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Whispering-gallery nanocavity plasmon-enhanced Raman spectroscopy.

Zhang J, Li J, Tang S, Fang Y, Wang J, Huang G, Liu R, Zheng L, Cui X, Mei Y - Sci Rep (2015)

Bottom Line: The synergy effect in nature could enable fantastic improvement of functional properties and associated effects.The detection performance of surface-enhanced Raman scattering (SERS) can be highly strengthened under the cooperation with other factors.Such synchronous and coherent coupling between plasmonics and photonics could lead to new principle and design for various sub-wavelength optical devices, e.g. plasmonic waveguides and hyperbolic metamaterials.

View Article: PubMed Central - PubMed

Affiliation: Department of Materials Science, Fudan University, Shanghai 200433, People's Republic of China.

ABSTRACT
The synergy effect in nature could enable fantastic improvement of functional properties and associated effects. The detection performance of surface-enhanced Raman scattering (SERS) can be highly strengthened under the cooperation with other factors. Here, greatly-enhanced SERS detection is realized based on rolled-up tubular nano-resonators decorated with silver nanoparticles. The synergy effect between whispering-gallery-mode (WGM) and surface plasmon leads to an extra enhancement at the order of 10(5) compared to non-resonant flat SERS substrates, which can be well tuned by altering the diameter of micron- and nanotubes and the excitation laser wavelengths. Such synchronous and coherent coupling between plasmonics and photonics could lead to new principle and design for various sub-wavelength optical devices, e.g. plasmonic waveguides and hyperbolic metamaterials.

No MeSH data available.


Related in: MedlinePlus

Tunability of WGMs and Raman enhancement in the plasmon nanocavity.(a) Relative Raman enhancement of the R6G as a function of plasmon nanocavity diameter using a 514.5-nm excitation. The calculated /E/4 (red line) in the cavity wall is plotted together with the measured Raman intensity (blue circles). (b) Electric field distribution at 514.5 nm in the plasmon nanocavity with various diameters calculated by FDTD simulation. (c,d) Calculated field profiles for the resonant cases in plasmon nanocavities with a 514.5-nm excitation, showing the whispering-gallery plasmon cavity modes for the cavity diameter of 500 nm (azimuthal mode number, m = 3) (c) and 820 nm (m = 5), (d) respectively. (e) Relative Raman enhancement of the R6G as a function of plasmon nanocavity diameter using a 632.8-nm excitation. The calculated /E/4 in the cavity wall is plotted together with the Raman intensity. (f) Electric field distribution at 632.8 nm wavelength of WGMs in the plasmon nanocavity with various diameters calculated by FDTD simulation. (g,h) SEM image (g) and optical microscopy image (h) of a conical plasmon nanocavity with diameters varying from 150 to 900 nm. (i) Raman intensity mapping of the R6G signal at 1364 cm−1 from a conical plasmon nanocavity; R6G concentration is 10−5 M; excitation wavelength is 514.5 nm. (j) Superposition of images h and i. Scale bar is 1 μm.
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f3: Tunability of WGMs and Raman enhancement in the plasmon nanocavity.(a) Relative Raman enhancement of the R6G as a function of plasmon nanocavity diameter using a 514.5-nm excitation. The calculated /E/4 (red line) in the cavity wall is plotted together with the measured Raman intensity (blue circles). (b) Electric field distribution at 514.5 nm in the plasmon nanocavity with various diameters calculated by FDTD simulation. (c,d) Calculated field profiles for the resonant cases in plasmon nanocavities with a 514.5-nm excitation, showing the whispering-gallery plasmon cavity modes for the cavity diameter of 500 nm (azimuthal mode number, m = 3) (c) and 820 nm (m = 5), (d) respectively. (e) Relative Raman enhancement of the R6G as a function of plasmon nanocavity diameter using a 632.8-nm excitation. The calculated /E/4 in the cavity wall is plotted together with the Raman intensity. (f) Electric field distribution at 632.8 nm wavelength of WGMs in the plasmon nanocavity with various diameters calculated by FDTD simulation. (g,h) SEM image (g) and optical microscopy image (h) of a conical plasmon nanocavity with diameters varying from 150 to 900 nm. (i) Raman intensity mapping of the R6G signal at 1364 cm−1 from a conical plasmon nanocavity; R6G concentration is 10−5 M; excitation wavelength is 514.5 nm. (j) Superposition of images h and i. Scale bar is 1 μm.

Mentions: For the purpose of demonstrating the tunability of WGMs as well as the Raman enhancement factor of the nanodevice, a series of Raman measurements was performed on a conical plasmon nanocavity with diameters ranging from 242 to 1030 nm (Fig. 3a, right vertical axis) along a conical tube. The theoretical result based on Mie-scattering as a function of tube diameter is also presented by the red line in Fig. 3a, while the left vertical axis stands for the averaged quadruplicate electric field intensity in the tube wall. Figure 3b shows the finite-difference time-domain (FDTD) simulation of /E/2 distribution in the tubular plasmon nanocavity at the excitation wavelength of 514.5 nm. The size-dependent enhancements in Fig. 3a,b do not show a monotonic increase with increasing size of the nanocavities, but show a series of peaks at diameters of ~500 and 820 nm. The normalized Raman signal peak intensity at 1364 cm−1 of R6G measured from the conical plasmonic nanocavity (blue circles) agrees well with the theoretical estimations, while much stronger Raman signals were obtained at the positions with diameters of 490 and 850 nm (Fig. 3a). FDTD simulations from Fig. 3c demonstrate that the enhancement at the tube diameter of ~500 nm mainly originates from the resonant mode with azimuthal number m = 3, while the enhancement at the tube diameter of ~820 nm mainly results from the resonant mode with azimuthal number m = 5.


Whispering-gallery nanocavity plasmon-enhanced Raman spectroscopy.

Zhang J, Li J, Tang S, Fang Y, Wang J, Huang G, Liu R, Zheng L, Cui X, Mei Y - Sci Rep (2015)

Tunability of WGMs and Raman enhancement in the plasmon nanocavity.(a) Relative Raman enhancement of the R6G as a function of plasmon nanocavity diameter using a 514.5-nm excitation. The calculated /E/4 (red line) in the cavity wall is plotted together with the measured Raman intensity (blue circles). (b) Electric field distribution at 514.5 nm in the plasmon nanocavity with various diameters calculated by FDTD simulation. (c,d) Calculated field profiles for the resonant cases in plasmon nanocavities with a 514.5-nm excitation, showing the whispering-gallery plasmon cavity modes for the cavity diameter of 500 nm (azimuthal mode number, m = 3) (c) and 820 nm (m = 5), (d) respectively. (e) Relative Raman enhancement of the R6G as a function of plasmon nanocavity diameter using a 632.8-nm excitation. The calculated /E/4 in the cavity wall is plotted together with the Raman intensity. (f) Electric field distribution at 632.8 nm wavelength of WGMs in the plasmon nanocavity with various diameters calculated by FDTD simulation. (g,h) SEM image (g) and optical microscopy image (h) of a conical plasmon nanocavity with diameters varying from 150 to 900 nm. (i) Raman intensity mapping of the R6G signal at 1364 cm−1 from a conical plasmon nanocavity; R6G concentration is 10−5 M; excitation wavelength is 514.5 nm. (j) Superposition of images h and i. Scale bar is 1 μm.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4595732&req=5

f3: Tunability of WGMs and Raman enhancement in the plasmon nanocavity.(a) Relative Raman enhancement of the R6G as a function of plasmon nanocavity diameter using a 514.5-nm excitation. The calculated /E/4 (red line) in the cavity wall is plotted together with the measured Raman intensity (blue circles). (b) Electric field distribution at 514.5 nm in the plasmon nanocavity with various diameters calculated by FDTD simulation. (c,d) Calculated field profiles for the resonant cases in plasmon nanocavities with a 514.5-nm excitation, showing the whispering-gallery plasmon cavity modes for the cavity diameter of 500 nm (azimuthal mode number, m = 3) (c) and 820 nm (m = 5), (d) respectively. (e) Relative Raman enhancement of the R6G as a function of plasmon nanocavity diameter using a 632.8-nm excitation. The calculated /E/4 in the cavity wall is plotted together with the Raman intensity. (f) Electric field distribution at 632.8 nm wavelength of WGMs in the plasmon nanocavity with various diameters calculated by FDTD simulation. (g,h) SEM image (g) and optical microscopy image (h) of a conical plasmon nanocavity with diameters varying from 150 to 900 nm. (i) Raman intensity mapping of the R6G signal at 1364 cm−1 from a conical plasmon nanocavity; R6G concentration is 10−5 M; excitation wavelength is 514.5 nm. (j) Superposition of images h and i. Scale bar is 1 μm.
Mentions: For the purpose of demonstrating the tunability of WGMs as well as the Raman enhancement factor of the nanodevice, a series of Raman measurements was performed on a conical plasmon nanocavity with diameters ranging from 242 to 1030 nm (Fig. 3a, right vertical axis) along a conical tube. The theoretical result based on Mie-scattering as a function of tube diameter is also presented by the red line in Fig. 3a, while the left vertical axis stands for the averaged quadruplicate electric field intensity in the tube wall. Figure 3b shows the finite-difference time-domain (FDTD) simulation of /E/2 distribution in the tubular plasmon nanocavity at the excitation wavelength of 514.5 nm. The size-dependent enhancements in Fig. 3a,b do not show a monotonic increase with increasing size of the nanocavities, but show a series of peaks at diameters of ~500 and 820 nm. The normalized Raman signal peak intensity at 1364 cm−1 of R6G measured from the conical plasmonic nanocavity (blue circles) agrees well with the theoretical estimations, while much stronger Raman signals were obtained at the positions with diameters of 490 and 850 nm (Fig. 3a). FDTD simulations from Fig. 3c demonstrate that the enhancement at the tube diameter of ~500 nm mainly originates from the resonant mode with azimuthal number m = 3, while the enhancement at the tube diameter of ~820 nm mainly results from the resonant mode with azimuthal number m = 5.

Bottom Line: The synergy effect in nature could enable fantastic improvement of functional properties and associated effects.The detection performance of surface-enhanced Raman scattering (SERS) can be highly strengthened under the cooperation with other factors.Such synchronous and coherent coupling between plasmonics and photonics could lead to new principle and design for various sub-wavelength optical devices, e.g. plasmonic waveguides and hyperbolic metamaterials.

View Article: PubMed Central - PubMed

Affiliation: Department of Materials Science, Fudan University, Shanghai 200433, People's Republic of China.

ABSTRACT
The synergy effect in nature could enable fantastic improvement of functional properties and associated effects. The detection performance of surface-enhanced Raman scattering (SERS) can be highly strengthened under the cooperation with other factors. Here, greatly-enhanced SERS detection is realized based on rolled-up tubular nano-resonators decorated with silver nanoparticles. The synergy effect between whispering-gallery-mode (WGM) and surface plasmon leads to an extra enhancement at the order of 10(5) compared to non-resonant flat SERS substrates, which can be well tuned by altering the diameter of micron- and nanotubes and the excitation laser wavelengths. Such synchronous and coherent coupling between plasmonics and photonics could lead to new principle and design for various sub-wavelength optical devices, e.g. plasmonic waveguides and hyperbolic metamaterials.

No MeSH data available.


Related in: MedlinePlus