Near-field excitation of nanoantenna resonance

Abstract

An array of paired elliptic nanoparticles designed to enhance local fields around the particle pair is fabricated with gold embedded in quartz. Light excites a coupled plasmon resonance in the particle pair and the system acts like a plasmonic nanoantenna providing an enhanced electromagnetic field. Near-field scanning optical microscopy and finite element modeling are used to study the local field effects of the nanoantenna system. Local illumination shows similar resonant properties as plane wave illumination: a strong, localized optical resonance for light polarized parallel to the main, center-to-center axis.

Enhanced localized fluorescence in plasmonic nanoantennae

“…For the orthogonal polarization, coupled particles exhibit a weaker resonance at shorter wavelengths ͑in the green͒ due to their minor axis length ͑Y direction͒. 29 The fluorescence spectrum of Rh800 overlaps with the LSPR of the two presented antenna geometries; see Fig. 2.…”

“…1 and are similar in design to those reported in Ref. 29. The pattern is written in a resist ͑ZEP520A͒ on a quartz substrate using electron beam lithography ͑JEOL JBX-9300FS͒.…”

“…[19][20][21] The nanoantenna ͑also known as an optical antenna͒ system consisting of single or coupled nanoparticles, either isolated or arrayed, is well studied. [5][6][7][8][9][10][11][12][13][14][15][22][23][24][25][26][27][28][29] The system of two closely spaced nanoparticles is of particular interest as the LSPR of individual particles couple, resulting in greater electric field enhancement [24][25][26] and a systematic red shift compared to a single particle. [22][23][24]28 Field enhancements afforded by LSPRs result in enhanced emission of dyes and QDs in the vicinity of the nanoparticles.…”

“…These features do not represent resonant scattering from a LSPR, as the contrast ratio between I max and I min is very low compared with NSOM imaging on a nanoantenna sample at a resonant wavelength. 29 A linear polarizer placed in the collection path is used to observe the polarization state of the enhanced fluorescence and is characterized to be mainly parallel to the major antenna axis. With x-polarized light ͓Fig.…”

Novel optical antenna designs of comb shaped split ring architecture for NIR and MIR enhanced field localization

“…Different from the plasmonic structures of waveguides and transmission apertures, optical antennas generate hot spots at very high intensities in a region beyond the diffraction limit [2]. Therefore, optical antennas are useful for a number of important applications including ultra-sensitive optical detectors.To this end, different types of optical antennas have been widely investigated to date [3][4][5][6]. However, in these nanoantennas, if using a simple architecture, the field enhancements are not at a maximum feasible level, or they have complicated 3D architectures and/or very sharp tips, which are technically challenging to fabricate.…”