Influence of Fano resonance on SERS enhancement in Fano-plasmonic oligomers

Dutta, Arpan; Alam, Khairul; Nuutinen, Tarmo; Hulkko, Eero; Karvinen, Petri; Kuittinen, Markku; Toppari, J. Jussi; Vartiainen, Erik M.

doi:10.1364/oe.27.030031

Cited by 20 publications

(12 citation statements)

References 64 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…In other words, the spectral position of the highest NFIE is very close to the Fano dip in the scattering profile. Such correlation is a general property of Fano-resonant systems, reported earlier in theoretical [52] and experimental studies [45,51].…”

Section: Resultssupporting

confidence: 56%

“…Lower the value of q-parameter, higher the depth of the Fano dip, stronger the FR. The strength of FR in a Fano-plasmonic oligomer can directly influence its Raman enhancement capability [45,51]. Therefore, we optimized the geometrical parameters of the oligomers such a way that their FR spectrally overlapped with the pump, Stokes and CARS regions while maintaining the lowest q-parameter value to ensure the highest Raman enhancement.…”

Section: Resultsmentioning

confidence: 99%

See 1 more Smart Citation

Spatial localization of hotspots in Fano-resonant plasmonic oligomers for surface-enhanced coherent anti-Stokes Raman scattering

Dutta

Vartiainen

2020

J. Eur. Opt. Soc.-Rapid Publ.

Self Cite

View full text Add to dashboard Cite

Realization of Fano resonance in plasmonic oligomers is often exploited to design efficient plasmonic substrates for surface-enhanced coherent anti-Stokes Raman scattering. Disk-type Fano-resonant plasmonic oligomers are widely used to enhance the Raman signal of the probe material. Generally, hot spots are generated in those oligomers at different spatial locations at different wavelengths and only a few spatially overlapping hot spots at multiple wavelengths can be achieved with oblique incidence of excitation light. In this work, we proposed hexagonal gold nanoparticle based Fano-resonant plasmonic oligomers that can yield higher number of spatially overlapped hot spots compared to the disk type oligomers even with the normal incidence of excitation light. The oligomers were numerically modelled and optimized for surface-enhanced coherent anti-Stokes Raman scattering with 780 nm pumping and 500–1800 cm− 1 Raman signature region. The Fano lineshape was engineered to ensure near-field energy coupling at pump while enhancing the coherent anti-Stokes Raman signal at the far field. Our computational studies explored the purely electric origin of Fano resonance in those oligomers and provided maximum Raman enhancements of 1012–1013 from them to enable single-molecular level applications. Our findings provide a way to realize fabrication-friendly nanostructures with higher number of spatially localized hotspots for improving the Raman detection sensitivity.

show abstract

Section: Resultssupporting

confidence: 56%

Section: Resultsmentioning

confidence: 99%

Spatial localization of hotspots in Fano-resonant plasmonic oligomers for surface-enhanced coherent anti-Stokes Raman scattering

Dutta

Vartiainen

2020

J. Eur. Opt. Soc.-Rapid Publ.

Self Cite

View full text Add to dashboard Cite

show abstract

“…Since the electromagnetic enhancement factor of SERS is a product of NFIE at the excitation and the Stokes wavelengths, i.e. G SERS = |E loc(excitation) /E 0 | 2 × |E loc(Stokes) /E 0 | 2 [25,26], the 'bluest' reflection minimum will always provide the highest G SERS among the three reflection minima. Therefore, we optimized the spectral position of the 'bluest' reflection minimum of the gratings with different detunings from the excitation line to systematically study their effect on SERS.…”

Section: Resultsmentioning

confidence: 99%

“…Plasmonic nanostructures for SERS typically include metallic nanoantennas with regular geometries such as nanospheres, nanocubes, nanotriangles, nanorods, nanotips [21][22][23], as well as irregular-shaped nanoparticles [24] and nanoparticle oligomers [25][26][27]. Periodic structures with lattice resonances, such as plasmonic gratings [28][29][30][31][32][33][34] and nanoparticle arrays [35], are also used as SERS substrates.…”

Section: Introductionmentioning

confidence: 99%

Fabrication-friendly polarization-sensitive plasmonic grating for optimal surface-enhanced Raman spectroscopy

Dutta

Nuutinen

Alam

et al. 2020

J. Eur. Opt. Soc.-Rapid Publ.

Self Cite

View full text Add to dashboard Cite

Plasmonic nanostructures are widely utilized in surface-enhanced Raman spectroscopy (SERS) from ultraviolet to near-infrared applications. Periodic nanoplasmonic systems such as plasmonic gratings are of great interest as SERS-active substrates due to their strong polarization dependence and ease of fabrication. In this work, we modelled a silver grating that manifests a subradiant plasmonic resonance as a dip in its reflectivity with significant near-field enhancement only for transverse-magnetic (TM) polarization of light. We investigated the role of its fill factor, commonly defined as a ratio between the width of the grating groove and the grating period, on the SERS enhancement. We designed multiple gratings having different fill factors using finite-difference time-domain (FDTD) simulations to incorporate different degrees of spectral detunings in their reflection dips from our Raman excitation (488 nm). Our numerical studies suggested that by tuning the spectral position of the optical resonance of the grating, via modifying their fill factor, we could optimize the achievable SERS enhancement. Moreover, by changing the polarization of the excitation light from transverse-magnetic to transverse-electric, we can disable the optical resonance of the gratings resulting in negligible SERS performance. To verify this, we fabricated and optically characterized the modelled gratings and ensured the presence of the desired detunings in their optical responses. Our Raman analysis on riboflavin confirmed that the higher overlap between the grating resonance and the intended Raman excitation yields stronger Raman enhancement only for TM polarized light. Our findings provide insight on the development of fabrication-friendly plasmonic gratings for optimal intensification of the Raman signal with an extra degree of control through the polarization of the excitation light. This feature enables studying Raman signal of exactly the same molecules with and without electromagnetic SERS enhancements, just by changing the polarization of the excitation, and thereby permits detailed studies on the selection rules and the chemical enhancements possibly involved in SERS.

show abstract

“…Furthermore, Fano resonance is drawing intense interest due to its high sensitivity to geometric parameters and the refractive index changes [7,[9][10][11][12][13]. Therefore, Fano resonance can be used in many applications, such as surface-enhanced Raman spectroscopy, surface-enhanced fluorescence, surface plasmon photon chips, resonators, nano-antennas, couplers, biosensors, and optical filtering [14][15][16][17][18][19][20][21][22][23].…”

Section: Introductionmentioning

confidence: 99%

Tunable Magnetic Fano Resonances on Au Nanosphere Dimer–Dielectric–Gold Film Sandwiched Structure

et al. 2021

View full text Add to dashboard Cite

The Fano resonance demonstrates excellent performance due to its narrow asymmetrical spectral line shape, and its sensitivity to structure and material parameter changes. Compared to conventional Fano resonances, the Fano resonance generated by the magnetic dipole is more advantageous because of its high absorption and low loss. In this study, we propose an Au nanosphere dimer–dielectric–gold film sandwiched structure that supports the magnetic Fano resonance mode. And the Fano resonance can be efficiently tuned from visible to near-infrared wavelength by changing the size of the gold nanospheres and the thickness of the dielectric layer. Different from the single gold nanosphere–dielectric–film structure, the results suggest that the proposed structure is sensitive to the polarization direction of the excitation light. Considering the above characteristics, the proposed structure can be applied in multi-band sensing, surface-enhanced Raman spectroscopy, and dynamically adjustable optical switches.

show abstract

Influence of Fano resonance on SERS enhancement in Fano-plasmonic oligomers

Cited by 20 publications

References 64 publications

Spatial localization of hotspots in Fano-resonant plasmonic oligomers for surface-enhanced coherent anti-Stokes Raman scattering

Spatial localization of hotspots in Fano-resonant plasmonic oligomers for surface-enhanced coherent anti-Stokes Raman scattering

Fabrication-friendly polarization-sensitive plasmonic grating for optimal surface-enhanced Raman spectroscopy

Tunable Magnetic Fano Resonances on Au Nanosphere Dimer–Dielectric–Gold Film Sandwiched Structure

Contact Info

Product

Resources

About