OSA's Digital Library

Virtual Journal for Biomedical Optics

Virtual Journal for Biomedical Optics

| EXPLORING THE INTERFACE OF LIGHT AND BIOMEDICINE

  • Editors: Andrew Dunn and Anthony Durkin
  • Vol. 8, Iss. 6 — Jun. 27, 2013
« Show journal navigation

Use of a gold reflecting-layer in optical antenna substrates for increase of photoluminescence enhancement

Roberto Fernandez-Garcia, Mohsen Rahmani, Minghui Hong, Stefan A. Maier, and Yannick Sonnefraud  »View Author Affiliations


Optics Express, Vol. 21, Issue 10, pp. 12552-12561 (2013)
http://dx.doi.org/10.1364/OE.21.012552


View Full Text Article

Acrobat PDF (2654 KB)





Browse Journals / Lookup Meetings

Browse by Journal and Year


   


Lookup Conference Papers

Close Browse Journals / Lookup Meetings

Article Tools

Share
Citations

Abstract

We report on a straightforward way to increase the photoluminescence enhancement of nanoemitters induced by optical nanotantennas. The nanoantennas are placed above a gold film-silica bilayer, which produces a drastic increase of the scattered radiation power and near field enhancement. We demonstrate this increase via photoluminescence enhancement using an organic emitter of low quantum efficiency, Tetraphenylporphyrin (TPP). An increase of the photoluminescence enhancement by a factor larger than three is observed compared to antennas without the reflecting-layer. In addition, we study the possibility of influencing the polarization of the light emitted by utilizing asymmetry of dimer antennas.

© 2013 OSA

1. Introduction

Optical antennas [1

1. K. B. Crozier, A. Sundaramurthy, G. S. Kino, and C. F. Quate, “Optical antennas: Resonators for local field enhancement,” J. Appl. Phys. 94, 4632 (2003) [CrossRef] .

3

3. J. A. Schuller, T. Taubner, and M. L. Brongersma, “Optical antenna thermal emitters,” Nat. Photonics 3, 658–661 (2009) [CrossRef] .

], similar to their radio frequency counterparts, capture free-space electromagnetic radiation and focus it to a small region beyond the diffraction limit. Optical antenna systems consisting of single or coupled nanoparticles have been studied extensively over the last years[4

4. S. Kühn, U. Håkanson, L. Rogobete, and V. Sandoghdar, “Enhancement of single-molecule fluorescence using a gold nanoparticle as an optical nanoantenna,” Phys. Rev. Lett. 97, 1–4 (2006) [CrossRef] .

19

19. R. M. Bakker, A. Boltasseva, Z. Liu, R. H. Pedersen, S. Gresillon, A. V. Kildishev, V. P. Drachev, and V. M. Shalaev, “Near-field excitation of nanoantenna resonance,” Opt. Express 15, 13682–13688 (2007) [CrossRef] [PubMed] .

]. It is well established that two closely spaced nanoparticles show greater field enhancement than single particles, due to the coupling of their localised surface plasmon resonances (LSPRs) [14

14. A. Sundaramurthy, K. Crozier, G. Kino, D. Fromm, P. Schuck, and W. Moerner, “Field enhancement and gap-dependent resonance in a system of two opposing tip-to-tip Au nanotriangles,” Phys. Rev. B 72, 165409 (2005) [CrossRef] .

16

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

]. The strong field enhancements provided by LSPRs can be used to enhance optical spectroscopies such as SERS [20

20. S. Nie, “Probing Single Molecules and Single Nanoparticles by surface-enhanced Raman Scattering,” Science 275, 1102–1106 (1997) [CrossRef] [PubMed] .

, 21

21. K. Kneipp, Y. Wang, H. Kneipp, L. Perelman, I. Itzkan, R. Dasari, and M. Feld, “Single Molecule Detection Using Surface-Enhanced Raman Scattering (SERS),” Phys. Rev. Lett. 78, 1667–1670 (1997) [CrossRef] .

] and multiphoton absorption [22

22. G. Volpe, M. Noack, S. S. Aćimović, C. Reinhardt, and R. Quidant, “Near-field mapping of plasmonic antennas by multiphoton absorption in poly(methyl methacrylate),” Nano Lett. 12, 4864–4868 (2012) [CrossRef] [PubMed] .

] or modify the spectral characteristics of nanoscale emitters (dyes, quantum dots...) in the vicinity of the nanoparticles [23

23. V. Giannini, A. I. Fernández-Domínguez, Y. Sonnefraud, T. Roschuk, R. Fernández-García, and S. A. Maier, “Controlling light localization and light-matter interactions with nanoplasmonics,” Small 6, 2498–2507 (2010) [CrossRef] [PubMed] .

]. In the case of nanoemitters, fluorescence enhancement can be obtained via three phenomena. On the one hand, an increase of the emitter’s radiative decay rate can be induced by the interaction between the emitter and nanoparticles resonant with the emission spectral profile [24

24. O. L. Muskens, V. Giannini, J. A. Snchez-Gil, and J. Gmez Rivas, “Strong enhancement of the radiative decay rate of emitters by single plasmonic nanoantennas,” Nano Lett. 7, 2871–2875 (2007) [CrossRef] [PubMed] .

]. On the other hand the nanoantenna can improve the transduction of the excitation light field from near field to far field [6

6. J.-H. Song, T. Atay, S. Shi, H. Urabe, and A. V. Nurmikko, “Large enhancement of fluorescence efficiency from CdSe/ZnS quantum dots induced by resonant coupling to spatially controlled surface plasmons,” Nano Lett. 5, 1557–1561 (2005) [CrossRef] [PubMed] .

, 7

7. J. N. Farahani, D. W. Pohl, H.-J. Eisler, and B. Hecht, “Single Quantum dot coupled to a scanning optical antenna: A tunable superemitter,” Phys. Rev. Lett. 95, 1–4 (2005) [CrossRef] .

, 9

9. T. Corrigan, S. Guo, R. Phaneuf, and H. Szmacinski, “Enhanced fluorescence from periodic arrays of silver nanoparticles,” J. Fluoresc. 15, 777–784 (2005) [CrossRef] [PubMed] .

, 10

10. J. S. Biteen, N. S. Lewis, H. A. Atwater, H. Mertens, and A. Polman, “Spectral tuning of plasmon-enhanced silicon quantum dot luminescence,” Appl. Phys. Lett. 88, 131109 (2006) [CrossRef] .

, 11

11. H. Mertens and A. Polman, “Plasmon-enhanced erbium luminescence,” Appl Phys. Lett. 89, 211107 (2006) [CrossRef] .

, 25

25. S. Gerber, F. Reil, U. Hohenester, T. Schlagenhaufen, J. Krenn, and A. Leitner, “Tailoring light emission properties of fluorophores by coupling to resonance-tuned metallic nanostructures,” Phys. Rev. B 75, 073404 (2007) [CrossRef] .

, 24

24. O. L. Muskens, V. Giannini, J. A. Snchez-Gil, and J. Gmez Rivas, “Strong enhancement of the radiative decay rate of emitters by single plasmonic nanoantennas,” Nano Lett. 7, 2871–2875 (2007) [CrossRef] [PubMed] .

]. Finally, nanoantennas can exert directional control on the fluorescence emission, allowing for a higher portion of the light to be emitted within the finite aperture of the collection optics [26

26. H. Aouani, O. Mahboub, N. Bonod, E. Devaux, E. Popov, H. Rigneault, T. W. Ebbesen, and J. Wenger, “Bright unidirectional fluorescence emission of molecules in a nanoaperture with plasmonic corrugations,” Nano Lett. 11, 637–644 (2011) [CrossRef] [PubMed] .

, 27

27. A. G. Curto, G. Volpe, T. H. Taminiau, M. P. Kreuzer, R. Quidant, and N. F. van Hulst, “Unidirectional emission of a quantum dot coupled to a nanoantenna,” Science 329, 930–933 (2010) [CrossRef] [PubMed] .

].

To maximize the field enhancement, a careful optimization of the optical antennas’ characteristics needs to be explored [28

28. A. Alù and N. Engheta, “Tuning the scattering response of optical nanoantennas with nanocircuit loads,” Nat. Photonics 2, 307–310 (2008) [CrossRef] .

30

30. L. Novotny, “Effective wavelength scaling for optical antennas,” Phys. Rev. Lett 98, 1–4 (2007) [CrossRef] .

]. It has been demonstrated that the field enhancement can be increased by changing the antenna dimensions, shrinking the size of the antenna feed gap, or using arrays of nanoantennas to improve the near-field coupling [2

2. P. J. Schuck, D. P. Fromm, A. Sundaramurthy, G. S. Kino, and W. E. Moerner, “Improving the mismatch between light and nanoscale objects with gold bowtie nanoantennas,” Phys. Rev. Lett. 94, 14–17 (2005) [CrossRef] .

, 31

31. W. Zhang, H. Fischer, T. Schmid, R. Zenobi, and O. J. F. Martin, “Mode-selective surface-snhanced Raman Spectroscopy Using nanofabricated plasmonic dipole antennas,” J. Phys. Chem C 113, 14672–14675 (2009) [CrossRef] .

, 32

32. Y. Chu and K. B. Crozier, “Experimental study of the interaction between localized and propagating surface plasmons,” Opt, Lett. 34, 244–246 (2009) [CrossRef] .

]. Recently studies have pointed out a very effective alternative to increase the field enhancement and the scattering cross section of metal nanoantennas via placing them on a continuous thin dielectric film on a metal underlayer. Specifically it was demonstrated that Metal-Insulator-Metal(MIM) structures working as resonators can be used to maximize the absorption in the visible regime when they are combined with nanoantennas arrays [33

33. M. G. Nielsen, D. K. Gramotnev, A. Pors, O. Albrektsen, and S. I. Bozhevolnyi, “Continuous layer gap plasmon resonators,” Opt. Express 19, 19310–19322 (2011) [CrossRef] [PubMed] .

, 34

34. M. G. Nielsen, A. Pors, O. Albrektsen, and S. I. Bozhevolnyi, “Efficient absorption of visible radiation by gap plasmon resonators,” Opt. Express 20, 13311–13319 (2012) [CrossRef] [PubMed] .

]. The addition of a reflecting underlayer provides alternative ways of tuning optical antennas by changing the dielectric layer thickness as well as increasing the near-field enhancement, achieving high quality factors [35

35. D. Gramotnev, A. Pors, M. Willatzen, and S. Bozhevolnyi, “Gap-plasmon nanoantennas and bowtie resonators,” Phys. Rev. B 85, 045434 (2012) [CrossRef] .

, 36

36. C. Ciraci, R. T. Hill, J. J. Mock, Y. Urzhumov, A. I. Fernandez-Dominguez, S. A. Maier, J. B. Pendry, A. Chilkoti, and D. R. Smith, “Probing the ultimate limits of plasmonic enhancement,” Science 337, 1072–1074 (2012) [CrossRef] [PubMed] .

]. This phenomenon can be explained by a near-field coupling between the antenna and its mirror image on the metal layer [37

37. T. J. Seok, A. Jamshidi, M. Kim, S. Dhuey, A. Lakhani, H. Choo, P. J. Schuck, S. Cabrini, A. M. Schwartzberg, J. Bokor, E. Yablonovitch, and M. C. Wu, “Radiation engineering of optical antennas for maximum field enhancement,” Nano Lett. 11, 2606–2610 (2011) [CrossRef] [PubMed] .

] and has been used to improve SERS [38

38. Y. Chu, D. Wang, W. Zhu, and K. B. Crozier, “Double resonance surface enhanced Raman scattering substrates: an intuitive coupled oscillator model,” Opt. Express 19, 14919–14928 (2011) [CrossRef] [PubMed] .

] or the directivity on optical antenna substrates [39

39. D. Wang, W. Zhu, Y. Chu, and K. B. Crozier, “High directivity optical antenna substrates for surface enhanced Raman scattering,” Adv. Mater. 24, 4376–4380 (2012) [CrossRef] [PubMed] .

], allowing for single molecular detection [40

40. A. Ahmed and R. Gordon, “Single molecule directivity enhanced Raman scattering using nanoantennas,” Nano Lett. 12, 2625–2630 (2012) [CrossRef] [PubMed] .

]. Also, Gong et al. [41

41. Yiyang Gong, Selçuk Yerci, Rui Li, Luca Dal Negro, and Jelena Vuckovic, Enhanced light emission from erbium doped silicon nitride in plasmonic metal-insulator-metal structures. Opt. Express 17, (23)20642–20650 (2009) [CrossRef] [PubMed] .

] show an enhancement in the emission intensity of Erbium-doped SiN placed in Metal-Insulator-Metal plasmonic cavities. However, none of these articles have investigated the possibility to use this concept to improve the radiation properties of single nanoantennas in terms of enhancement of the fluorescence of organic nanoemitters.

In this article, we investigate both theoretically and experimentally a plasmonic resonant system consisting of gold dimer nanoantennas separated by a thin dielectric layer of SiO2 from a gold metal underlayer. The nanoemitter chosen for our study is meso-Tetraphenylporphyrin (TPP), an organic dye which presents two well-separated emission peaks at 650 and 750 nm, as shown in Fig. 1(c) [42

42. R. Bonnett, D. J. McGarvey, A. Harriman, E. J. Land, T. G. Truscott, and U.-J. Winfield, “Photophysical properties of meso-tetraphenylporphyrin and some meso-tetra(hydroxyphenyl)porphyrins,” Photochem. Photobiol. 48, 271–276 (1988) [CrossRef] [PubMed] .

]. We demonstrate that the addition of the metal layer in the nanoantenna fabrication leads to an increased scattering cross section and field enhancement. This is accompanied by an increase of photoluminescence enhancement. The asymmetry of the dimer leads to two LSPRs in different wavelength ranges along the two perpendicular polarisations. Those two spectrally separated LSPRs enhance selectively the emission bands of TPP depending on the polarisation.

Fig. 1 (a) Experimental setup for TPP fluorescence measurement. The excitation laser at a wavelength of 405 nm is coupled into a 40× reflective objective that focuses the laser beam on the sample and collects the emitted light. The fluorescence light is filtered using a dichroic mirror (DM) and a high pass filter (HP) at 420 nm in order to cut off the incident light scattered from the sample. The beam can be either sent to a spectrometer (SPEC) combined with a CCD camera, or to a pair of detectors. In the latter case, a 50 μm-pinhole PH selects the fluorescent light coming from the focal spot only. Lens L2 collimates the light transmitted through PH, which is then directed to a polarising beam splitter (PBS) that splits the two polarization components. Finally the light is focused on two APDs (avalanche photodiode) detectors that collect simultaneously both polarizations along x and y axes. (b) Schematic sample cross section. A film of TPP embedded in a PMMA matrix is deposited on top of the antennas at a thickness approximately equal to that of the antennas (40 nm). (c) Measured absorption and photoluminescence (PL) emission spectra from a film of TPP into a PMMA host matrix.

2. Methods

Our study uses glass substrates covered by a 100 nm thick gold layer, further capped by a continuous 25 nm SiO2 film (nd = 1.45). The nanoantennas were nanofabricated on top of the SiO2 film, and are 40 nm-thick gold dimers composed of two opposing long arms separated by a 30 nm gap, as illustrated in Fig. 1(b). The structures were fabricated by electron beam lithography (Elonix 100KV EBL system) with the process described in [43

43. M. Rahmani, D. Y. Lei, V. Giannini, B. Lukiyanchuk, M. Ranjbar, T. Y. F. Liew, M. Hong, and S. A. Maier, “Subgroup decomposition of plasmonic resonances in hybrid oligomers: Modeling the resonance lineshape,” Nano Lett. 12, 2101–2106 (2012) [CrossRef] [PubMed] .

]. The antennas were fabricated in arrays at a separation of 4μm allowing to measure the optical response of a single antenna. The emitting layer is produced by spin-coating a film of TPP-doped PMMA film on the sample, at a thickness of approximately 40 nm. The weight concentration ratio PMMA/TPP is chosen to be 75 in order to maximize the TPP film fluorescence. Since TPP possesses a low quantum yield (<20%) [42

42. R. Bonnett, D. J. McGarvey, A. Harriman, E. J. Land, T. G. Truscott, and U.-J. Winfield, “Photophysical properties of meso-tetraphenylporphyrin and some meso-tetra(hydroxyphenyl)porphyrins,” Photochem. Photobiol. 48, 271–276 (1988) [CrossRef] [PubMed] .

], it is an ideal candidate for photoluminescence enhancement using plasmonic nanostructures [44

44. V. Giannini, A. I. Fernández-Domínguez, S. C. Heck, and S. a. Maier, “Plasmonic nanoantennas: fundamentals and their use in controlling the radiative properties of nanoemitters,” Chem. Rev. 111, 3888–3912 (2011) [CrossRef] [PubMed] .

].

Figure 1(a) presents a schematic diagram of the experimental setup. The excitation laser is set at a wavelength of 405 nm to match the absorption band of TPP [Fig. 1(c)]. A 40×, NA=0.6 microscope objective is used to focus the laser beam on the sample and collect the emitted light from the sample. The fluorescent light is filtered in order to cut off the incident light scattered from the sample. The fluorescent light can be sent to a spectrometer or to a polarizing beam splitter that splits the two polarization components, which are collected independently on two APDs (avalanche photodiode) detectors. The scattering cross sections of the nanoantennas were measured on individual nanoantennas using dark-field spectroscopy with a polarization-adjustable white-light illumination at an incident angle θ = 60° with respect to the normal of the sample surface, as described elsewhere [45

45. D. Y. Lei, A. I. Fernndez-Domnguez, Y. Sonnefraud, K. Appavoo, R. F. Haglund, J. B. Pendry, and S. A. Maier, “Revealing plasmonic gap modes in particle-on-film systems using dark-field spectroscopy,” ACS. Nano. 6, 1380–1386 (2012) [CrossRef] [PubMed] .

]. Numerical simulations were performed to evaluate the scattering cross sections of the antennas as well as their near-field enhancement and the radiated power of an emitter in the presence of the antennas. The simulations were performed using the commercial 3D full-wave electromagnetic wave solver Lumerical FDTD Solutions, at similar conditions to the measurements using the experimental sample geometries. The optical constants were obtained by fitting the values found in [46

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

] to a multi-coefficient model.

3. Results and discussion

We firstly describe and characterize the antenna system used in our study. The nanoantenna system is not yet covered with the dye-doped layer, and we choose a nanoantenna composed of two opposing 75 nm long arms (elongated disks) with a 30 nm gap. Figure 2(a) shows a simulation of the near-field enhancement as a function of the excitation wavelength by spatially integrating the field intensity at every point in the surrounding antenna volume with and without the reflecting layer. Since the confocal setup probes a zone limited by diffraction, we choose to integrate the near-field intensity in a volume comparable to the probing area of excitation (300 nm × 200 nm × 100 nm). This allows us to estimate the average near-field enhancement on the TPP molecules, which are randomly spatially distributed and oriented.

Fig. 2 Effect of a gold underlayer on the antenna properties. The nanoantennas are composed of two 75 nm long arms with a 30 nm gap on a glass substrate and surrounded with air (n=1). (a) Comparison between the near field (NF) enhacement, integrated over a volume of 300 nm × 200 nm × 100 nm surrounding the antenna, of dimer antennas placed on a glass substrate with (black line) and without (red line) gold underlayer. For this comparison, the polarization is selected parallel to the antenna axis, X-pol. Dotted red line: antenna with ≈ 95 nm long arms, without gold layer, to match the resonance at 655 nm. Inset: simulated power radiated by a dipole placed at the antenna gap for different values of SiO2 thickness. The dipole is placed at the center of the gap cavity with polarization parallel to the antenna main axis in order to maximize the coupling. (b) Comparison between the simulated scattering cross section (continuous lines) and dark field scattering (dotted lines), for an incident polarisation along the main axis of the antenna. Experimental and simulated data in black refers to dimer antennas placed on a glass substrate and red data to dimmer antennas without gold underlayer. Inset: scanning electron microscope (SEM) image of one nanoantenna being considered.

Figure 2(b) shows a comparison of the simulated scattering cross section (solid lines) and the dark field scattering of the antennas (dotted lines) placed on a glass substrate with (black) and without (red) gold underlayer. For these and all subsequent simulations, the PMMA layer is not taken into account because the measurement of the scattering cross sections of the antennas after deposition of the PMMA/TPP layer only exhibited a minor shift of the resonances (≈10 nm). Spectra are normalised relatively to the intensity of the resonance parallel to the dimmer axis for the case of using a gold underlayer. Far field projections (not shown) of the light emitted by a dipole in the situation described in Figure (2)a show that the underlayer does not change the radiation profile: the photoluminescence enhancement seen is not due to a beaming effect. For this reason, it is not necessary to take into account the finite NA of the microscope objectives used in the simulations. Hence we always estimate the scattering cross sections of the nanoantennas by integrating over the full 4π space. We observe a good agreement between experiment and simulation, both demonstrating that using a gold underlayer the scattering of the antenna increases by a factor up to 4 in the current configuration.

We then evaluate the effect of the gold underlayer on the photoluminescence (PL) enhancement of the TPP emitters placed on the antenna vicinity. Figure 3(a) shows the spectral overlap between the emission band of TPP and the simulated near-field resonances for the polarization along the main axis of the dimer with and without the gold underlayer. In both cases, the near-field resonances predominantly match the first emission peak at 640–680 nm. We thus filter the PL in this wavelength range to maximize the intensity contrast Fig. 3(b). The fluorescence comparison shows that antennas without the Au under layer induces a 10% PL enhancement while the antennas with the gold underlayer reach up to 50%, as highlighted on the profiles on Fig. 3(b–d). This result is in good agreement with the values predicted by the simulations as discussed previously. The ratio of the enhancements is slightly higher than what is expected from the near field integrations discussed in Fig. 2(a), probably because the overlap between the resonance of the nanoantenna and the emission peak of TPP is stronger in the case with the reflective gold layer. Note while, the total maximum enhancement seen is modest, this is due to the fact that the radiation collected is integrated over the whole confocal volume, which contains many dyes, randomly positioned and oriented - only the ones in the centre of the gap experience for optimum enhancement.

Fig. 3 (a) Spectral overlap between the emission band of TPP and simulated NF resonances with and without gold underlayer, for the polarization parallel to the dimer main axis. (b) (resp. (c)) Photoluminescence intensity around single resonant antennas for polarization of the detected light parallel to the antenna axis without (resp. with) the gold underlayer (scale bars 2 μm). Only light in the range 640–680 nm is collected, which corresponds to the first emission peak of TPP. The PL intensity I is normalized to the intensity measured away from the nanoantennas, I0. Bottom: horizontal profiles as indicated on the images above. The antennas without the Au underlayer induced a 10% PL enhancement, while antennas with the gold underlayer reach up to 50% PL enhancement.

Furthermore, we study the effect of polarization for the case of a dimmer antenna with the reflecting underlayer. Figure 4 shows the two resonances sustained by a gold dimer for both parallel and perpendicular polarizations with respect to the dimmer axis. For this study, the dimer antennas used were chosen with a larger length in order to have the main resonance along the X axis matching the low energy emission peak of TPP at 700–740 nm. The resonance along the X axis is much more intense than the Y-axis resonance due to the strong coupling between the particles as reflected also in the near-field profile [Fig. 4(c)]. Dark field measurement and scattering simulation in Fig. 4(a) clearly show the difference in intensities and the spectral separation between both resonances.

Fig. 4 Influence of the polarization on the scattering of a gold dimer consisting of two elongated disks with the dimensions 105×60×40 nm3 (long axis × short axis × thickness) separated by a 30 nm gap. (a) Dark field spectra (solid lines) and simulation of the scattering cross section (dotted lines) of the nanoantenna for X and Y polarizations In all cases the values are normalised to the value at the peak for the X polarisation. Inset: SEM image of the gold antenna considered (scale bar: 100 nm). (b) Near field intensity distribution of the antenna for illumination of polarization perpendicular (Y direction) and (c) parallel (X direction) to the antenna axis.

Figure 5(a) compares the emission band of TPP and the simulated near-field resonances for an excitation along the main axis of the dimer (X-polarised) and perpendicular to it (Y-polarised). There is a good overlap between the low energy peak at 700–740 nm and the X-resonance and a partial overlap of the Y-resonance with the high energy peak at 640–680 nm. In addition, a small contribution from the X-resonance tail overlaps with the high energy peak. The spectrum of PL of the TPP is acquired without specific filtering, on the antennas and away from them. The results, as shown in Fig. 5(b), show a PL enhancement in all the emission ranges, which is more pronounced at the low energy emission peak, with a 25% increase in the peak intensity. This is in agreement with the overlap presented in Fig. 5(a). The enhancement is 5% for the high energy peak, attributed to the smaller contribution from both resonances in this spectral region at 640–680 nm. Figure 5(c) illustrates the PL enhancement difference for both peaks by imaging three identical nanoantennas, either selecting only the first peak (top) or only the second (bottom).

Fig. 5 (a) Spectral overlap between the emission bands of TPP (blue curve) and the simulated near field resonances for the X and Y polarizations, black curve and red curve respectively. The PL collected is filtered either in the area highlighted in blue (640–680 nm) or in green (700–740 nm). (b) TPP emission spectra collected from one antenna (black curve) and on the plain TPP film (red) without a filter. (c) Filtered photoluminescence intensity images around single resonant antennas: filtering for the first emission peak at 640–680 nm (top) and for the second emission peak at 700–740 nm (bottom). Note that here no particular polarisation is selected for the PL. Scale bars: 2μm.

We finish our discussion by analysing the effect of both resonances independently and experimentally test the overlap discussed in Fig. 5(a). To do so, we collect independently the two polarization components of the PL emitted, as described in Fig. 1. Figure 6(a) shows the PL enhancement in the X polarization. In this case, the low energy peak is enhanced up to 80% whereas the high energy peak is enhanced up to 20%. The ratio between the two enhancements is in a reasonable agreement with the predicted overlap between the near field resonance in the X-axis resonance and the two TPP emission peaks. Similarly, Fig. 6(b) shows that for the polarization perpendicular to the antenna axis, the TPP emission peak around 640–680 nm is more enhanced than the low energy peak, which is again consistent with the magnitude of the field enhancement provided by the nanoantenna for this polarisation. These observations support that doubly resonant systems, like gold dimers, can be used to selectively influence the polarization of emitted light in a specific wavelength range.

Fig. 6 Study of the influence of the nanoantenna on the polarisation properties of the PL emitted. (a) Top: PL intensity around single nanoantennas for polarization of the detected light parallel to the nanoantenna axis, filtered at around 640–680 nm and 700–740 nm. Scale bars: 1μm. Bottom: horizontal profiles comparing the PL of the two emission peaks for X-polarised detected light. The TPP emission peak in the 700–740 nm range is preferentially enhanced over the peak at 640–680 nm. The inset is an SEM image of the antenna considered, scale bar 100 nm. (b) PL intensity for polarization of the detected light perpendicular to the antenna axis. The peak around 640–680 nm is preferentially enhanced in this case.

4. Conclusions

We have demonstrated that the addition of a gold underlayer to the fabrication of nanoantennas can improves their properties, by offering new possibilities of resonance tuning by means of controlling the spacer thickness and increasing their scattered radiation power and near-field enhancement. These in turn increase the photoluminescence enhancement induced by the antenna on a low efficiency light emitter such as TPP. In addition, this improvement enhances the intensity of the two resonances associated with the perpendicular light polarizations existing in a gold dimer, allowing to measure their influence in a specific wavelength of the dye emission. Such a system presents a way to selectively influence the polarization of emitted light in organic dyes with multiple emission peaks.

Acknowledgments

This work is supported in part by the UK Engineering and Physical Sciences Research Council (EPSRC) and Nano-Sci Era Nanospec. Y.S. acknowledges funding from the Leverhulme Trust(U.K). M.R acknowledges Data Storage Institute of Singapore, (A*STAR) Agency for Science Technology and Research.

References and links

1.

K. B. Crozier, A. Sundaramurthy, G. S. Kino, and C. F. Quate, “Optical antennas: Resonators for local field enhancement,” J. Appl. Phys. 94, 4632 (2003) [CrossRef] .

2.

P. J. Schuck, D. P. Fromm, A. Sundaramurthy, G. S. Kino, and W. E. Moerner, “Improving the mismatch between light and nanoscale objects with gold bowtie nanoantennas,” Phys. Rev. Lett. 94, 14–17 (2005) [CrossRef] .

3.

J. A. Schuller, T. Taubner, and M. L. Brongersma, “Optical antenna thermal emitters,” Nat. Photonics 3, 658–661 (2009) [CrossRef] .

4.

S. Kühn, U. Håkanson, L. Rogobete, and V. Sandoghdar, “Enhancement of single-molecule fluorescence using a gold nanoparticle as an optical nanoantenna,” Phys. Rev. Lett. 97, 1–4 (2006) [CrossRef] .

5.

H. Ditlbacher, J. R. Krenn, N. Felidj, B. Lamprecht, G. Schider, M. Salerno, A. Leitner, and F. R. Aussenegg, “Fluorescence imaging of surface plasmon fields,” Appl. Phys. Lett. 80, 404 (2002) [CrossRef] .

6.

J.-H. Song, T. Atay, S. Shi, H. Urabe, and A. V. Nurmikko, “Large enhancement of fluorescence efficiency from CdSe/ZnS quantum dots induced by resonant coupling to spatially controlled surface plasmons,” Nano Lett. 5, 1557–1561 (2005) [CrossRef] [PubMed] .

7.

J. N. Farahani, D. W. Pohl, H.-J. Eisler, and B. Hecht, “Single Quantum dot coupled to a scanning optical antenna: A tunable superemitter,” Phys. Rev. Lett. 95, 1–4 (2005) [CrossRef] .

8.

M. Rahmani, T. Tahmasebi, Y. Lin, B. Lukiyanchuk, T. Y. F. Liew, and M. H. Hong, “Influence of plasmon destructive interferences on optical properties of gold planar quadrumers,” Nanotechnology 22, 245204 (2011) [CrossRef] [PubMed] .

9.

T. Corrigan, S. Guo, R. Phaneuf, and H. Szmacinski, “Enhanced fluorescence from periodic arrays of silver nanoparticles,” J. Fluoresc. 15, 777–784 (2005) [CrossRef] [PubMed] .

10.

J. S. Biteen, N. S. Lewis, H. A. Atwater, H. Mertens, and A. Polman, “Spectral tuning of plasmon-enhanced silicon quantum dot luminescence,” Appl. Phys. Lett. 88, 131109 (2006) [CrossRef] .

11.

H. Mertens and A. Polman, “Plasmon-enhanced erbium luminescence,” Appl Phys. Lett. 89, 211107 (2006) [CrossRef] .

12.

W. Rechberger, A. Hohenau, A. Leitner, J. Krenn, B. Lamprecht, and F. Aussenegg, “Optical properties of two interacting gold nanoparticles,” Opt. Commun. 220, 137–141 (2003) [CrossRef] .

13.

K.-H. Su, Q.-H. Wei, X. Zhang, J. J. Mock, D. R. Smith, and S. Schultz, “Interparticle Coupling effects on plasmon resonances of nanogold Particles,” Nano Lett. 3, 1087–1090 (2003) [CrossRef] .

14.

A. Sundaramurthy, K. Crozier, G. Kino, D. Fromm, P. Schuck, and W. Moerner, “Field enhancement and gap-dependent resonance in a system of two opposing tip-to-tip Au nanotriangles,” Phys. Rev. B 72, 165409 (2005) [CrossRef] .

15.

P. Mühlschlegel, H.-J. Eisler, O. J. F. Martin, B. Hecht, and D. W. Pohl, “Resonant optical antennas,” Science 308, 1607–1609 (2005) [CrossRef] [PubMed] .

16.

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

17.

L. Rogobete, F. Kaminski, M. Agio, and V. Sandoghdar, “Design of plasmonic nanoantennae for enhancing spontaneous emission,” Opt. Lett. 32, 1623–1625 (2007) [CrossRef] [PubMed] .

18.

P. K. Jain and M. A. El-Sayed, “Universal scaling of plasmon coupling in metal nanostructures: extension from particle pairs to nanoshells,” Nano Lett. 7, 2854–2858 (2007) [CrossRef] [PubMed] .

19.

R. M. Bakker, A. Boltasseva, Z. Liu, R. H. Pedersen, S. Gresillon, A. V. Kildishev, V. P. Drachev, and V. M. Shalaev, “Near-field excitation of nanoantenna resonance,” Opt. Express 15, 13682–13688 (2007) [CrossRef] [PubMed] .

20.

S. Nie, “Probing Single Molecules and Single Nanoparticles by surface-enhanced Raman Scattering,” Science 275, 1102–1106 (1997) [CrossRef] [PubMed] .

21.

K. Kneipp, Y. Wang, H. Kneipp, L. Perelman, I. Itzkan, R. Dasari, and M. Feld, “Single Molecule Detection Using Surface-Enhanced Raman Scattering (SERS),” Phys. Rev. Lett. 78, 1667–1670 (1997) [CrossRef] .

22.

G. Volpe, M. Noack, S. S. Aćimović, C. Reinhardt, and R. Quidant, “Near-field mapping of plasmonic antennas by multiphoton absorption in poly(methyl methacrylate),” Nano Lett. 12, 4864–4868 (2012) [CrossRef] [PubMed] .

23.

V. Giannini, A. I. Fernández-Domínguez, Y. Sonnefraud, T. Roschuk, R. Fernández-García, and S. A. Maier, “Controlling light localization and light-matter interactions with nanoplasmonics,” Small 6, 2498–2507 (2010) [CrossRef] [PubMed] .

24.

O. L. Muskens, V. Giannini, J. A. Snchez-Gil, and J. Gmez Rivas, “Strong enhancement of the radiative decay rate of emitters by single plasmonic nanoantennas,” Nano Lett. 7, 2871–2875 (2007) [CrossRef] [PubMed] .

25.

S. Gerber, F. Reil, U. Hohenester, T. Schlagenhaufen, J. Krenn, and A. Leitner, “Tailoring light emission properties of fluorophores by coupling to resonance-tuned metallic nanostructures,” Phys. Rev. B 75, 073404 (2007) [CrossRef] .

26.

H. Aouani, O. Mahboub, N. Bonod, E. Devaux, E. Popov, H. Rigneault, T. W. Ebbesen, and J. Wenger, “Bright unidirectional fluorescence emission of molecules in a nanoaperture with plasmonic corrugations,” Nano Lett. 11, 637–644 (2011) [CrossRef] [PubMed] .

27.

A. G. Curto, G. Volpe, T. H. Taminiau, M. P. Kreuzer, R. Quidant, and N. F. van Hulst, “Unidirectional emission of a quantum dot coupled to a nanoantenna,” Science 329, 930–933 (2010) [CrossRef] [PubMed] .

28.

A. Alù and N. Engheta, “Tuning the scattering response of optical nanoantennas with nanocircuit loads,” Nat. Photonics 2, 307–310 (2008) [CrossRef] .

29.

J. Merlein, M. Kahl, A. Zuschlag, A. Sell, A. Halm, J. Boneberg, P. Leiderer, A. Leitenstorfer, and R. Bratschitsch, “Nanomechanical control of an optical antenna,” Nat. Photonics 2, 230–233 (2008) [CrossRef] .

30.

L. Novotny, “Effective wavelength scaling for optical antennas,” Phys. Rev. Lett 98, 1–4 (2007) [CrossRef] .

31.

W. Zhang, H. Fischer, T. Schmid, R. Zenobi, and O. J. F. Martin, “Mode-selective surface-snhanced Raman Spectroscopy Using nanofabricated plasmonic dipole antennas,” J. Phys. Chem C 113, 14672–14675 (2009) [CrossRef] .

32.

Y. Chu and K. B. Crozier, “Experimental study of the interaction between localized and propagating surface plasmons,” Opt, Lett. 34, 244–246 (2009) [CrossRef] .

33.

M. G. Nielsen, D. K. Gramotnev, A. Pors, O. Albrektsen, and S. I. Bozhevolnyi, “Continuous layer gap plasmon resonators,” Opt. Express 19, 19310–19322 (2011) [CrossRef] [PubMed] .

34.

M. G. Nielsen, A. Pors, O. Albrektsen, and S. I. Bozhevolnyi, “Efficient absorption of visible radiation by gap plasmon resonators,” Opt. Express 20, 13311–13319 (2012) [CrossRef] [PubMed] .

35.

D. Gramotnev, A. Pors, M. Willatzen, and S. Bozhevolnyi, “Gap-plasmon nanoantennas and bowtie resonators,” Phys. Rev. B 85, 045434 (2012) [CrossRef] .

36.

C. Ciraci, R. T. Hill, J. J. Mock, Y. Urzhumov, A. I. Fernandez-Dominguez, S. A. Maier, J. B. Pendry, A. Chilkoti, and D. R. Smith, “Probing the ultimate limits of plasmonic enhancement,” Science 337, 1072–1074 (2012) [CrossRef] [PubMed] .

37.

T. J. Seok, A. Jamshidi, M. Kim, S. Dhuey, A. Lakhani, H. Choo, P. J. Schuck, S. Cabrini, A. M. Schwartzberg, J. Bokor, E. Yablonovitch, and M. C. Wu, “Radiation engineering of optical antennas for maximum field enhancement,” Nano Lett. 11, 2606–2610 (2011) [CrossRef] [PubMed] .

38.

Y. Chu, D. Wang, W. Zhu, and K. B. Crozier, “Double resonance surface enhanced Raman scattering substrates: an intuitive coupled oscillator model,” Opt. Express 19, 14919–14928 (2011) [CrossRef] [PubMed] .

39.

D. Wang, W. Zhu, Y. Chu, and K. B. Crozier, “High directivity optical antenna substrates for surface enhanced Raman scattering,” Adv. Mater. 24, 4376–4380 (2012) [CrossRef] [PubMed] .

40.

A. Ahmed and R. Gordon, “Single molecule directivity enhanced Raman scattering using nanoantennas,” Nano Lett. 12, 2625–2630 (2012) [CrossRef] [PubMed] .

41.

Yiyang Gong, Selçuk Yerci, Rui Li, Luca Dal Negro, and Jelena Vuckovic, Enhanced light emission from erbium doped silicon nitride in plasmonic metal-insulator-metal structures. Opt. Express 17, (23)20642–20650 (2009) [CrossRef] [PubMed] .

42.

R. Bonnett, D. J. McGarvey, A. Harriman, E. J. Land, T. G. Truscott, and U.-J. Winfield, “Photophysical properties of meso-tetraphenylporphyrin and some meso-tetra(hydroxyphenyl)porphyrins,” Photochem. Photobiol. 48, 271–276 (1988) [CrossRef] [PubMed] .

43.

M. Rahmani, D. Y. Lei, V. Giannini, B. Lukiyanchuk, M. Ranjbar, T. Y. F. Liew, M. Hong, and S. A. Maier, “Subgroup decomposition of plasmonic resonances in hybrid oligomers: Modeling the resonance lineshape,” Nano Lett. 12, 2101–2106 (2012) [CrossRef] [PubMed] .

44.

V. Giannini, A. I. Fernández-Domínguez, S. C. Heck, and S. a. Maier, “Plasmonic nanoantennas: fundamentals and their use in controlling the radiative properties of nanoemitters,” Chem. Rev. 111, 3888–3912 (2011) [CrossRef] [PubMed] .

45.

D. Y. Lei, A. I. Fernndez-Domnguez, Y. Sonnefraud, K. Appavoo, R. F. Haglund, J. B. Pendry, and S. A. Maier, “Revealing plasmonic gap modes in particle-on-film systems using dark-field spectroscopy,” ACS. Nano. 6, 1380–1386 (2012) [CrossRef] [PubMed] .

46.

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

47.

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

48.

A. Kinkhabwala, Z. Yu, S. Fan, Y. Avlasevich, K. Müllen, and W. E. Moerner, “Large single-molecule fluorescence enhancements produced by a bowtie nanoantenna,” Nat. Photonics 3, 654–657 (2009) [CrossRef] .

OCIS Codes
(170.6280) Medical optics and biotechnology : Spectroscopy, fluorescence and luminescence
(180.0180) Microscopy : Microscopy
(240.6680) Optics at surfaces : Surface plasmons

ToC Category:
Optics at Surfaces

History
Original Manuscript: February 14, 2013
Revised Manuscript: March 13, 2013
Manuscript Accepted: March 22, 2013
Published: May 15, 2013

Virtual Issues
Vol. 8, Iss. 6 Virtual Journal for Biomedical Optics

Citation
Roberto Fernandez-Garcia, Mohsen Rahmani, Minghui Hong, Stefan A. Maier, and Yannick Sonnefraud, "Use of a gold reflecting-layer in optical antenna substrates for increase of photoluminescence enhancement," Opt. Express 21, 12552-12561 (2013)
http://www.opticsinfobase.org/vjbo/abstract.cfm?URI=oe-21-10-12552


Sort:  Author  |  Year  |  Journal  |  Reset  

References

  1. K. B. Crozier, A. Sundaramurthy, G. S. Kino, and C. F. Quate, “Optical antennas: Resonators for local field enhancement,” J. Appl. Phys.94, 4632 (2003). [CrossRef]
  2. P. J. Schuck, D. P. Fromm, A. Sundaramurthy, G. S. Kino, and W. E. Moerner, “Improving the mismatch between light and nanoscale objects with gold bowtie nanoantennas,” Phys. Rev. Lett.94, 14–17 (2005). [CrossRef]
  3. J. A. Schuller, T. Taubner, and M. L. Brongersma, “Optical antenna thermal emitters,” Nat. Photonics3, 658–661 (2009). [CrossRef]
  4. S. Kühn, U. Håkanson, L. Rogobete, and V. Sandoghdar, “Enhancement of single-molecule fluorescence using a gold nanoparticle as an optical nanoantenna,” Phys. Rev. Lett.97, 1–4 (2006). [CrossRef]
  5. H. Ditlbacher, J. R. Krenn, N. Felidj, B. Lamprecht, G. Schider, M. Salerno, A. Leitner, and F. R. Aussenegg, “Fluorescence imaging of surface plasmon fields,” Appl. Phys. Lett.80, 404 (2002). [CrossRef]
  6. J.-H. Song, T. Atay, S. Shi, H. Urabe, and A. V. Nurmikko, “Large enhancement of fluorescence efficiency from CdSe/ZnS quantum dots induced by resonant coupling to spatially controlled surface plasmons,” Nano Lett.5, 1557–1561 (2005). [CrossRef] [PubMed]
  7. J. N. Farahani, D. W. Pohl, H.-J. Eisler, and B. Hecht, “Single Quantum dot coupled to a scanning optical antenna: A tunable superemitter,” Phys. Rev. Lett.95, 1–4 (2005). [CrossRef]
  8. M. Rahmani, T. Tahmasebi, Y. Lin, B. Lukiyanchuk, T. Y. F. Liew, and M. H. Hong, “Influence of plasmon destructive interferences on optical properties of gold planar quadrumers,” Nanotechnology22, 245204 (2011). [CrossRef] [PubMed]
  9. T. Corrigan, S. Guo, R. Phaneuf, and H. Szmacinski, “Enhanced fluorescence from periodic arrays of silver nanoparticles,” J. Fluoresc.15, 777–784 (2005). [CrossRef] [PubMed]
  10. J. S. Biteen, N. S. Lewis, H. A. Atwater, H. Mertens, and A. Polman, “Spectral tuning of plasmon-enhanced silicon quantum dot luminescence,” Appl. Phys. Lett.88, 131109 (2006). [CrossRef]
  11. H. Mertens and A. Polman, “Plasmon-enhanced erbium luminescence,” Appl Phys. Lett.89, 211107 (2006). [CrossRef]
  12. W. Rechberger, A. Hohenau, A. Leitner, J. Krenn, B. Lamprecht, and F. Aussenegg, “Optical properties of two interacting gold nanoparticles,” Opt. Commun.220, 137–141 (2003). [CrossRef]
  13. K.-H. Su, Q.-H. Wei, X. Zhang, J. J. Mock, D. R. Smith, and S. Schultz, “Interparticle Coupling effects on plasmon resonances of nanogold Particles,” Nano Lett.3, 1087–1090 (2003). [CrossRef]
  14. A. Sundaramurthy, K. Crozier, G. Kino, D. Fromm, P. Schuck, and W. Moerner, “Field enhancement and gap-dependent resonance in a system of two opposing tip-to-tip Au nanotriangles,” Phys. Rev. B72, 165409 (2005). [CrossRef]
  15. P. Mühlschlegel, H.-J. Eisler, O. J. F. Martin, B. Hecht, and D. W. Pohl, “Resonant optical antennas,” Science308, 1607–1609 (2005). [CrossRef] [PubMed]
  16. E. Cubukcu, E. a. Kort, K. B. Crozier, and F. Capasso, “Plasmonic laser antenna,” Appl. Phys. Lett.89, 093120 (2006). [CrossRef]
  17. L. Rogobete, F. Kaminski, M. Agio, and V. Sandoghdar, “Design of plasmonic nanoantennae for enhancing spontaneous emission,” Opt. Lett.32, 1623–1625 (2007). [CrossRef] [PubMed]
  18. P. K. Jain and M. A. El-Sayed, “Universal scaling of plasmon coupling in metal nanostructures: extension from particle pairs to nanoshells,” Nano Lett.7, 2854–2858 (2007). [CrossRef] [PubMed]
  19. R. M. Bakker, A. Boltasseva, Z. Liu, R. H. Pedersen, S. Gresillon, A. V. Kildishev, V. P. Drachev, and V. M. Shalaev, “Near-field excitation of nanoantenna resonance,” Opt. Express15, 13682–13688 (2007). [CrossRef] [PubMed]
  20. S. Nie, “Probing Single Molecules and Single Nanoparticles by surface-enhanced Raman Scattering,” Science275, 1102–1106 (1997). [CrossRef] [PubMed]
  21. K. Kneipp, Y. Wang, H. Kneipp, L. Perelman, I. Itzkan, R. Dasari, and M. Feld, “Single Molecule Detection Using Surface-Enhanced Raman Scattering (SERS),” Phys. Rev. Lett.78, 1667–1670 (1997). [CrossRef]
  22. G. Volpe, M. Noack, S. S. Aćimović, C. Reinhardt, and R. Quidant, “Near-field mapping of plasmonic antennas by multiphoton absorption in poly(methyl methacrylate),” Nano Lett.12, 4864–4868 (2012). [CrossRef] [PubMed]
  23. V. Giannini, A. I. Fernández-Domínguez, Y. Sonnefraud, T. Roschuk, R. Fernández-García, and S. A. Maier, “Controlling light localization and light-matter interactions with nanoplasmonics,” Small6, 2498–2507 (2010). [CrossRef] [PubMed]
  24. O. L. Muskens, V. Giannini, J. A. Snchez-Gil, and J. Gmez Rivas, “Strong enhancement of the radiative decay rate of emitters by single plasmonic nanoantennas,” Nano Lett.7, 2871–2875 (2007). [CrossRef] [PubMed]
  25. S. Gerber, F. Reil, U. Hohenester, T. Schlagenhaufen, J. Krenn, and A. Leitner, “Tailoring light emission properties of fluorophores by coupling to resonance-tuned metallic nanostructures,” Phys. Rev. B75, 073404 (2007). [CrossRef]
  26. H. Aouani, O. Mahboub, N. Bonod, E. Devaux, E. Popov, H. Rigneault, T. W. Ebbesen, and J. Wenger, “Bright unidirectional fluorescence emission of molecules in a nanoaperture with plasmonic corrugations,” Nano Lett.11, 637–644 (2011). [CrossRef] [PubMed]
  27. A. G. Curto, G. Volpe, T. H. Taminiau, M. P. Kreuzer, R. Quidant, and N. F. van Hulst, “Unidirectional emission of a quantum dot coupled to a nanoantenna,” Science329, 930–933 (2010). [CrossRef] [PubMed]
  28. A. Alù and N. Engheta, “Tuning the scattering response of optical nanoantennas with nanocircuit loads,” Nat. Photonics2, 307–310 (2008). [CrossRef]
  29. J. Merlein, M. Kahl, A. Zuschlag, A. Sell, A. Halm, J. Boneberg, P. Leiderer, A. Leitenstorfer, and R. Bratschitsch, “Nanomechanical control of an optical antenna,” Nat. Photonics2, 230–233 (2008). [CrossRef]
  30. L. Novotny, “Effective wavelength scaling for optical antennas,” Phys. Rev. Lett98, 1–4 (2007). [CrossRef]
  31. W. Zhang, H. Fischer, T. Schmid, R. Zenobi, and O. J. F. Martin, “Mode-selective surface-snhanced Raman Spectroscopy Using nanofabricated plasmonic dipole antennas,” J. Phys. Chem C113, 14672–14675 (2009). [CrossRef]
  32. Y. Chu and K. B. Crozier, “Experimental study of the interaction between localized and propagating surface plasmons,” Opt, Lett.34, 244–246 (2009). [CrossRef]
  33. M. G. Nielsen, D. K. Gramotnev, A. Pors, O. Albrektsen, and S. I. Bozhevolnyi, “Continuous layer gap plasmon resonators,” Opt. Express19, 19310–19322 (2011). [CrossRef] [PubMed]
  34. M. G. Nielsen, A. Pors, O. Albrektsen, and S. I. Bozhevolnyi, “Efficient absorption of visible radiation by gap plasmon resonators,” Opt. Express20, 13311–13319 (2012). [CrossRef] [PubMed]
  35. D. Gramotnev, A. Pors, M. Willatzen, and S. Bozhevolnyi, “Gap-plasmon nanoantennas and bowtie resonators,” Phys. Rev. B85, 045434 (2012). [CrossRef]
  36. C. Ciraci, R. T. Hill, J. J. Mock, Y. Urzhumov, A. I. Fernandez-Dominguez, S. A. Maier, J. B. Pendry, A. Chilkoti, and D. R. Smith, “Probing the ultimate limits of plasmonic enhancement,” Science337, 1072–1074 (2012). [CrossRef] [PubMed]
  37. T. J. Seok, A. Jamshidi, M. Kim, S. Dhuey, A. Lakhani, H. Choo, P. J. Schuck, S. Cabrini, A. M. Schwartzberg, J. Bokor, E. Yablonovitch, and M. C. Wu, “Radiation engineering of optical antennas for maximum field enhancement,” Nano Lett.11, 2606–2610 (2011). [CrossRef] [PubMed]
  38. Y. Chu, D. Wang, W. Zhu, and K. B. Crozier, “Double resonance surface enhanced Raman scattering substrates: an intuitive coupled oscillator model,” Opt. Express19, 14919–14928 (2011). [CrossRef] [PubMed]
  39. D. Wang, W. Zhu, Y. Chu, and K. B. Crozier, “High directivity optical antenna substrates for surface enhanced Raman scattering,” Adv. Mater.24, 4376–4380 (2012). [CrossRef] [PubMed]
  40. A. Ahmed and R. Gordon, “Single molecule directivity enhanced Raman scattering using nanoantennas,” Nano Lett.12, 2625–2630 (2012). [CrossRef] [PubMed]
  41. Yiyang Gong, Selçuk Yerci, Rui Li, Luca Dal Negro, and Jelena Vuckovic, Enhanced light emission from erbium doped silicon nitride in plasmonic metal-insulator-metal structures. Opt. Express17, (23)20642–20650 (2009). [CrossRef] [PubMed]
  42. R. Bonnett, D. J. McGarvey, A. Harriman, E. J. Land, T. G. Truscott, and U.-J. Winfield, “Photophysical properties of meso-tetraphenylporphyrin and some meso-tetra(hydroxyphenyl)porphyrins,” Photochem. Photobiol.48, 271–276 (1988). [CrossRef] [PubMed]
  43. M. Rahmani, D. Y. Lei, V. Giannini, B. Lukiyanchuk, M. Ranjbar, T. Y. F. Liew, M. Hong, and S. A. Maier, “Subgroup decomposition of plasmonic resonances in hybrid oligomers: Modeling the resonance lineshape,” Nano Lett.12, 2101–2106 (2012). [CrossRef] [PubMed]
  44. V. Giannini, A. I. Fernández-Domínguez, S. C. Heck, and S. a. Maier, “Plasmonic nanoantennas: fundamentals and their use in controlling the radiative properties of nanoemitters,” Chem. Rev.111, 3888–3912 (2011). [CrossRef] [PubMed]
  45. D. Y. Lei, A. I. Fernndez-Domnguez, Y. Sonnefraud, K. Appavoo, R. F. Haglund, J. B. Pendry, and S. A. Maier, “Revealing plasmonic gap modes in particle-on-film systems using dark-field spectroscopy,” ACS. Nano.6, 1380–1386 (2012). [CrossRef] [PubMed]
  46. P. B. Johnson and R. W. Christy, “Optical constants of the noble metals,” Phys. Rev. Lett. B6, 4370–4379 (1972).
  47. E. Prodan, C. Radloff, N. Halas, and P. Nordlander, “A hybridization model for the plasmon response of complex nanostructures,” Science302, 419–422 (2003). [CrossRef] [PubMed]
  48. A. Kinkhabwala, Z. Yu, S. Fan, Y. Avlasevich, K. Müllen, and W. E. Moerner, “Large single-molecule fluorescence enhancements produced by a bowtie nanoantenna,” Nat. Photonics3, 654–657 (2009). [CrossRef]

Cited By

Alert me when this paper is cited

OSA is able to provide readers links to articles that cite this paper by participating in CrossRef's Cited-By Linking service. CrossRef includes content from more than 3000 publishers and societies. In addition to listing OSA journal articles that cite this paper, citing articles from other participating publishers will also be listed.


« Previous Article  |  Next Article »

OSA is a member of CrossRef.

CrossCheck Deposited