Optimization of Arrays of Gold Nanodisks for Plasmon-Mediated Brillouin Light Scattering

Abstract

Distributions of electric fields in two-dimensional arrays of gold nanodisks on a Si 3 N 4 membrane, with light incident through the membrane, are modeled with the aim of determining array geometries for effective plasmon-mediated Brillouin light scattering ("surface-enhanced Brillouin scattering") from phonons or magnons in a specimen placed in contact with such an array. Particular attention is devoted to average intensities and higher-wavevector components of the fields in a plane 2 nm from the circular nanodisk/vacuum interface, which is anticipated to be in the vicinity of the surface of a specimen. For nanodisks with diameters of 50 nm, the average intensity near the circular nanodisk/vacuum interface increases as the angle of the incident light approaches the normal of the Si 3 N 4 surface. At low angles of incidence relative to the Si 3 N 4 normal, average intensities also increase with decreasing array spacing, primarily because of the corresponding changes in fractional coverage area of the gold. The highest average intensities (with near-normal incidence and 70 nm array periodicity) are found to be ∼3 times that of the incident light. More significantly, higher-wavevector components of the fields are found to have intensities comparable to the incident light. This finding provides evidence for the feasibility of using surface plasmons in nanodisk or nanoline arrays to mediate Brillouin scattering from phonons or magnons with wavelengths of a few tens of nanometers, which would extend the wavevector range of Brillouin-scattering metrology by an order of magnitude.

Plasmon-Enhanced Fluorescence Biosensors: a Review

“…For near-field interaction with the gap width between plasmonic nanoparticles >10 nm, typically only moderate enhancement occurs. For instance, | E | 2 /| E 0 | 2 ∼10 was reported for dense rectangular square arrays of gold disk nanoparticles [ 46 , 47 ] at wavelengths of 530–630 nm. Similarly, an inverse structure of densely packed nondiffractive arrays of nanoholes yields intensity enhancements of | E | 2 /| E 0 | 2 ∼16 at wavelength of λ = 600 nm [ 46 ].…”

Multifactor-Controlled Non-Monotonic Plasmon Shift of Ordered Gold Nanodisk Arrays: Shape-Dependent Interparticle Coupling

“…Recently, many studies have been focused in the optical properties of non-spherical metal nanoparticle arrays, such as nanorods [27], nanodisks [28], nanowires [29]. Yin et al reported the SPR peak shift of a one-dimensional silver cylinder array with different interparticle distances [30].…”

Mapping gigahertz vibrations in a plasmonic–phononic crystal

“…enhancement in δ R (∼120) is observed (and also in δ R/R, ∼70) compared to that of the pillar (that appears to be non-resonant at this frequency). Excluding the void-centre vibrationalresonance enhancement factor of Q ≈ 20 for this mode (see table 1), this suggests a factor ∼6 enhancement in δ R. Plasmon-mediated signal enhancements are observed in SERS [44][45][46][47][48], and related enhancements in the case of coherent acoustic phonons can be termed surfaceenhanced stimulated Brillouin scattering (SESBS) by analogy to the non-stimulated version SEBS (for which thermally-excited incoherent phonons provide the scattering source) [49,50]. By analogy with SERS or SEBS, the enhancement in SESBS depends on the plasmon-enhanced optical amplitudes at the pump and probe wavelengths.…”