Resonance modes, cavity field enhancements, and long-range collective photonic effects in periodic bowtie nanostructures

Abstract

The discovery of single-molecule sensitivity via surface-enhanced Raman scattering on resonantly excited noble metal nanoparticles has brought an increasing interest in its applications to the molecule detection and identification. Periodic gold bowtie nanostructures have recently been shown to give a large enhancement factor sufficient for single molecule detection. In this work, we simulate the plasmon resonance for periodic gold bowtie nanostructures. The difference between the dipole and the quadrupole resonances is described by examining the magnitude and phase of electric field, the bound surface charge, and the polarization. The gap size dependence of the field enhancement can be interpreted by considering cavity field enhancement. Also, additional enhancement is obtained through the long-range collective photonic effect when the bowtie array periodicity matches the resonance wavelength.

Anti-reflection textured structures by wet etching and island lithography for surface-enhanced Raman spectroscopy

“…6. The maximum scattering of metallic nanostructures is dominated by the collective LSPR due to the oscillations of the free electrons [46] which corresponds to the minimum reflectance [22]. It can be seen that the resonance wavelengths in the measured scattering spectra are located at 643, 720, and 692 nm, respectively, for nanopillar, pyramid, nanopillar-on-pyramid structures which correspond to the longitudinal LSPR in the simulated reflectance spectra shown in Fig.…”

“…The optical properties of periodic nanostructures, such as bowtie [15,[20][21][22], contour bowtie [23], nanotube [24] and disk nanoantennas [25] on SERS, have been discussed. However, the slow processing efficiency and high-cost are the main limitations of mass production by using these techniques.…”

Optimized Sensitivity and Electric Field Enhancement by Controlling Localized Surface Plasmon Resonances for Bowtie Nanoring Nanoantenna Arrays

“…With the help of nanofabrication techniques, such as electron-beam lithography, it has been shown that a large electromagnetic field can be excited and confined in the gap of a bowtie-shaped nanoantenna, where two metallic triangular prisms face tip-to-tip and are separated by a small gap [14][15][16][17][18]. In addition, several methods have been used to increase the sensitivity of the nanoplasmonic structure [19][20][21], and a large number of investigations of nanoring structures, similar to core-shell nanoparticles in the solution, have exhibited better electric field enhancement and sensitivity while varying the local dielectric media compared to solid nanodisk structures [22,23].…”

Free-standing gold elliptical nanoantenna with tunable wavelength in near-infrared region for enhanced Raman spectroscopy

“…Localized surface plasmon has been widely used on surface-enhanced Raman spectroscopy (SERS) [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16]. Coupling between two metal surfaces separated by few nanometers brings localized surface plasmon to resonate at the gap and induces large electromagnetic field enhancement.…”

“…The resonance wavelength is strongly dependent on the geometry of the antenna, and the enhancement factor can be manipulated by the gap distance [1] or the corner radius [17]. Recently, the enhancement factor has shown the dependence on the column and row distances of the periodic nanostructure due to the long-range resonance between each individual bowtie antenna [2][3][4][5]. The maximum enhancement can be achieved as the periodic distance in the polarization direction matches the incident wavelength for the bowtie structure [6].…”