). [CrossRef] [PubMed]

*L*. The wavelengths of such confined modes, labeled by an integer

*l*, are given by where only modes with electric field distributions that are anti-symmetric with respect to the antenna center are considered. This symmetry restriction is imposed by the dipolar surface plasmon of the antenna (Fig. 3(a)) which is anti-symmetric. From Fig. 3(d), one can notice that the antenna is acting as a 7

*λ*/(2

*n*) cavity (i.e.

_{eff}*l*= 3). Hence, using a cavity length L = 4.5

*μ*m and

*λ*= 1/

*ω*

_{−}= 18.5

*μ*m, one obtains an effective optical index

*n*= 14.4. This value is larger than the optical index of GaN (around 7.5 at

_{eff}*ω*

_{−}= 540 cm

^{−1}) due to the contribution of the gold antenna. Indeed, in the frame of this simple confinement based assumption, the effective optical index accounts for the interaction between the plasmonic and the phononic excitations.

## 4. Conclusion

*active phononic surface*: the electromagnetic field carried by the surface phonons of an heteropolar semiconductor can be harvested by the metallic antenna via the strong near-field interaction thus leading to additional field enhancement. Plasmonic laser antenna [32

32. E. Cubukcu, E. A. Kort, K. B. Crozier, and F. Capasso, “Plasmonic laser antenna,” Appl. Phys. Lett. **89**, 093120 (2006). [CrossRef]

## Acknowledgments

## References and links

1. | C. F. Bohren and D. R. Huffman, |

2. | L. Novotny and B. Hecht, |

3. | H. A. Atwater and A. Polman, “Plasmonics for improved photovoltaic devices,” Nat. Mater. |

4. | S. Lal, S. Link, and N. J. Halas, “Nano-optics from sensing to waveguiding,” Nat. Photonics |

5. | R. Hillenbrand, T. Taubner, and F. Keilmann, “Phonon-enhanced light-matter interaction at the nanometre scale,” Nature |

6. | M. S. Anderson, “Surface enhanced infrared absorption by coupling phonon and plasmon resonance,” Appl. Phys. Lett. |

7. | 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. |

8. | H. Wang, D. W. Brandl, F. Le, P. Nordlander, and N. J. Halas, “Nanorice: a hybrid plasmonic nanostructure,” Nano Lett. |

9. | G. A. Wurtz, P. R. Evans, W. Hendren, R. Atkinson, W. Dickson, R. J. Pollard, A. V. Zayats, W. Harrison, and C. Bower, “Molecular plasmonics with tunable exciton-plasmon coupling strength in J-aggregate hybridized Au nanorod assemblies,” Nano Lett. |

10. | N. T. Fofang, T. H. Park, O. Neumann, N. A. Mirin, P. Nordlander, and N. J. Halas, “Plexcitonic nanoparticles: plasmon-exciton coupling in nanoshell-J-aggregate complexes,” Nano Lett. |

11. | S. Savasta, R. Saija, A. Ridolfo, O. Di Stefano, P. Denti, and F. Borghese, “Nanopolaritons: vacuum rabi splitting with a single quantum dot in the center of a dimer nanoantenna,” ACS Nano |

12. | A. Manjavacas, F. G. de Abajo, and P. Nordlander, “Quantum plexcitonics: strongly interacting plasmons and excitons,” Nano Lett. |

13. | S. Grabowski, T. Kampen, H. Nienhaus, and W. Monch, “Vibrational properties of GaN(0001) surfaces,” Appl. Surf. Sci. |

14. | N. Esser and W. Richter, |

15. | A. Mooradian and G. B. Wright, “Observation of the interaction of plasmons with longitudinal optical phonons in GaAs,” Phys. Rev. Lett. |

16. | M. Abstreiter, G. Cardona, and A. Pinczuk, |

17. | A. Huber, N. Ocelic, T. Taubner, and R. Hillenbrand, “Nanoscale resolved infrared probing of crystal structure and of plasmon-phonon coupling,” Nano Lett. |

18. | H. C. Kim and X. Cheng, “Infrared dipole antenna enhanced by surface phonon polaritons,” Opt. Lett. |

19. | G. Yu, N. L. Rowell, and D. J. Lockwood, “Anisotropic infrared optical properties of GaN and sapphire,” J. Vac. Sci. Technol. A |

20. | D. Lockwood, G. Yu, and N. L. Rowell, “Optical phonon frequencies and damping in AlAs, GaP, GaAs, InP, InAs and InSb studied by oblique incidence infrared spectroscopy,” Solid State Commun. |

21. | L. Novotny, “Effective wavelength scaling for optical antennas,” Phys. Rev. Lett. |

22. | H. Wei, A. Reyes-Coronado, P. Nordlander, J. Aizpurua, and H. Xu, “Multipolar plasmon resonances in individual Ag nanorice,” ACS Nano |

23. | B. S. Guiton, V. Iberi, S. Li, D. N. Leonard, C. M. Parish, P. G. Kotula, M. Varela, G. C. Schatz, S. J. Pennycook, and J. P. Camden, “Correlated optical measurements and plasmon mapping of silver nanorods,” Nano Lett. |

24. | C. Girard, “Near field in nanostructures,” Rep. Prog. Phys. |

25. | O. Keller, M. Xiao, and S. Bozhevolnyi, “Configurational resonances in optical near-field microscopy: a rigorous point-dipole approach,” Surf. Sci. |

26. | J. Dintinger, S. Klein, F. Bustos, W. L. Barnes, and T. W. Ebbesen, “Strong coupling between surface plasmon-polaritons and organic molecules in subwavelength hole arrays,” Phys. Rev. B |

27. | L. Novotny, “Strong coupling, energy splitting, and level crossings: a classical perspective,” Am. J. Phys. |

28. | O. J. F. Martin, C. Girard, and A. Dereux, “Generalized field propagator for electromagnetic scattering and light confinement,” Phys. Rev. Lett. |

29. | D. Barchiesi, C. Girard, O. J. F. Martin, D. Van Labeke, and D. Courjon, “Computing the optical near-field distributions around complex subwavelength surface structures: a comparative study of different methods,” Phys. Rev. E |

30. | M. A. Ordal, L. L. Long, R. J. Bell, S. E. Bell, R. W. Bell, J. Alexander, and C. A. Ward, “Optical properties of the metals Al, Co, Cu, Au, Fe, Pb, Ni, Pd, Pt, Ag, Ti, and W in the infrared and far infrared,” Appl. Opt. |

31. | S. Aksu, A. A. Yanik, R. Adato, A. Artar, M. Huang, and H. Altug, “High-throughput nanofabrication of infrared plasmonic nanoantenna arrays for vibrational nanospectroscopy,” Nano Lett. |

32. | E. Cubukcu, E. A. Kort, K. B. Crozier, and F. Capasso, “Plasmonic laser antenna,” Appl. Phys. Lett. |

**OCIS Codes**

(240.0240) Optics at surfaces : Optics at surfaces

(300.0300) Spectroscopy : Spectroscopy

**ToC Category:**

Optics at Surfaces

**History**

Original Manuscript: November 23, 2012

Revised Manuscript: January 17, 2013

Manuscript Accepted: January 18, 2013

Published: February 14, 2013

**Citation**

Renaud Marty, Adnen Mlayah, Arnaud Arbouet, Christian Girard, and Sudhiranjan Tripathy, "Plasphonics : local hybridization of plasmons and phonons," Opt. Express **21**, 4551-4559 (2013)

http://www.opticsinfobase.org/oe/abstract.cfm?URI=oe-21-4-4551

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### References

- C. F. Bohren and D. R. Huffman, Absorption and Scattering of Light by Small Particles (New YorkWiley-Interscience, 1983).
- L. Novotny and B. Hecht, Principles of Nano-Optics (Cambridge U. PressNew York, 2006). [CrossRef]
- H. A. Atwater and A. Polman, “Plasmonics for improved photovoltaic devices,” Nat. Mater.9, 205–213 (2010). [CrossRef] [PubMed]
- S. Lal, S. Link, and N. J. Halas, “Nano-optics from sensing to waveguiding,” Nat. Photonics1, 641–648 (2007). [CrossRef]
- R. Hillenbrand, T. Taubner, and F. Keilmann, “Phonon-enhanced light-matter interaction at the nanometre scale,” Nature418, 159–162 (2002). [CrossRef] [PubMed]
- M. S. Anderson, “Surface enhanced infrared absorption by coupling phonon and plasmon resonance,” Appl. Phys. Lett.87, 144102 (2005). [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] [PubMed]
- H. Wang, D. W. Brandl, F. Le, P. Nordlander, and N. J. Halas, “Nanorice: a hybrid plasmonic nanostructure,” Nano Lett.6, 827–832 (2006). [CrossRef] [PubMed]
- G. A. Wurtz, P. R. Evans, W. Hendren, R. Atkinson, W. Dickson, R. J. Pollard, A. V. Zayats, W. Harrison, and C. Bower, “Molecular plasmonics with tunable exciton-plasmon coupling strength in J-aggregate hybridized Au nanorod assemblies,” Nano Lett.7, 1297–1303 (2007). [CrossRef] [PubMed]
- N. T. Fofang, T. H. Park, O. Neumann, N. A. Mirin, P. Nordlander, and N. J. Halas, “Plexcitonic nanoparticles: plasmon-exciton coupling in nanoshell-J-aggregate complexes,” Nano Lett.8, 3481–3487 (2008). [CrossRef] [PubMed]
- S. Savasta, R. Saija, A. Ridolfo, O. Di Stefano, P. Denti, and F. Borghese, “Nanopolaritons: vacuum rabi splitting with a single quantum dot in the center of a dimer nanoantenna,” ACS Nano4, 6369–6376 (2010). [CrossRef] [PubMed]
- A. Manjavacas, F. G. de Abajo, and P. Nordlander, “Quantum plexcitonics: strongly interacting plasmons and excitons,” Nano Lett.11, 2318–2323 (2011). [CrossRef] [PubMed]
- S. Grabowski, T. Kampen, H. Nienhaus, and W. Monch, “Vibrational properties of GaN(0001) surfaces,” Appl. Surf. Sci.123, 33–37 (1998). [CrossRef]
- N. Esser and W. Richter, Raman Scattering from Surface Phonons (Springer Berlin / Heidelberg, 96–168, 2000).
- A. Mooradian and G. B. Wright, “Observation of the interaction of plasmons with longitudinal optical phonons in GaAs,” Phys. Rev. Lett.16, 999–1001 (1966). [CrossRef]
- M. Abstreiter, G. Cardona, and A. Pinczuk, Light Scattering by Free Carrier Excitations in Semiconductors (Springer-Verlag, Berlin, 1984).
- A. Huber, N. Ocelic, T. Taubner, and R. Hillenbrand, “Nanoscale resolved infrared probing of crystal structure and of plasmon-phonon coupling,” Nano Lett.6, 774–778 (2006). [CrossRef] [PubMed]
- H. C. Kim and X. Cheng, “Infrared dipole antenna enhanced by surface phonon polaritons,” Opt. Lett.35, 3748–3750 (2010). [CrossRef] [PubMed]
- G. Yu, N. L. Rowell, and D. J. Lockwood, “Anisotropic infrared optical properties of GaN and sapphire,” J. Vac. Sci. Technol. A22, 1110–1114 (2004). [CrossRef]
- D. Lockwood, G. Yu, and N. L. Rowell, “Optical phonon frequencies and damping in AlAs, GaP, GaAs, InP, InAs and InSb studied by oblique incidence infrared spectroscopy,” Solid State Commun.136, 404–409 (2005). [CrossRef]
- L. Novotny, “Effective wavelength scaling for optical antennas,” Phys. Rev. Lett.98, 266802 (2007). [CrossRef] [PubMed]
- H. Wei, A. Reyes-Coronado, P. Nordlander, J. Aizpurua, and H. Xu, “Multipolar plasmon resonances in individual Ag nanorice,” ACS Nano4, 2649–2654 (2010). [CrossRef] [PubMed]
- B. S. Guiton, V. Iberi, S. Li, D. N. Leonard, C. M. Parish, P. G. Kotula, M. Varela, G. C. Schatz, S. J. Pennycook, and J. P. Camden, “Correlated optical measurements and plasmon mapping of silver nanorods,” Nano Lett.11, 3482–3488 (2011). [CrossRef] [PubMed]
- C. Girard, “Near field in nanostructures,” Rep. Prog. Phys.681883–1933 (2005) [CrossRef]
- O. Keller, M. Xiao, and S. Bozhevolnyi, “Configurational resonances in optical near-field microscopy: a rigorous point-dipole approach,” Surf. Sci.280, 217–230 (1993). [CrossRef]
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