scholarly journals Modifying Plasmonic-Field Enhancement and Resonance Characteristics of Spherical Nanoparticles on Metallic Film: Effects of Faceting Spherical Nanoparticle Morphology

Coatings ◽  
2019 ◽  
Vol 9 (6) ◽  
pp. 387 ◽  
Author(s):  
Vasanthan Devaraj ◽  
Hyuk Jeong ◽  
Chuntae Kim ◽  
Jong-Min Lee ◽  
Jin-Woo Oh
Keyword(s):  
Near Infrared ◽  
Near Field ◽  
Three Dimensional ◽  
Field Enhancement ◽  
Device Fabrication ◽  
Metallic Film ◽  
Linear Optics ◽  
Cross Sectional ◽  
Non Linear Optics ◽  
Surface Enhanced

A three-dimensional finite-difference time-domain study of the plasmonic structure of nanoparticles on metallic film (NPOM) is presented in this work. An introduction to nanoparticle (NP) faceting in the NPOM structure produced a variety of complex transverse cavity modes, which were labeled S11 to S13. We observed that the dominant S11 mode resonance could be tuned to the desired wavelength within a broadband range of ~800 nm, with a maximum resonance up to ~1.42 µm, as a function of NP facet width. Despite being tuned at the broad spectral range, the S11 mode demonstrated minimal decrease in its near field enhancement characteristics, which can be advantageous for surface-enhanced spectroscopy applications and device fabrication perspectives. The identification of mode order was interpreted using cross-sectional electric field profiles and three-dimensional surface charge mapping. We realized larger local field enhancement in the order of ~109, even for smaller NP diameters of 50 nm, as function of the NP faceting effect. The number of radial modes were dependent upon the combination of NP diameter and faceting length. We hope that, by exploring the sub-wavelength complex optical properties of the plasmonic structures of NPOM, a variety of exciting applications will be revealed in the fields of sensors, non-linear optics, device engineering/processing, broadband tunable plasmonic devices, near-infrared plasmonics, and surface-enhanced spectroscopy.

scholarly journals Dumbbell gold nanoparticle dimer antennas with advanced optical properties

2018 ◽  
Vol 9 ◽  
pp. 2188-2197 ◽  
Author(s):  
Janning F Herrmann ◽  
Christiane Höppener
Keyword(s):  
Gold Nanoparticle ◽  
Single Molecule ◽  
Near Field ◽  
Field Enhancement ◽  
Building Blocks ◽  
Far Field ◽  
Linear Optics ◽  
Non Linear Optics ◽  
Fundamental Limitations ◽  
Plasmonic Nanoantennas

Plasmonic nanoantennas have found broad applications in the fields of photovoltaics, electroluminescence, non-linear optics and for plasmon enhanced spectroscopy and microscopy. Of particular interest are fundamental limitations beyond the dipolar approximation limit. We introduce asymmetric gold nanoparticle antennas (AuNPs) with improved optical near-field properties based on the formation of sub-nanometer size gaps, which are suitable for studying matter with high-resolution and single molecule sensitivity. These dumbbell antennas are characterized in regard to their far-field and near-field properties and are compared to similar dimer and trimer antennas with larger gap sizes. The tailoring of the gap size down to sub-nanometer length scales is based on the integration of rigid macrocyclic cucurbituril molecules. Stable dimer antennas are formed with an improved ratio of the electromagnetic field enhancement and confinement. This ratio, taken as a measure of the performance of an antenna, can even exceed that exhibited by trimer AuNP antennas composed of comparable building blocks with larger gap sizes. Fluctuations in the far-field and near-field properties are observed, which are likely caused by distinct deviations of the gap geometry arising from the faceted structure of the applied colloidal AuNPs.

scholarly journals Plasmonic interference modulation for broadband nanofocusing

Nanophotonics ◽  
2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Shaobo Li ◽  
Shuming Yang ◽  
Fei Wang ◽  
Qiang Liu ◽  
Biyao Cheng ◽  
...  
Keyword(s):  
Near Field ◽  
Three Dimensional ◽  
Field Enhancement ◽  
Incident Beam ◽  
Plasmonic Mode ◽  
Resonant Structures ◽  
Interference Modulation ◽  
Near Field Imaging ◽  
Linearly Polarized ◽  
Radially Polarized

Abstract Metallic plasmonic probes have been successfully applied in near-field imaging, nanolithography, and Raman enhanced spectroscopy because of their ability to squeeze light into nanoscale and provide significant electric field enhancement. Most of these probes rely on nanometric alignment of incident beam and resonant structures with limited spectral bandwidth. This paper proposes and experimentally demonstrates an asymmetric fiber tip for broadband interference nanofocusing within its full optical wavelengths (500–800 nm) at the nanotip with 10 nm apex. The asymmetric geometry consisting of two semicircular slits rotates plasmonic polarization and converts the linearly polarized plasmonic mode to the radially polarized plasmonic mode when the linearly polarized beam couples to the optical fiber. The three-dimensional plasmonic modulation induces circumference interference and nanofocus of surface plasmons, which is significantly different from the nanofocusing through plasmon propagation and plasmon evolution. The plasmonic interference modulation provides fundamental insights into the plasmon engineering and has important applications in plasmon nanophotonic technologies.

scholarly journals Metal–dielectric hybrid nanoantennas for efficient frequency conversion at the anapole mode

2018 ◽  
Vol 9 ◽  
pp. 2306-2314 ◽  
Author(s):  
Valerio F Gili ◽  
Lavinia Ghirardini ◽  
Davide Rocco ◽  
Giuseppe Marino ◽  
Ivan Favero ◽  
...  
Keyword(s):  
Frequency Conversion ◽  
Near Infrared ◽  
Strong Field ◽  
Second Harmonic ◽  
Near Field ◽  
Field Enhancement ◽  
High Refractive Index ◽  
Plasmonic Nanostructures ◽  
Ohmic Losses ◽  
Order Of Magnitude

Background: Dielectric nanoantennas have recently emerged as an alternative solution to plasmonics for nonlinear light manipulation at the nanoscale, thanks to the magnetic and electric resonances, the strong nonlinearities, and the low ohmic losses characterizing high refractive-index materials in the visible/near-infrared (NIR) region of the spectrum. In this frame, AlGaAs nanoantennas demonstrated to be extremely efficient sources of second harmonic radiation. In particular, the nonlinear polarization of an optical system pumped at the anapole mode can be potentially boosted, due to both the strong dip in the scattering spectrum and the near-field enhancement, which are characteristic of this mode. Plasmonic nanostructures, on the other hand, remain the most promising solution to achieve strong local field confinement, especially in the NIR, where metals such as gold display relatively low losses. Results: We present a nonlinear hybrid antenna based on an AlGaAs nanopillar surrounded by a gold ring, which merges in a single platform the strong field confinement typically produced by plasmonic antennas with the high nonlinearity and low loss characteristics of dielectric nanoantennas. This platform allows enhancing the coupling of light to the nanopillar at coincidence with the anapole mode, hence boosting both second- and third-harmonic generation conversion efficiencies. More than one order of magnitude enhancement factors are measured for both processes with respect to the isolated structure. Conclusion: The present results reveal the possibility to achieve tuneable metamixers and higher resolution in nonlinear sensing and spectroscopy, by means of improved both pump coupling and emission efficiency due to the excitation of the anapole mode enhanced by the plasmonic nanoantenna.

scholarly journals Towards rational design and optimization of near-field enhancement and spectral tunability of hybrid core-shell plasmonic nanoprobes

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Debadrita Paria ◽  
Chi Zhang ◽  
Ishan Barman
Keyword(s):  
Single Molecule ◽  
Rational Design ◽  
Near Infrared ◽  
Theoretical Calculations ◽  
Near Field ◽  
Field Enhancement ◽  
Infrared Region ◽  
Core Shell ◽  
Optimization Strategy ◽  
Design And Optimization

Abstract In biology, sensing is a major driver of discovery. A principal challenge is to create a palette of probes that offer near single-molecule sensitivity and simultaneously enable multiplexed sensing and imaging in the “tissue-transparent” near-infrared region. Surface-enhanced Raman scattering and metal-enhanced fluorescence have shown substantial promise in addressing this need. Here, we theorize a rational design and optimization strategy to generate nanostructured probes that combine distinct plasmonic materials sandwiching a dielectric layer in a multilayer core shell configuration. The lower energy resonance peak in this multi-resonant construct is found to be highly tunable from visible to the near-IR region. Such a configuration also allows substantially higher near-field enhancement, compared to a classical core-shell nanoparticle that possesses a single metallic shell, by exploiting the differential coupling between the two core-shell interfaces. Combining such structures in a dimer configuration, which remains largely unexplored at this time, offers significant opportunities not only for near-field enhancement but also for multiplexed sensing via the (otherwise unavailable) higher order resonance modes. Together, these theoretical calculations open the door for employing such hybrid multi-layered structures, which combine facile spectral tunability with ultrahigh sensitivity, for biomolecular sensing.

Effect of Substrate and Nanoparticle Spacing on Plasmonic Enhancement in Three-Dimensional Nanoparticle Structures

2017 ◽  
Vol 5 (4) ◽  
Author(s):  
Anil Yuksel ◽  
Edward T. Yu ◽  
Jayathi Murthy ◽  
Michael Cullinan
Keyword(s):  
Near Field ◽  
Three Dimensional ◽  
Polarized Light ◽  
Field Enhancement ◽  
Transverse Magnetic ◽  
Plasmonic Enhancement ◽  
Nanoparticle Assemblies ◽  
Nanoparticle Interactions ◽  
Gap Spacing ◽  
532 Nm

Surface plasmon polaritons associated with light-nanoparticle interactions can result in dramatic enhancement of electromagnetic fields near and in the gaps between the particles, which can have a large effect on the sintering of these nanoparticles. For example, the plasmonic field enhancement within nanoparticle assemblies is affected by the particle size, spacing, interlayer distance, and light source properties. Computational analysis of plasmonic effects in three-dimensional (3D) nanoparticle packings are presented herein using 532 nm plane wave light. This analysis provides insight into the particle interactions both within and between adjacent layers for multilayer nanoparticle packings. Electric field enhancements up to 400-fold for transverse magnetic (TM) or X-polarized light and 26-fold for transverse electric (TE) or Y-polarized light are observed. It is observed that the thermo-optical properties of the nanoparticle packings change nonlinearly between 0 and 10 nm gap spacing due to the strong and nonlocal near-field interaction between the particles for TM polarized light, but this relationship is linear for TE polarized light. These studies help provide a foundation for understanding micro/nanoscale heating and heat transport for Cu nanoparticle packings under 532 nm light under different polarization for the photonic sintering of nanoparticle assemblies.

Optoelectronic and Electronic Properties of Tetracyanoindane for Chemical Doping of Organic Semiconductors

MRS Advances ◽  
2019 ◽  
Vol 4 (31-32) ◽  
pp. 1811-1819
Author(s):  
Jenna Crawford ◽  
Harold O. Lee ◽  
Sam-Shajing Sun
Keyword(s):  
Organic Semiconductors ◽  
Near Infrared ◽  
Chemical Doping ◽  
Linear Optics ◽  
Large Area ◽  
Strong Electron ◽  
Non Linear Optics ◽  
Current Voltage ◽  
Common Technique ◽  
Cyano Groups

ABSTRACTChemical doping of organic semiconductors is a common technique used to increase the performance numerous organic electronic and optoelectronic devices. Tetrafluoro-tetracyanoquinodimethane (F4-TCNQ) is one of the most widely known p-dopants having the properties necessary to act as a strong electron acceptor. Despite its strong electron accepting abilities, F4-TCNQ is extremely expensive, making it less than ideal for large-area applications. Here, we introduce a small molecule called Tetracyanoindane (TCI) as a potential p-dopant. Widely known for its role in the field of non-linear optics, its high polarizability arises from the addition of four cyano-groups, which are electron withdrawing groups. The four cyano-groups are also seen in the F4-TCNQ molecule and contributes to the withdrawing strength alongside the four fluorine atoms present. We hypothesize that TCI could have similar accepting strength to F4-TCNQ and could potentially replace it as a cheaper alternative. In this study, Cyclic Voltammetry (CV), UV-Visible-Near Infrared Spectroscopy (UV/Vis/NIR), Photoluminescence (PL), Current-Voltage (IV) measurements analysis was conducted to compare the accepting strength of TCI and F4-TCNQ. Then, the two molecules were added to Poly-3-hexy-thiophene (P3HT) to observe how readily they dope the organic semiconductor.

Simulation of Electromagnetic Field Distribution at a Nanowire Probe for Near Field Scanning Optical Microscopy

2008 ◽  
Author(s):  
Nathan P. Malcolm ◽  
Alex J. Heltzel ◽  
Li Shi ◽  
John R. Howell
Keyword(s):  
Optical Microscopy ◽  
Signal To Noise Ratio ◽  
Near Field ◽  
Three Dimensional ◽  
Field Enhancement ◽  
Fdtd Simulation ◽  
Plasmonic Nanoparticle ◽  
Excitation Laser ◽  
Scanning Optical Microscopy ◽  
Near Field Scanning

This work studies a new design of a near field scanning optical microscopy (NSOM) probe based on a ZnO nanowire sub-wavelength waveguide terminated with a plasmonic gold nanoparticle. Three-dimensional finite difference time domain (FDTD) simulation is used to visualize light guiding in the nanowire and near field coupling between the plasmonic nanoparticle and the substrate. The simulation results reveal local field enhancement at the gap between the nanoparticle and a gold substrate when the nanowire axis is tilted from the substrate normal by a small angle. The enhancement occurs only along the cross section plane that is parallel to the polarization of the excitation laser beam. The regime of field enhancement is much smaller than the diameter of the 100 nm plasmonic particle, making the nanowire probe well suited for NSOM with superior spatial resolution and signal to noise ratio compared to the state of the art.

scholarly journals Plasmons driven by single electrons in graphene nanoislands

Nanophotonics ◽  
2013 ◽  
Vol 2 (2) ◽  
pp. 139-151 ◽  
Author(s):  
Alejandro Manjavacas ◽  
Sukosin Thongrattanasiri ◽  
F. Javier García de Abajo
Keyword(s):  
Cross Sections ◽  
Near Infrared ◽  
Near Field ◽  
Field Enhancement ◽  
High Sensitivity ◽  
Quantum Mechanical ◽  
Single Electrons ◽  
Electromagnetic Simulations ◽  
Highly Sensitive ◽  
Infrared Wavelengths

AbstractPlasmons produce large confinement and enhancement of light that enable applications as varied as cancer therapy and catalysis. Adding to these appealing properties, graphene has emerged as a robust, electrically tunable material exhibiting plasmons that strongly depend on the density of doping charges. Here we show that adding a single electron to a graphene nanoisland consisting of hundreds or thousands of atoms switches on infrared plasmons that were previously absent from the uncharged structure. Remarkably, the addition of each further electron produces a dramatic frequency shift. Plasmons in these islands are shown to be tunable down to near infrared wavelengths. These phenomena are highly sensitive to carbon edges. Specifically, armchair nanotriangles display sharp plasmons that are associated with intense near-field enhancement, as well as absorption cross-sections exceeding the geometrical area occupied by the graphene. In contrast, zigzag triangles do not support these plasmons. Our conclusions rely on realistic quantum-mechanical calculations, which are in ostensible disagreement with classical electromagnetic simulations, thus revealing the quantum nature of the plasmons. This study shows a high sensitivity of graphene nanoislands to elementary charges, therefore emphasizing their great potential for novel nano-optoelectronics applications.

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