Abstract
Because of their large figures of merit, surface lattice resonances (SLRs) in metal nanoparticle arrays are very promising for chemical and biomolecular sensing in both liquid and gas media. SLRs are sensitive to refractive index changes both near the surface of the nanoparticles (surface sensitivity) and in the volume between them (bulk sensitivity). Because of its intrinsic surface-sensitivity and a power law dependence on electric fields, second harmonic generation (SHG) spectroscopy can improve upon both the surface and volume sensitivities of SLRs. In this report on SHG spectroscopy of plasmonic nanoparticles, we show that the SHG signal is greatly increased (up to 450 times) by the SLRs. We also demonstrate very narrow resonances in SHG intensity (∼5 nm fwhm). We illustrate how the SHG resonances are highly sensitive to SLRs by varying the fundamental wavelength, angle of incidence, nanoparticle material, and lattice constant of the arrays. Finally, we identify an SHG resonance (10 nm fwhm) that is electric dipole forbidden and can be attributed to higher-order multipoles, enhanced by the strong near-fields of SLRs. Our results open up new and very promising avenues for chemical and biomolecular sensing based on SHG spectroscopy of SLRs.
Original language | English (US) |
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Pages (from-to) | 165-172 |
Number of pages | 8 |
Journal | Nano letters |
Volume | 19 |
Issue number | 1 |
DOIs | |
State | Published - Jan 9 2019 |
Funding
V.K.V. acknowledges support from the Royal Society through the University Research Fellowships. We acknowledge Royal Society Grant Nos. CHG\R1\170067, PEF1\170015, and RGF\EA\180228 as well as STFC ST/R005842/1. D.C.H. acknowledges funding and support from the Engineering and Physical Sciences Research Council (EPSRC) Centre for Doctoral Training in Condensed Matter Physics (CDTCMP), Grant No. EP/L015544/1. This work was also supported by the Vannevar Bush Faculty Fellowship from DOD under N00014-17-1-3023 (T.W.O.).
Keywords
- Nonlinear optics
- plasmonics
- quadrupoles
- surface lattice resonance
ASJC Scopus subject areas
- Condensed Matter Physics
- Mechanical Engineering
- Bioengineering
- General Chemistry
- General Materials Science