Understanding localized surface plasmon resonance with propagative surface plasmon polaritons in optical nanogap antennas

Abstract

The plasmonic nanogap antenna is an efficient radiating or receiving optical device. The resonance behavior of optical antennas is commonly attributed to the excitation of a localized surface plasmon resonance (LSPR), which can be theoretically defined as the quasi-normal mode (QNM). To clarify the physical origin of the LSPR, we build up an analytical model of the LSPR by considering a multiple scattering process of propagative surface plasmon polaritons (SPPs) on the antenna arms. The model can comprehensively reproduce the complex eigenfrequency and the field distribution of QNMs of the antenna, unveiling that the LSPR arises from a Fabry-Perot resonance of SPPs. By further applying the complex pole expansion theorem of meromorphic functions, the field of the antenna under illumination by a nearby dipole emitter can be analytically expanded with QNMs, which well predicts the frequency response of the enhancement factor of radiation. The present model establishes explicit relations between the concepts of the LSPR and the propagative SPP and integrates the advantages of the Fabry-Perot and QNM formalisms of nanogap antennas.

Spatial evolution of the near-field distribution on planar gold nanoparticles with the excitation wavelength across dipole and quadrupole modes

“…Along with the development of nanotechnology, nanophotonics and plasmonics have drawn much attention over the last few decades. In particular, localized surface plasmon resonance (LSPR) has been extensively investigated because of the wide range of applications [1][2][3][4], including in sensors [5,6], photocurrent conversion [7][8][9][10][11], and artificial photosynthesis [12][13][14]. Recently, many experiments have been reported to provide direct visualization of LSPR using several approaches, such as scanning near-field optical microscopy [15][16][17], cathodoluminescence microscopy [18,19], electron energy-loss spectroscopy [19][20][21][22][23], and photoemission electron microscopy (PEEM) [24][25][26][27][28][29][30][31].…”

Flexible, stretchable, and single-molecule-sensitive SERS-active sensor for wearable biosensing applications

“…When the nanogap is very small, the surface plasmon is confined to a small volume, leading to an extremely high maximum enhancement factor. 55 However, the spread of the hotspot shown in Fig. 7(b) decreases as the nanogap size decreases, which results in a deviation of the average enhancement from the maximum enhancement trend.…”

Experimentalstudy of metasurface-based nanoantennas array fabricated using heavy ion tracking for biochemistry sensing

“…The tiny hot spots of 52 nm and 48 nm in diameter at apex of the nanoantenna for reflection and transmission are derived respectively. Two-dimensional arrays of plasmonic nanoantennas can realize a strong radiation in good directionality [13][14]. The annoantenna itself acts as a dipole which collects SPPs energy excited from surface of the sharp cone-shaped antenna and beaming.…”