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1
Lerch, Sarah, and Björn M. Reinhard. "Spectral signatures of charge transfer in assemblies of molecularly-linked plasmonic nanoparticles." International Journal of Modern Physics B 31, no. 24 (September 30, 2017): 1740002. http://dx.doi.org/10.1142/s0217979217400021.
Повний текст джерелаАнотація:
Self-assembly of functionalized nanoparticles (NPs) provides a unique class of nanomaterials for exploring and utilizing quantum-plasmonic effects that occur if the interparticle separation between NPs approaches a few nanometers and below. We review recent theoretical and experimental studies of plasmon coupling in self-assembled NP structures that contain molecular linkers between the NPs. Charge transfer through the interparticle gap of an NP dimer results in a significant blue-shift of the bonding dipolar plasmon (BDP) mode relative to classical electromagnetic predictions, and gives rise to new coupled plasmon modes, the so-called charge transfer plasmon (CTP) modes. The blue-shift of the plasmon spectrum is accompanied by a weakening of the electromagnetic field in the gap of the NPs. Due to an optical far-field signature that is sensitive to charge transfer across the gap, plasmonic molecules represent a sensor platform for detecting and characterizing gap conductivity in an optical fashion and for characterizing the role of molecules in facilitating the charge transfer across the gap.
2
Aigner, Andreas, Stefan Maier, and Haoran Ren. "Topological-Insulator-Based Gap-Surface Plasmon Metasurfaces." Photonics 8, no. 2 (February 4, 2021): 40. http://dx.doi.org/10.3390/photonics8020040.
Повний текст джерелаАнотація:
Topological insulators (TIs) have unique highly conducting symmetry-protected surface states while the bulk is insulating, making them attractive for various applications in condensed matter physics. Recently, topological insulator materials have been tentatively applied for both near- and far-field wavefront manipulation of electromagnetic waves, yielding superior plasmonic properties in the ultraviolet (UV)-to-visible wavelength range. However, previous reports have only demonstrated inefficient wavefront control based on binary metasurfaces that were digitalized on a TI thin film or non-directional surface plasmon polariton (SPP) excitation. Here, we numerically demonstrated the plasmonic capabilities of the TI Bi2Te3 as a material for gap–surface plasmon (GSP) metasurfaces. By employing the principle of the geometric phase, a far-field beam-steering metasurface was designed for the visible spectrum, yielding a cross-polarization efficiency of 34% at 500 nm while suppressing the co-polarization to 0.08%. Furthermore, a birefringent GSP metasurface design was studied and found to be capable of directionally exciting SPPs depending on the incident polarization. Our work forms the basis for accurately controlling the far- and near-field responses of TI-based GSP metasurfaces in the visible spectral range.
3
El-Aasser, Mostafa A., and Safwat A. Mahmoud. "Spectral Properties of Plasmonic Vertical Nano-Gap Array Resonators." Journal of Nanoelectronics and Optoelectronics 14, no. 3 (March 1, 2019): 420–24. http://dx.doi.org/10.1166/jno.2019.2506.
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Hooshmand, Nasrin, and Mostafa A. El-Sayed. "Collective multipole oscillations direct the plasmonic coupling at the nanojunction interfaces." Proceedings of the National Academy of Sciences 116, no. 39 (September 5, 2019): 19299–304. http://dx.doi.org/10.1073/pnas.1909416116.
Повний текст джерелаАнотація:
We present a systematic study of the effect of higher-multipolar order plasmon modes on the spectral response and plasmonic coupling of silver nanoparticle dimers at nanojunction separation and introduce a coupling mechanism. The most prominent plasmonic band within the extinction spectra of coupled resonators is the dipolar coupling band. A detailed calculation of the plasmonic coupling between equivalent particles suggests that the coupling is not limited to the overlap between the main bands of individual particles but can also be affected by the contribution of the higher-order modes in the multipolar region. This requires an appropriate description of the mechanism that goes beyond the general coupling phenomenon introduced as the plasmonic ruler equation in 2007. In the present work, we found that the plasmonic coupling of nearby Ag nanocubes does not only depend on the plasmonic properties of the main band. The results suggest the decay length of the higher-order plasmon mode is more sensitive to changes in the magnitude of the interparticle axis and is a function of the gap size. For cubic particles, the contribution of the higher-order modes becomes significant due to the high density of oscillating dipoles localized on the corners. This gives rise to changes in the decay length of the plasmonic ruler equation. For spherical particles, as the size of the particle increases (i.e., ≥80 nm), the number of dipoles increases, which results in higher dipole–multipole interactions. This exhibits a strong impact on the plasmonic coupling, even at long separation distances (20 nm).
5
de Nijs, Bart, Richard W. Bowman, Lars O. Herrmann, Felix Benz, Steve J. Barrow, Jan Mertens, Daniel O. Sigle, et al. "Unfolding the contents of sub-nm plasmonic gaps using normalising plasmon resonance spectroscopy." Faraday Discussions 178 (2015): 185–93. http://dx.doi.org/10.1039/c4fd00195h.
Повний текст джерелаАнотація:
Plasmonic coupling of gold nanoparticles to a gold surface creates intense plasmonic hot spots with large electromagnetic field-enhancements within the cavity formed by the two metallic surfaces. The localised field in such structures is extremely sensitive to morphological fluctuations and subtle changes in the dielectric properties of the cavity contents. Here, we present an optical method that pins down the properties of the gap contents with high sensitivity, termed normalising plasmon resonance (NPR) spectroscopy. We use this on a variety of ultrathin molecular spacers such as filled and empty cucurbiturils, and graphene. Clear differences in the spectral positions and intensities of plasmonic modes observed in the scattering spectrum resolve thickness differences of 0.1 nm, and refractive index changes from molecular filling.
6
Park, Jongkyoon, Hyunsoo Lee, Alexander Gliserin, Kyujung Kim, and Seungchul Kim. "Spectral Shifting in Extraordinary Optical Transmission by Polarization-Dependent Surface Plasmon Coupling." Plasmonics 15, no. 2 (November 16, 2019): 489–94. http://dx.doi.org/10.1007/s11468-019-01058-w.
Повний текст джерелаАнотація:
AbstractNanoapertures in a metallic film exhibit extraordinary optical transmission (EOT) owing to the surface plasmon resonance. Their transmission properties are known to be dependent on the structural parameters of the nanoapertures. In addition, the polarization of light has also a crucial influence on the transmission spectrum. In this study, we numerically found that the polarization state is a sensitive parameter in plasmonic EOT only when the gap size between triangular nanoapertures is less than ~ 20 nm. For a polarization of the light perpendicular to the axis between the nanoapertures, the optical transmission spectrum is nonlinearly redshifted with decreasing gap size. This spectral shifting of the transmission has potential applications for active optical filters, which can be manipulated by the polarization of light or by adjusting the gap size.
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Li, Guang-Can, Qiang Zhang, Stefan A. Maier, and Dangyuan Lei. "Plasmonic particle-on-film nanocavities: a versatile platform for plasmon-enhanced spectroscopy and photochemistry." Nanophotonics 7, no. 12 (November 26, 2018): 1865–89. http://dx.doi.org/10.1515/nanoph-2018-0162.
Повний текст джерелаАнотація:
AbstractMetallic nanostructures with nanometer gaps support hybrid plasmonic modes with an extremely small mode volume and strong local field intensity, which constitutes an attractive plasmonic platform for exploring novel light-matter interaction phenomena at the nanoscale. Particularly, the plasmonic nanocavity formed by a metal nanoparticle closely separated from a thin metal film has received intensive attention in the nanophotonics community, largely attributed to its ease of fabrication, tunable optical properties over a wide spectral range, and the ultrastrong confinement of light at the small gap region scaled down to sub-nanometer. In this article, we review the recent exciting progress in exploring the plasmonic properties of such metal particle-on-film nanocavities (MPoFNs), as well as their fascinating applications in the area of plasmon-enhanced imaging and spectroscopies. We focus our discussion on the experimental fabrication and optical characterization of MPoFNs and the theoretical interpretation of their hybridized plasmon modes, with particular interest on the nanocavity-enhanced photoluminescence and Raman spectroscopies, as well as photocatalysis and molecular nanochemistry.
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Zhang, Tianyue, Jian Xu, Zi-Lan Deng, Dejiao Hu, Fei Qin, and Xiangping Li. "Unidirectional Enhanced Dipolar Emission with an Individual Dielectric Nanoantenna." Nanomaterials 9, no. 4 (April 18, 2019): 629. http://dx.doi.org/10.3390/nano9040629.
Повний текст джерелаАнотація:
Light manipulation at the nanoscale is the vanguard of plasmonics. Controlling light radiation into a desired direction in parallel with high optical signal enhancement is still a challenge for designing ultracompact nanoantennas far below subwavelength dimensions. Here, we theoretically demonstrate the unidirectional emissions from a local nanoemitter coupled to a hybrid nanoantenna consisting of a plasmonic dipole antenna and an individual silicon nanorod. The emitter near-field was coupled to the dipolar antenna plasmon resonance to achieve a strong radiative decay rate modification, and the emitting plasmon pumped the multipoles within the silicon nanorod for efficient emission redirection. The hybrid antenna sustained a high forward directivity (i.e., a front-to-back ratio of 30 dB) with broadband operating wavelengths in the visible range (i.e., a spectral bandwidth of 240 nm). This facilitated a large library of plasmonic nanostructures to be incorporated, from single element dipole antennas to gap antennas. The proposed hybrid optical nanorouter with ultracompact structural dimensions of 0.08 λ2 was capable of spectrally sorting the emission from the local point source into distinct far-field directions, as well as possessing large emission gains introduced by the nanogap. The distinct features of antenna designs hold potential in the areas of novel nanoscale light sources, biosensing, and optical routing.
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Gerislioglu, Burak, and Arash Ahmadivand. "Functional Charge Transfer Plasmon Metadevices." Research 2020 (January 30, 2020): 1–18. http://dx.doi.org/10.34133/2020/9468692.
Повний текст джерелаАнотація:
Reducing the capacitive opening between subwavelength metallic objects down to atomic scales or bridging the gap by a conductive path reveals new plasmonic spectral features, known as charge transfer plasmon (CTP). We review the origin, properties, and trending applications of this modes and show how they can be well-understood by classical electrodynamics and quantum mechanics principles. Particularly important is the excitation mechanisms and practical approaches of such a unique resonance in tailoring high-response and efficient extreme-subwavelength hybrid nanophotonic devices. While the quantum tunneling-induced CTP mode possesses the ability to turn on and off the charge transition by varying the intensity of an external light source, the excited CTP in conductively bridged plasmonic systems suffers from the lack of tunability. To address this, the integration of bulk plasmonic nanostructures with optothermally and optoelectronically controllable components has been introduced as promising techniques for developing multifunctional and high-performance CTP-resonant tools. Ultimate tunable plasmonic devices such as metamodulators and metafilters are thus in prospect.
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Mennucci, Carlo, Debasree Chowdhury, Giacomo Manzato, Matteo Barelli, Roberto Chittofrati, Christian Martella, and Francesco Buatier de Mongeot. "Large-area flexible nanostripe electrodes featuring plasmon hybridization engineering." Nano Research 14, no. 3 (October 21, 2020): 858–67. http://dx.doi.org/10.1007/s12274-020-3125-x.
Повний текст джерелаАнотація:
AbstractMultifunctional flexible Au electrodes based on one-dimensional (1D) arrays of plasmonic gratings are nanofabricated over large areas with an engineered variant of laser interference lithography optimized for low-cost transparent templates. Au nanostripe (NS) arrays achieve sheet resistance in the order of 20 Ohm/square on large areas (∼ cm2) and are characterized by a strong and dichroic plasmonic response which can be easily tuned across the visible (VIS) to near-infrared (NIR) spectral range by tailoring their cross-sectional morphology. Stacking vertically a second nanostripe, separated by a nanometer scale dielectric gap, we form near-field coupled Au/SiO2/Au dimers which feature hybridization of their localized plasmon resonances, strong local field-enhancements and a redshift of the resonance towards the NIR range. The possibility to combine excellent transport properties and optical transparency on the same plasmonic metasurface template is appealing in applications where low-energy photon management is mandatory like e.g., in plasmon enhanced spectroscopies or in photon harvesting for ultrathin photovoltaic devices. The remarkable lateral order of the plasmonic NS gratings provides an additional degree of freedom for tailoring the optical response of the multifunctional electrodes via the excitation of surface lattice resonances, a Fano-like coupling between the broad localised plasmonic resonances and the collective sharp Rayleigh modes.
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Do, Yun Seon. "Efficient Design Method for Plasmonic Filter for Tuning Spectral Selectivity." Crystals 10, no. 6 (June 23, 2020): 531. http://dx.doi.org/10.3390/cryst10060531.
Повний текст джерелаАнотація:
Nano-structure-based color technologies have been reported as alternatives for conventional pigment- or dye-based color filters due to their simple design methods and durable characteristics. Since structure-based optical resonances accompany multiple resonance modes, spectral selectivity could be degraded. In this work, a simple and effective design of a plasmonic color filter that combines the plasmonic filter with one-dimensional photonic crystals. The introduced photonic crystal provides a photonic band gap, and it helps in suppressing the undesirable transmission peaks of the plasmonic color filter that originates from higher order resonance modes. Finally, the proposed design achieves high color purity. In addition, the simplicity of the design makes it both suitable for large-area fabrication and cost effective. This work is expected to provide a practical alternative to traditional color filters.
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Pidgayko, Dmitry, Ilya Deriy, Vladimir Fedorov, Alexey Mozharov, Ivan Mukhin, Yuriy Zadiranov, Mihail Petrov, Anton Samusev, and Andrey Bogdanov. "Second harmonic generation in hybrid GaP/Au nanocylinders." Journal of Physics: Conference Series 2015, no. 1 (November 1, 2021): 012172. http://dx.doi.org/10.1088/1742-6596/2015/1/012172.
Повний текст джерелаАнотація:
Abstract To date, nanoscale dielectric and plasmonic systems with a nonlinear response are of great interest to researchers. This is due to a wide range of their potential applications in nonlinear optical converters and optical communication systems. The fundamental problem of nanoscale frequency converters is the low efficiency of nonlinear optical generation. The reason for this is that the main mechanism for increasing the efficiency of nonlinear signal generation via phase matching is not available at scales smaller than the wavelength. Here, we experimentally investigate the generation of the second optical harmonic in hybrid GaP/Au nanoparticles resonantly enhanced with plasmonic and Mie resonances. Using dark-field spectroscopy, it is shown that nanoantennas support a series of optical resonances in the visible range, the spectral position of which is in good agreement with the numerical simulation. We measured the second harmonic generation spectrum, with sharp resonances which is in accordance with linear scattering. Finally, the dependence of the second harmonic optical signal on the polarization is measured.
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Braun, Kai, Florian Laible, Otto Hauler, Xiao Wang, Anlian Pan, Monika Fleischer, and Alfred J. Meixner. "Active optical antennas driven by inelastic electron tunneling." Nanophotonics 7, no. 9 (September 7, 2018): 1503–16. http://dx.doi.org/10.1515/nanoph-2018-0080.
Повний текст джерелаАнотація:
AbstractIn this review, we focus on the experimental demonstration of enhanced emission from single plasmonic tunneling junctions consisting of coupled nano antennas or noble metal tips on metallic substrates in scanning tunneling microscopy. Electromagnetic coupling between resonant plasmonic oscillations of two closely spaced noble metal particles leads to a strongly enhanced optical near field in the gap between. Electron beam lithography or wet chemical synthesis enables accurate control of the shape, aspect ratio, and gap size of the structures, which determines the spectral shape, position, and width of the plasmonic resonances. Many emerging nano-photonic technologies depend on the careful control of such localized resonances, including optical nano antennas for high-sensitivity sensors, nanoscale control of active devices, and improved photovoltaic devices. The results discussed here show how optical enhancement inside the plasmonic cavity can be further increased by a stronger localization via tunneling. Inelastic electron tunneling emission from a plasmonic junction allows for new analytical applications. Furthermore, the reviewed concepts represent the basis for novel ultra-small, fast, optically, and electronically switchable devices and could find applications in high-speed signal processing and optical telecommunications.
14
Devaraj, Vasanthan, Jong-Min Lee, Ye-Ji Kim, Hyuk Jeong, and Jin-Woo Oh. "Engineering Efficient Self-Assembled Plasmonic Nanostructures by Configuring Metallic Nanoparticle’s Morphology." International Journal of Molecular Sciences 22, no. 19 (September 30, 2021): 10595. http://dx.doi.org/10.3390/ijms221910595.
Повний текст джерелаАнотація:
We reveal the significance of plasmonic nanoparticle’s (NP) shape and its surface morphology en route to an efficient self-assembled plasmonic nanoparticle cluster. A simplified model is simulated in the form of free-space dimer and trimer nanostructures (NPs in the shape of a sphere, cube, and disk). A ~200% to ~125% rise in near-field strength (gap mode enhancement) is observed for spherical NPs in comparison with cubical NPs (from 2 nm to 8 nm gap sizes). Full-width three-quarter maximum reveals better broad-spectral optical performance in a range of ~100 nm (dimer) and ~170 nm (trimer) from spherical NPs as compared to a cube (~60 nm for dimer and trimer). These excellent properties for sphere-based nanostructures are merited from its dipole mode characteristics.
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Yashima, Shiho, Hiroshi Sugimoto, Hiroyuki Takashina, and Minoru Fujii. "Fluorescence Enhancement and Spectral Shaping of Silicon Quantum Dot Monolayer by Plasmonic Gap Resonances." Journal of Physical Chemistry C 120, no. 50 (December 9, 2016): 28795–801. http://dx.doi.org/10.1021/acs.jpcc.6b09124.
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Zhang, Ying, and Hui Fang. "Surface-enhanced photoacoustic wave generation from light absorbers located in the gap of high-refractive-index dielectric nanoparticles." Applied Physics Letters 121, no. 21 (November 21, 2022): 213701. http://dx.doi.org/10.1063/5.0122226.
Повний текст джерелаАнотація:
Plasmonic nanoparticles, such as Au nanoparticles, have been used as effective exogeneous contrast agents in photoacoustic imaging. However, using these particles to enhance photoacoustic wave generation from other light absorbers is difficult because the signal is overwhelmed by the signal from plasmonic nanoparticles themselves. In this study, we realized the surface-enhanced photoacoustic effect by using high-refractive-index dielectric nanoparticles in their ultralow light absorption Ohmic-loss wavelength band. We performed finite element method simulation on a model with gallium phosphide nanorod dimmer and light absorbers in the dimmer gap. The Au nanowire, carbon nanotube, and nanotube filled with melanin molecules were sequentially considered as the light absorber. It is found that a photoacoustic wave surface enhancement factor of approximately 10 was achieved and the enhanced photoacoustic wave ensures the photoacoustic spectral signature of the light absorber. The potential of optimization for boosting enhancement factors was further analyzed. These results can provide considerable insight into molecular photoacoustic sensing and imaging.
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Bhardwaj, Priyanka, Manidipa Roy, and Sanjay Kumar Singh. "Gold Coated VO2 Nanogratings Based Plasmonic Switches." Trends in Sciences 19, no. 1 (January 1, 2022): 1721. http://dx.doi.org/10.48048/tis.2022.1721.
Повний текст джерелаАнотація:
This paper presents 2 dimensional (2D) and 1 dimensional (1D) gold (Au) coated VO2 (Vanadium Dioxide) nanogratings based tunable plasmonic switch. VO2 is a phase changing material and hence exhibits phase transition from semiconductor to metallic phase approximately at 67 ºC or 340 K (critical temperature) which can be achieved by exposure to IR radiation, application of voltage, heating, etc. and there is a huge contrast between optical properties of its metallic and insulating phases and hence that can be utilized to implement VO2 based optical switches. These VO2 based gratings couple the incident optical radiation to plasmonic waveguide modes which in turn leads to high electromagnetic field enhancement in the gaps between the nanogratings. The proposed Au coated VO2 nanogratings can be fabricated by using current state of art fabrication techniques and provides switchability of the order of femtoseconds. Hence the optical switching explained in our paper can be used fast switching applications. For an optimum switch our aim is to maximize its differential reflectance spectra between the 2 states of VO2, i.e., metallic and semiconductor phases. Rigorous Coupled Wave Analysis (RCWA) reveals that wavelengths for maximum differential reflectance can be optimized over a large spectral regime by varying various parameters of nanogratings for example groove height (h), width (w), gap (g) between the gratings, and thickness (t) of Au coating over VO2 by simulation using RCWA for maximum differential reflectance between VO2 metal and semiconductor phase, i.e., the switching wavelengths can be tuned by varying grating parameters and thus we can have optimum optical switch.
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Hu, Jinyong, Chuxuan Tan, Wangdi Bai, Yiming Li, Qi Lin, and Lingling Wang. "Dielectric nanocavity-coupled surface lattice resonances for high-efficiency plasmonic sensing." Journal of Physics D: Applied Physics 55, no. 7 (November 9, 2021): 075105. http://dx.doi.org/10.1088/1361-6463/ac31f2.
Повний текст джерелаАнотація:
Abstract Surface lattice resonances (SLRs) arising in metal nanostructure arrays have shown tremendous application prospects in the field of plasmonic biosensing. However, these SLRs still suffer from poor optical properties, such as broad linewidth or weak resonance intensity that is especially excited under normal incidence and asymmetric environments, which hinder further practical applications. Herein, we theoretically propose an effective strategy to tailor the SLRs performance of metal nanostructure arrays by introducing a dielectric nanocavity. Originating from the strong interference between the in-plane lattice resonance mode and plasmonic gap cavity modes, the dielectric nanocavity-mediated gold nanostructure arrays exhibit both narrow spectral features with a linewidth of ∼8.2 nm and strong resonance intensity with absorbance amplitude exceeding 95%, even though under normal incidence and asymmetric environment excitation. The simulation results then show that the sensitivity and the figure of merit can reach up to 527.5 nm RIU−1 and 64.3, respectively, as for plasmonic refractive index sensing. This work not only paves the way toward the achievement of effective control of in-plane SLRs, but also provides a potentially attractive candidate for the development of high-efficiency plasmonic sensors.
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Shin, Eunso, Young Jin Lee, Hyoungjoo Nam, and Soon-Hong Kwon. "Hydrogen Sensor: Detecting Far-Field Scattering of Nano-Blocks (Mg, Ag, and Pd)." Sensors 20, no. 14 (July 9, 2020): 3831. http://dx.doi.org/10.3390/s20143831.
Повний текст джерелаАнотація:
Hydrogen sensor technologies have been rapidly developing. For effective and safe sensing, we proposed a hydrogen sensor composed of magnesium (Mg), silver (Ag), and palladium (Pd) nano-blocks that overcomes the spectral resolution limit. This sensor exploited the properties of Mg and Pd when absorbing hydrogen. Mg became a dielectric material, and the atomic lattice of Pd expanded. These properties led to changes in the plasmonic gap mode between the nano-blocks. Owing to the changing gap mode, the far-field scattering pattern significantly changed with the hydrogen concentration. Thus, sensing the hydrogen concentration was able to be achieved simply by detecting the far-field intensity at a certain angle for incident light with a specific wavelength.
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Yousif, Bedir B., and Ahmed S. Samra. "Modeling of Optical Nanoantennas." Physics Research International 2012 (November 8, 2012): 1–10. http://dx.doi.org/10.1155/2012/321075.
Повний текст джерелаАнотація:
The optical properties of plasmonic nanoantennas are investigated in detail using the finite integration technique (FIT). The validity of this technique is verified by comparison to the exact solution generalized Mie method (GMM). The influence of the geometrical parameters (antenna length, gap dimension, and shapes) on the antenna field enhancement and spectral response is discussed. Localized surface plasmon resonances of Au (gold) dimers nanospheres, bowtie, and aperture bowtie nanoantennas are modeled. The enhanced field is equivalent to a strong light spot which can lead to the resolution improvement of the microscopy and optical lithography, thus increasing the optical data storage capacity. Furthermore, the sensitivity of the antennas to index changes of the environment and substrate is investigated in detail for biosensing applications. We confirm that our approach yields an exact correspondence with GMM theory for Au dimers nanospheres at gap dimensions 5 nm and 10 nm but gives an approximation error of less than 1.37% for gap dimensions 1 nm and 2 nm with diameters approaching 80 nm. In addition, the far-field characteristics of the aperture bowtie nanoantenna such as directivity and gain are studied. The promising results of this study may have useful potential applications in near-field sample detection, optical microscopy, and so forth.
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Krasavin, Alexey V., Pan Wang, Mazhar E. Nasir, Yunlu Jiang, and Anatoly V. Zayats. "Tunneling-induced broadband and tunable optical emission from plasmonic nanorod metamaterials." Nanophotonics 9, no. 2 (February 25, 2020): 427–34. http://dx.doi.org/10.1515/nanoph-2019-0411.
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AbstractWe demonstrate a metamaterial platform for electrically driven broadband light emission induced by electron tunneling. Both the Fabry-Perot and waveguided modes of the metamaterial slab as well the plasmonic mode of the tunneling gap are identified as contributing to shaping the emission spectrum. This opens up an opportunity to design the spectrum and polarization of the emitted light by tuning the metamaterial modes via the geometric parameters of the nanostructure throughout the visible and near-infrared spectral ranges. The efficient coupling of the tunneling-induced emission to the waveguided modes is beneficial for the development of integrated incoherent light sources, while the outcoupled emission provides a source of free-space radiation. The demonstrated incoherent nanoscale light sources may find applications in the development of integrated opto-electronic circuits, optical sensing platforms, imaging, and metrology.
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Zhu, Jian, Shuang Zhang, Guo-jun Weng, Jian-jun Li, and Jun-wu Zhao. "The morphology regulation and plasmonic spectral properties of Au@AuAg yolk-shell nanorods with controlled interior gap." Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy 236 (August 2020): 118343. http://dx.doi.org/10.1016/j.saa.2020.118343.
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Hu, Chai, Taige Liu, Kewei Liu, JIashuo Shi, Mao Ye, Zhe Wang, and Xinyu Zhang. "Plasmonic nano-focusing enhancement of nano-rhombus-shaped resonators in the sub-diffraction limit for highly efficient lightwave collection." Optical Materials Express 12, no. 8 (August 1, 2022): 3313. http://dx.doi.org/10.1364/ome.468888.
Повний текст джерелаАнотація:
A kind of optical metasurface composed of arrayed nano-rhombus-shaped resonators is proposed. The metasurface as an arrayed optical antenna for highly efficient collecting incident lightwaves, can be utilized to perform light absorption and nano-focusing. The absorption peak can be modulated in a relatively broad spectral range only by adjusting the thickness of the functioned silver film coated. For the same thickness parameter, the key surface plasmons are effectively excited by incident lightwaves polarized along the short axis of the nano-rhombus can broaden the modulated spectral range compared to that along the long axis. Compared with a single nano-rhombus-aperture, a double nano-rhombus-shaped composite architecture (DNRCA) predicts a higher light absorption peak and a stronger near-field lightwave converging. The resonators present a dipole of resonant oscillation through compressing incident lightwaves into a resonant cavity with a very small gap, and then the net charges distribute over two opposite sidewalls of a single cavity. The coupling oscillation becomes stronger with the narrower air gap of the cavity. The achieved near-field light converging presents a typical focusing spot with a minimum size of ∼21 nm, which is one order of magnitude smaller than the incident wavelength of 633 nm, so as to greatly break the traditional diffraction limit.
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Do, Thi-Nga, Godfrey Gumbs, Danhong Huang, Bui D. Hoi, and Po-Hsin Shih. "Role Played by Edge-Defects in the Optical Properties of Armchair Graphene Nanoribbons." Nanomaterials 11, no. 12 (November 28, 2021): 3229. http://dx.doi.org/10.3390/nano11123229.
Повний текст джерелаАнотація:
We explore the implementation of specific optical properties of armchair graphene nanoribbons (AGNRs) through edge-defect manipulation. This technique employs the tight-binding model in conjunction with the calculated absorption spectral function. Modification of the edge states gives rise to the diverse electronic structures with striking changes in the band gap and special flat bands at low energy. The optical-absorption spectra exhibit unique excitation peaks, and they strongly depend on the type and period of the edge extension. Remarkably, there exist the unusual transition channels associated with the flat bands for selected edge-modified systems. We discovered the special rule governing how the edge-defect influences the electronic and optical properties in AGNRs. Our theoretical prediction demonstrates an efficient way to manipulate the optical properties of AGNRs. This might be of importance in the search for suitable materials designed to have possible technology applications in nano-optical, plasmonic and optoelectronic devices.
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Liao, Yan-Juan, Jing-Nan Huang, Jia-Yang Guo, and Shao-Ji Jiang. "Realistic FDTD Simulations of Plasmonic Properties on Ag Columnar Thin Films as SERS Biosensor." Nano 11, no. 10 (September 29, 2016): 1650113. http://dx.doi.org/10.1142/s1793292016501137.
Повний текст джерелаАнотація:
Noble metal sculptured thin films are of great interest during last decade as excellent surface-enhanced Raman scattering (SERS) substrates due to remarkable plasmonic properties in the visible and near-infrared range. In this work, Ag columnar thin films (Ag-CTFs) have been prepared by the glancing angle deposition technique. Finite-difference time-domain simulations has been utilized to study plasmonic properties of Ag-CTFs with a more accurate model based on binary scanning electron microscope (SEM) images by taking account of the shape irregularities, size distributions and random arrangement. The calculated absorption spectra based on the model of binarized SEM images show the best agreement with the measured spectra compared with models of periodic array with a regular shape. The near-field plasmonic properties are simulated based on the verified model. The distributions of electric field enhancement and hot spots are confirmed to be spectral and polarization dependent. There are multiple resonance peaks from visible to near-infrared and multiple eigenmodes coexist at the same wavelength and electric field enhancement are mainly excited by the polarized light vertical to the gap orientation. The electric field enhancement is found to distribute unevenly in the films with surface-localized feature. The equations to calculate the simulation SERS enhancement factor (EF) and total number of hot spots (tHN) are modified according to the above discussions. The experimental SERS EFs are on the order of 107–108, which indicates the high sensitivity of the films and the simulation SERS EFs and tHNs show good agreement with the experimental EFs. It is found that the SERS performance of Ag-CTFs is decided by both the cross-section structural characteristics and film thickness, which affect the electric filed enhancement and number of adsorbed molecules, respectively. Our work could be helpful in understanding the SERS mechanism and useful to the optimization of metal sculptured thin films for designing SERS biosensor.
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Khan, Taj Muhammad, Shahab Ud-Din Khan, Muhammad Raffi, and Riaz Khan. "Theoretical–Computational Study of Atmospheric DBD Plasma and Its Utility for Nanoscale Biocompatible Plasmonic Coating." Molecules 26, no. 16 (August 23, 2021): 5106. http://dx.doi.org/10.3390/molecules26165106.
Повний текст джерелаАнотація:
In this study, time-dependent, one-dimensional modeling of a surface dielectric barrier discharge (SDBD) device, driven by a sinusoidal voltage of amplitude 1–3 kV at 20 kHz, in argon is described. An SDBD device with two Cu-stripe electrodes, covered by the quartz dielectric and with the discharge gap of 20 × 10−3 m, was assumed, and the time-dependent, one-dimensional discharge parameters were simulated versus time across the plasma gap. The plasma device simulated in the given arrangement was constructed and used for biocompatible antibacterial/antimicrobial coating of plasmonic particle aerosol and compared with the coating strategy of the DBD plasma jet. Simulation results showed discharge consists of an electrical breakdown, occurring in each half-cycle of the AC voltage with an electron density of 1.4 × 1010 cm−3 and electric field strength of 4.5 × 105 Vm−1. With SDBD, the surface coating comprises spatially distributed particles of mean size 29 (11) nm, while with argon plasma jet, the nanoparticles are aggregated in clusters that are three times larger in size. Both coatings are crystalline and exhibit plasmonic features in the visible spectral region. It is expected that the particle aerosols are collected under the ionic wind, induced by the plasma electric fields, and it is assumed that this follows the dominant charging mechanisms of ions diffusion. The cold plasma strategy is appealing in a sense; it opens new venues at the nanoscale to deal with biomedical and surgical devices in a flexible processing environment.
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Verma, Sneha, Souvik Ghosh, and B. M. A. Rahman. "All-Opto Plasmonic-Controlled Bulk and Surface Sensitivity Analysis of a Paired Nano-Structured Antenna with a Label-Free Detection Approach." Sensors 21, no. 18 (September 14, 2021): 6166. http://dx.doi.org/10.3390/s21186166.
Повний текст джерелаАнотація:
Gold nanoantennas have been used in a variety of biomedical applications due to their attractive electronic and optical properties, which are shape- and size-dependent. Here, a periodic paired gold nanostructure exploiting surface plasmon resonance is proposed, which shows promising results for Refractive Index (RI) detection due to its high electric field confinement and diffraction limit. Here, single and paired gold nanostructured sensors were designed for real-time RI detection. The Full-Width at Half-Maximum (FWHM) and Figure-Of-Merit (FOM) were also calculated, which relate the sensitivity to the sharpness of the peak. The effect of different possible structural shapes and dimensions were studied to optimise the sensitivity response of nanosensing structures and identify an optimised elliptical nanoantenna with the major axis a, minor axis b, gap between the pair g, and heights h being 100 nm, 10 nm, 10 nm, and 40 nm, respectively. In this work, we investigated the bulk sensitivity, which is the spectral shift per refractive index unit due to the change in the surrounding material, and this value was calculated as 526–530 nm/RIU, while the FWHM was calculated around 110 nm with a FOM of 8.1. On the other hand, the surface sensing was related to the spectral shift due to the refractive index variation of the surface layer near the paired nanoantenna surface, and this value for the same antenna pair was calculated as 250 nm/RIU for a surface layer thickness of 4.5 nm.
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Yang, Qi-Li, Xing-Fang Zhang, Feng-Shou Liu, Xin Yan, and Lan-Ju Liang. "Multiple Fano resonances in gold split ring disk dimers." Acta Physica Sinica 71, no. 2 (2022): 027802. http://dx.doi.org/10.7498/aps.71.20210855.
Повний текст джерелаАнотація:
A plasmonic dimer composed of a gold split ring and a gold disk is proposed. The scattering spectra and electromagnetic field distributions on the surface of the dimer are calculated by the finite difference time domain method, and the effects of split gap orientation and structural symmetry breaking of the ring on Fano resonance characteristics are theoretically investigated in detail. The results show the multiple Fano resonances that can be formed due to the destructive interference between the electric dipole mode of the disk and multiple multipolar modes of the split ring, and the red shift when the symmetry breaking of the split ring is broken. When the split gap of the ring is parallel to the interparticle axis of the dimer, multiple Fano resonances based on the odd-order mode and the even-order mode of the split ring can be generated, and more even-order Fano resonances can be formed due to the further symmetry breaking of the split ring. In addition, a more refined scattering spectrum can be obtained as the ring internal surface moves far away from the disk along the interparticle axis. On the other hand, Fano resonances based on the lower order multipolar modes of the ring can be increased as they move away from the split gap. When the split gap of the ring is perpendicular to the interparticle axis of the dimer, only the even-order Fano resonances can be excited, and these resonances increase with the ring internal surface going away from the disk no matter whether the split gap of the ring faces the disk or not. As the structural symmetry of the dimer is further broken due to the ring internal surface moving along the split gap direction, the odd-order Fano resonance can be successfully produced in the dimer with the split gap coming back to the disk, at the same time, the even-order Fano resonances are gradually weaken perhaps due to the complicated competitive behaviors of spectral overlapping between the dipole mode of the disk and multipolar mode of the ring in energy. However, there is no odd-order Fano resonance appearing in the dimer with the split gap facing the disk except for a slightly increased even-order Fano resonance, as the structural symmetry of the dimer is further broken. These results are expected to be useful in designing multiple Fano controllable split ring disk dimers and also developing the application of multiwavelength micro-nano photonics.
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Fauzi, Nurul Illya Muhamad, Yap Wing Fen, Faten Bashar Kamal Eddin, and Wan Mohd Ebtisyam Mustaqim Mohd Daniyal. "Structural and Optical Properties of Graphene Quantum Dots−Polyvinyl Alcohol Composite Thin Film and Its Potential in Plasmonic Sensing of Carbaryl." Nanomaterials 12, no. 22 (November 21, 2022): 4105. http://dx.doi.org/10.3390/nano12224105.
Повний текст джерелаАнотація:
In this study, graphene quantum dots (GQDs) and polyvinyl alcohol (PVA) composite was prepared and then coated on the surface of gold thin film via the spin coating technique. Subsequently, Fourier transform infrared spectroscopy (FT-IR), atomic force microscopy (AFM), and ultraviolet-visible spectroscopy (UV–Vis) were adopted to understand the structure, surface morphology, and optical properties of the prepared samples. The FT-IR spectral analysis revealed important bands, such as O–H stretching, C=O stretching, C-H stretching, and O=C=O stretching vibrations. The surface roughness of the GQDs-PVA composite thin film was found to be increased after exposure to carbaryl. On the other hand, the optical absorbance of the GQDs-PVA thin film was obtained and further analysis was conducted, revealing a band gap Eg value of 4.090 eV. The sensing potential of the thin film was analyzed using surface plasmon resonance (SPR) spectroscopy. The findings demonstrated that the developed sensor’s lowest detection limit for carbaryl was 0.001 ppb, which was lower than that previously reported, i.e., 0.007 ppb. Moreover, other sensing performance parameters, such as full width at half maximum, detection accuracy, and signal-to-noise ratio, were also investigated to evaluate the sensor’s efficiency.
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Alizade E.H. "Study of plasmon resonance in Bi-=SUB=-2-=/SUB=-Se-=SUB=-3-=/SUB=- and Sb-=SUB=-2-=/SUB=-Te-=SUB=-3-=/SUB=- by infrared spectral ellipsometry." Optics and Spectroscopy 132, no. 2 (2022): 248. http://dx.doi.org/10.21883/eos.2022.02.53214.2599-21.
Повний текст джерелаАнотація:
In the infrared region of the spectrum (IR), the optical properties of single-crystal samples of narrow-gap degenerate semiconductors Bi2Se3 and Sb2Te3 are investigated by infrared spectral ellipsometry (SE). The transport properties of the Drude fitting of dielectric functions obtained by spectroscopic ellipsometry are studied. The behavior of the bulk and surface plasmon polaritons is investigated in detail. The dispersion and mean free path of the plasmon, the depth of the skin layer for the conducting and dielectric surfaces are calculated. The contribution of the plasmon to the optical properties is estimated from the spectral density for the Bi2Se3 and Sb2Te3 samples. Keywords: ellipsometry, plasmon, plasmonics, plasmon dispersion, plasmon mean free path, plasmon penetration depth.
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Alizade E.H. "Study of plasmon resonance in Bi-=SUB=-2-=/SUB=-Se-=SUB=-3-=/SUB=- and Sb-=SUB=-2-=/SUB=-Te-=SUB=-3-=/SUB=- by infrared spectral ellipsometry." Optics and Spectroscopy 132, no. 2 (2022): 241. http://dx.doi.org/10.21883/eos.2022.02.53685.2599-21.
Повний текст джерелаАнотація:
In the infrared region of the spectrum (IR), the optical properties of single-crystal samples of narrow-gap degenerate semiconductors Bi2Se3 and Sb2Te3 are investigated by infrared spectral ellipsometry (SE). The transport properties of the Drude fitting of dielectric functions obtained by spectroscopic ellipsometry are studied. The behavior of the bulk and surface plasmon polaritons is investigated in detail. The dispersion and mean free path of the plasmon, the depth of the skin layer for the conducting and dielectric surfaces are calculated. The contribution of the plasmon to the optical properties is estimated from the spectral density for the Bi2Se3 and Sb2Te3 samples. Keywords: ellipsometry, plasmon, plasmonics, plasmon dispersion, plasmon mean free path, plasmon penetration depth.
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Sain, Basudeb, Roy Kaner, Yaara Bondy, and Yehiam Prior. "Plasmonic flat surface Fabry-Perot interferometry." Nanophotonics 7, no. 3 (February 23, 2018): 635–41. http://dx.doi.org/10.1515/nanoph-2017-0082.
Повний текст джерелаАнотація:
AbstractWe report measurements of the optical transmission through a plasmonic flat surface interferometer. The transmission spectrum shows Fabry-Perot-like modes, where for each mode order, the maximal transmission occurs at a gap that grows linearly with wavelength, giving the appearance of diagonal dependence on gap and wavelength. The experimental results are supported by numerical solutions of the wave equations and by a simplified theoretical model that is based on the coupling between localized and propagating surface plasmon. This work explains not only the appearance of the modes but also their sharp dependence on the gap, taking into consideration the refractive indices of the surrounding media. The transmission spectra provide information about the phase difference between the light impinging on the two cavities, enabling interferometric measurement of the light phase by transmission through the coupled plasmonic cavities. The 1° phase-difference resolution is obtained without any propagation distance, thus making this interferometer suitable for on-chip operation.
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Duque, Johan, Brayan Madrigal, Henry Riascos, and Yenny Avila. "Colloidal Metal Oxide Nanoparticles Prepared by Laser Ablation Technique and Their Antibacterial Test." Colloids and Interfaces 3, no. 1 (February 4, 2019): 25. http://dx.doi.org/10.3390/colloids3010025.
Повний текст джерелаАнотація:
In this article we report the production of metal oxide (TiFe2O4, ZnFe2O4) nanoparticles by pulsed laser ablation technique in a liquid environment. We used nanosecond Nd: YAG laser systems working at 532 nm and 1064 nm of wavelength and the energy of the laser beam was kept constant at 80 mJ. Absorbance spectra, surface plasmon resonance, optical band-gap, and nanoparticle morphology were investigated using ultraviolet-visible (UV-Vis) spectroscopy, Fourier transform infrared spectroscopy (FTIR), and scanning electron microscopy (SEM). Changing the wavelength of the laser for growth, nanoparticles showed shift between the absorbance and surface plasmon resonance peaks in their UV-Vis spectra, which implies that the optical properties of the colloid nanoparticles depend on laser parameters. This was confirmed with the variation of the band gap energy. Furthermore, redshift for the absorbance peak was observed for samples as-grown at 532 nm around 150 nm as a function of time preparation. Conversely, for the samples as-grown at 1064 nm there was no shift in the absorbance spectra, which could be due to agglomeration and formation of larger particles. The characterization results showed appropriate plasmonic photo-catalysts properties of the particles, hence the photoactivation of the nanoparticles was examined on antibacterial effect using colonies of Staphylococcus aureus and Escherichia coli.
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Chou Chau, Yuan-Fong, Kuan-Hung Chen, Hai-Pang Chiang, Chee Ming Lim, Hung Ji Huang, Chih-Hsien Lai, and N. T. R. N. Kumara. "Fabrication and Characterization of a Metallic–Dielectric Nanorod Array by Nanosphere Lithography for Plasmonic Sensing Application." Nanomaterials 9, no. 12 (November 26, 2019): 1691. http://dx.doi.org/10.3390/nano9121691.
Повний текст джерелаАнотація:
In this paper, a periodic metallic–dielectric nanorod array which consists of Si nanorods coated with 30 nm Ag thin film set in a hexagonal configuration is fabricated and characterized. The fabrication procedure is performed by using nanosphere lithography with reactive ion etching, followed by Ag thin-film deposition. The mechanism of the surface and gap plasmon modes supported by the fabricated structure is numerically demonstrated by the three-dimensional finite element method. The measured and simulated absorptance spectra are observed to have a same trend and a qualitative fit. Our fabricated plasmonic sensor shows an average sensitivity of 340.0 nm/RIU when applied to a refractive index sensor ranging from 1.0 to 1.6. The proposed substrates provide a practical plasmonic nanorod-based sensing platform, and the fabrication methods used are technically effective and low-cost.
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Velez, Raymond A., Nickolay V. Lavrik, Ivan I. Kravchenko, Michael J. Sepaniak, and Marco A. De Jesus. "Surface-Enhanced Raman Scattering (SERS) Studies of Disc-on-Pillar (DOP) Arrays: Contrasting Enhancement Factor with Analytical Performance." Applied Spectroscopy 73, no. 6 (May 20, 2019): 665–77. http://dx.doi.org/10.1177/0003702819846503.
Повний текст джерелаАнотація:
The use of nanomachining methods capable of reproducible construction of nano-arrayed devices have revolutionized the field of plasmonic sensing by the introduction of a diversity of rationally engineered designs. Significant strides have been made to fabricate plasmonic platforms with tailored interparticle gaps to improve their performance for surface-enhanced Raman scattering (SERS) applications. Over time, a dichotomy has emerged in the implementation of SERS for analytical applications, the construction of substrates, optimization of interparticle spacing as a means to optimize electromagnetic field enhancement at the localized surface plasmon level, and the substrate sensitivity over extended areas to achieve quantitative performance. This work assessed the enhancement factor of plasmonic Ag/SiO2/Si disc-on-pillar (DOP) arrays of variable pitch with its analytical performance for quantitative applications. Experimental data were compared with those from finite-difference time-domain (FDTD) simulations used in the optimization of the array dimensions. A self-assembled monolayer (SAM) of benzenethiol rendered highly reproducible signals (RSD ∼4–10%) and SERS substrate enhancement factor (SSEF) values in the orders of 106–108 for all pitches. Spectra corresponding to rhodamine 6G (R6G) and 4-aminobenzoic acid demonstrated the advantages of using the more densely packed DOP arrays with a 160 nm pitch (gap = 40 nm) for quantitation in spite of the strongest SSEF was attained for a pitch of 520 nm corresponding to a 400 nm gap.
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Reyes-Gómez, E., S. B. Cavalcanti, and L. E. Oliveira. "Plasmon-polariton signature in the transmission and reflection spectra of one-dimensional metamaterial heterostructures." MRS Proceedings 1617 (2013): 187–92. http://dx.doi.org/10.1557/opl.2013.1183.
Повний текст джерелаАнотація:
ABSTRACTThe transmission and reflection properties of a meta-stack composed of a periodic AB arrangement of an air(A)/metamaterial(B) bilayer is presented, with the multi layered system embedded between two semi-infinite layers of the A material. For oblique incidence, a finite projection along the growth direction of the electric or magnetic field of the incident wave associated with the TM or TE modes, respectively, leads to a coupling of the photon modes with the bulk electric or magnetic metamaterial plasmons, in each layer of the meta-stack. This field-matter coupling gives rise to plasmon-polariton modes and signatures of electric or magnetic longitudinal bulk-plasmon polariton modes in the transmission, as well as in the reflection properties of the meta-stack, by means of a plasmon-polariton gap. Such features survive even in the case of a single bilayer and experimental observation should be, therefore, easily achieved.
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Li, Feng, Skandan Chandrasekar, Aftab Ahmed, and Anna Klinkova. "Interparticle gap geometry effects on chiroptical properties of plasmonic nanoparticle assemblies." Nanotechnology 33, no. 12 (December 28, 2021): 125203. http://dx.doi.org/10.1088/1361-6528/ac3f12.
Повний текст джерелаАнотація:
Abstract Chiral linear assemblies of plasmonic nanoparticles with chiral optical activity often show low asymmetry factors. Systematic understanding of the structure-property relationship in these systems must be improved to facilitate rational design of their chiroptical response. Here we study the effect of large area interparticle gaps in chiral linear nanoparticle assemblies on their chiroptical properties using a tetrahelix structure formed by a linear face-to-face assembly of nanoscale Au tetrahedra. Using finite-difference time-domain and finite element methods, we performed in-depth evaluation of the extinction spectra and electric field distribution in the tetrahelix structure and its dependence on various geometric parameters. The reported structure supports various plasmonic modes, one of which shows a strong incident light handedness selectivity that is associated with large face-to-face junctions. This works highlights the importance of gap engineering in chiral plasmonic assemblies to achieve g-factors greater than 1 and produce structures with a handedness-selective optical response.
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Poulin, Mathieu, Steven Giannacopoulos, and Maksim Skorobogatiy. "Surface Wave Enhanced Sensing in the Terahertz Spectral Range: Modalities, Materials, and Perspectives." Sensors 19, no. 24 (December 13, 2019): 5505. http://dx.doi.org/10.3390/s19245505.
Повний текст джерелаАнотація:
The terahertz spectral range (frequencies of 0.1–10 THz) has recently emerged as the next frontier in non-destructive imaging and sensing. Here, we review amplitude-based and phase-based sensing modalities in the context of the surface wave enhanced sensing in the terahertz frequency band. A variety of surface waves are considered including surface plasmon polaritons on metals, semiconductors, and zero gap materials, surface phonon polaritons on polaritonic materials, Zenneck waves on high-k dielectrics, as well as spoof surface plasmons and spoof Zenneck waves on structured interfaces. Special attention is paid to the trade-off between surface wave localization and sensor sensitivity. Furthermore, a detailed theoretical analysis of the surface wave optical properties as well as the sensitivity of sensors based on such waves is supplemented with many examples related to naturally occurring and artificial materials. We believe our review can be of interest to scientists pursuing research in novel high-performance sensor designs operating at frequencies beyond the visible/IR band.
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El-Molla, Sara, A. F. Mansour, and A. E. Hammad. "Enhancement of Fluorescence and Photostability Based on Interaction of Fluorescent Dyes with Silver Nanoparticles for Luminescent Solar Concentrators." Journal of Nanomaterials 2017 (2017): 1–13. http://dx.doi.org/10.1155/2017/9701251.
Повний текст джерелаАнотація:
For luminescent solar concentrators (LSCs), it is important to enhance the fluorescence quantum yield (FQY) and photostability. Our measurements have demonstrated that the addition of silver nanoparticles to dye solution causes broadening of absorption bands, so the spectral range of sunlight absorbed by LSC has increased. Silver nanoparticles (NPs) were characterized by X-ray diffraction (XRD) and UV-Vis absorption spectra. UV-Vis spectrum showed a single peak at 442 nm due to the surface plasmon resonance (SPR). The position of SPR peak exhibited a red shift after the sample was exposed to UV irradiation (unfiltered light). The optical band gap values have a reduction from 2.46 to 2.37 eV after irradiation for 960 minutes. Such reduction in optical band gap may be due to change in particle size calculated using Mie theory. The photostability of organic dyes used was improved after adding silver nanoparticles. The area under fluorescence spectra of dyes with silver NPs increased by 41–31% when compared with identical dye concentrations without silver nanoparticles as a result of interaction of the species with silver NPs.
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Lumdee, Chatdanai, Binfeng Yun, and Pieter G. Kik. "Effect of surface roughness on substrate-tuned gold nanoparticle gap plasmon resonances." Nanoscale 7, no. 9 (2015): 4250–55. http://dx.doi.org/10.1039/c4nr05893c.
Повний текст джерелаАнотація:
The impact of nanoscale surface roughness on substrate-tuned gold nanoparticle plasmon resonances is demonstrated by comparing single-particle scattering spectra with simulated scattering spectra of gold nanoparticles on gold films with realistic roughness.
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Ализаде, Э. Г. "Исследование плазмонного резонанса в Bi-=SUB=-2-=/SUB=-Se-=SUB=-3-=/SUB=- и Sb-=SUB=-2-=/SUB=-Te-=SUB=-3-=/SUB=- методом инфракрасной спектральной эллипсометрии". Оптика и спектроскопия 130, № 2 (2022): 249. http://dx.doi.org/10.21883/os.2022.02.51991.2599-21.
Повний текст джерелаАнотація:
In the infrared region of the spectrum (IR), the optical properties of single-crystal samples of narrow-gap degenerate semiconductors Bi2Se3 and Sb2Te3 are investigated by infrared spectral ellipsometry (SE). The transport properties of the Drude fitting of dielectric functions obtained by spectroscopic ellipsometry are studied. The behavior of the bulk and surface plasmon polaritons is investigated in detail. The dispersion and mean free path of the plasmon, the depth of the skin layer for the conducting and dielectric surfaces are calculated. The contribution of the plasmon to the optical properties is estimated from the spectral density for the Bi2Se3 and Sb2Te3 samples.
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Mukherjee, Ashutosh, Quan Liu, Frank Wackenhut, Fang Dai, Monika Fleischer, Pierre-Michel Adam, Alfred J. Meixner, and Marc Brecht. "Gradient SERS Substrates with Multiple Resonances for Analyte Screening: Fabrication and SERS Applications." Molecules 27, no. 16 (August 10, 2022): 5097. http://dx.doi.org/10.3390/molecules27165097.
Повний текст джерелаАнотація:
Surface-enhanced Raman spectroscopy (SERS) provides a strong enhancement to an inherently weak Raman signal, which strongly depends on the material, design, and fabrication of the substrate. Here, we present a facile method of fabricating a non-uniform SERS substrate based on an annealed thin gold (Au) film that offers multiple resonances and gap sizes within the same sample. It is not only chemically stable, but also shows reproducible trends in terms of geometry and plasmonic response. Scanning electron microscopy (SEM) reveals particle-like and island-like morphology with different gap sizes at different lateral positions of the substrate. Extinction spectra show that the plasmonic resonance of the nanoparticles/metal islands can be continuously tuned across the substrate. We observed that for the analytes 1,2-bis(4-pyridyl) ethylene (BPE) and methylene blue (MB), the maximum SERS enhancement is achieved at different lateral positions, and the shape of the extinction spectra allows for the correlation of SERS enhancement with surface morphology. Such non-uniform SERS substrates with multiple nanoparticle sizes, shapes, and interparticle distances can be used for fast screening of analytes due to the lateral variation of the resonances within the same sample.
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Abboud, M. M., E. A. Konshina, and D. P. Shcherbinin. "Hybrid Structures of a-C:H Films Covered with Ag Nanoparticles for Application in Photonics-=SUP=-*-=/SUP=-." Журнал технической физики 128, no. 8 (2020): 1195. http://dx.doi.org/10.21883/os.2020.08.49726.1024-20.
Повний текст джерелаАнотація:
n this paper, the optical density and photoluminescence (PL) spectra of thin-film hybrid structures based on amorphous hydrogenated carbon (a-C : H) with a wide (2.7 eV) and narrow (0.4 eV) optical gap covered with granulated silver films were studied. The main goal was to study the impact of nanostructures morphology and the thickness of granulated silver films on these hybrid structures spectra. Ag films of 2 nm, 4 nm, and 10 nm gravimetric thicknesses were deposited by thermal evaporation on a-C : H film surfaces previously prepared by direct current CVD. With increasing Ag film thickness, the main dipole band intensity was enhanced, and the quadrupole mode band appeared in the optical density spectra of the hybrid structures. The influence of Ag NP sizes on the quenching and enhancement of photoluminescence intensity of a-C : H films with the different optical gap was shown. Exciton-plasmon interactions in the structures with the Ag film of 10 nm thickness led to the PL intensity enhancement of the wide- and narrow-gap a-C : H films to 2 and 19 times at a wavelength of 488 nm. Nevertheless, the PL intensity of the narrow-gap film remained lower as compared to a wide-gap a-C : H film. The impact of a cross-section amplification and the Purcell effect on the PL enhancement of a-C : H in the thin-film structures as a result of localized surface plasmon resonance excitation in Ag nanoparticles are discussed. Keywords: silver nanoparticles, morphology nanostructure, amorphous hydrogenated carbon, optical density spectra, exciton-plasmon interactions, photoluminescence.
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Zhang, Nan, Lin Wu, Ping Bai, Jinghua Teng, Wolfgang Knoll, and Xiaodong Zhou. "Plasmonic Responses in Metal Nanoslit Array Fabricated by Interference Lithography." Journal of Molecular and Engineering Materials 04, no. 03 (September 2016): 1640007. http://dx.doi.org/10.1142/s2251237316400074.
Повний текст джерелаАнотація:
Gap tunable gold nanoslit arrays were fabricated by interference lithography and investigated numerically to understand the impact of fabrication errors on plasmonic responses. To fabricate the gap tunable gold nanoslit arrays, photoresist nanoslit arrays on quartz substrate were first formed by laser interference, and then converted to gold nanoslit array on glass substrate by perpendicular gold deposition and photoresist lift-off. Because the photoresist nanoslit has a sinusoidal profile due to the laser light interference lithography, different photoresist development time from 20[Formula: see text]s to 30[Formula: see text]s can tune the photoresist width from 100[Formula: see text]nm to 70[Formula: see text]nm, thus allows the gap-width-tuned metallic nanoslits to be attained accordingly. The optical properties of the fabricated gold nanoslit arrays were investigated experimentally and theoretically by studying the absorption in the transmission spectra. Within the wavelength range of 400[Formula: see text]nm to 860[Formula: see text]nm, the nanoslit in air has two prominent absorption peaks at 500[Formula: see text]nm and 670[Formula: see text]nm. It is found that a simulation model with gold nanoslit fabrication errors such as size variation, chromium adhesive layer and gold residue in nanoslit gaps considered can better match the simulation peaks with the experiments. The simulation of the gold nanoslit array in air indicates that the 500[Formula: see text]nm peak includes the interband transition and surface plasmon polariton (SPP) at air-gold surface, and the other peak at 670[Formula: see text]nm is SPP at glass side. The two SPP peaks are both sensitive to the refractive index of surrounding solution, with sensitivities of the two peaks demonstrated to be 267[Formula: see text]nm/RIU and 111[Formula: see text]nm/RIU in experiments, and 462[Formula: see text]nm/RIU and 180[Formula: see text]nm/RIU by simulation. The lower sensitivity detected by experiments might be due to some air bubbles in the flow cell reducing the effective refractive index around the nanoslit. The shorter wavelength SPP mode is 2.4 (in experiments) or 2.6 times (by simulation) more sensitive than the long wavelength SPP mode because its plasmonic field concentrates on water-gold surface. The plasmonic responses we simulated with fabrication errors explained our experimental investigations, and deepened our understanding on the application of the gold nanoslit array for refractive index-based biosensing.
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Huang, Yi, Shuncong Zhong, Tingting Shi, Yao-chun Shen, and Daxiang Cui. "Terahertz plasmonic phase-jump manipulator for liquid sensing." Nanophotonics 9, no. 9 (June 29, 2020): 3011–21. http://dx.doi.org/10.1515/nanoph-2020-0247.
Повний текст джерелаАнотація:
AbstractTerahertz (THz) plasmonic sensors has been regarded as exciting advances in biomedical engineering, due to their real-time, label-free, and ultrasensitive monitoring features. But actually, its widespread application remains impeded by poor modulation properties of operating frequency, single amplitude characterization method, and limited to low-loss substances. In the work, an ultraprecision THz sensor is achieved with direct phase readout capacity via combining steerable plasmonic resonance and attenuated total reflection. Interestingly, the oft-neglected THz phase were found to be ideal for plasmonic sensing characterization. Detailed investigation shows that the reflected THz phase exhibits two entirely different jump responses to coupling gap. Remarkably, the Q-factor of phase spectra for optimal coupling gaps, are generally higher than that of fixed coupling gaps, which falls within the range of 9.7–43.4 (4–26 times higher than its counterpart in amplitude measurements) in liquids sensing. The unique phase-jump responses on metasurfaces pave the way for novel THz sensing methods.
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Grande, Marco, Maria Antonietta Vincenti, Tiziana Stomeo, Giuseppe Valerio Bianco, Domenico de Ceglia, Giuseppe Morea, Roberto Marani, et al. "Novel Plasmonic Bio-Sensing System Based on Two-Dimensional Gold Patch Arrays for Linear and Nonlinear Regimes." Advances in Science and Technology 81 (September 2012): 15–19. http://dx.doi.org/10.4028/www.scientific.net/ast.81.15.
Повний текст джерелаАнотація:
We propose a novel bio-sensing platform based on the observation of the shift of the leaky surface plasmon mode that occurs at the edge of the plasmonic band gap of metal gratings based on two-dimensional gold nano-patch arrays when an analyte is deposited on the top of the metallic structure. We detail the numerical analysis, the fabrication and the characterization of these two-dimensional arrangements of gold patches in linear regime showing that sensitivity of our device approaches a value of 1000 nm/RIU with a corresponding Figure of Merit (FOM) of 222 RIU-1. We provide experimental proof of the sensing capabilities of the device by observing colour variations in the diffracted field when the air overlayer is replaced with a small quantity of Isopropyl Alcohol (IPA). Effects of technological tolerance such as rounded corners and surface imperfections are also discussed. We also report proof of changes in colour intensities as a function of the air/filling ratio ad periodicity and discuss how they can be obtained by diffracted spectra. Finally we report the numerical and experimental investigation of the non-linear behaviour of the device highlighting the Surface Enhanced Raman Scattering (SERS) performance.
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Vaghasiya, Tusharkumar K. "The Study of Change in Optical Properties of Highly AgNO3 Doped Poly Vinyl Alcohol Hydrosol." Nano Hybrids and Composites 12 (November 2016): 57–66. http://dx.doi.org/10.4028/www.scientific.net/nhc.12.57.
Повний текст джерелаАнотація:
Highly Ag doped PVA (20%wt., 35%wt., 40%wt.) were prepared by chemical reaction. The transmission and reflection spectra were recorded by UV-Vis-NIR spectrophotometer within the wavelength of 180nm-1200nm. The absorption has been evaluated by reflectance and transmittance spectra. Absorption coefficient, extinction coefficient, refractive index, optical conductivity and real and imaginary part of dielectric constant were calculated from optical spectra and plotted versus wavelength, it was shown that the adding of AgNO3 affect all these parameters by increasing their values. The optical band gap decreases with concentration of Ag increases. The diameter of doped silver nanoparticles has been estimated by assuming free particles behavior of conduction electron and calculated with the help of Surface Plasmon Resonance band of silver nanoparticles which is of the order of 14±0.5nm. Nearly symmetric shape and narrow FWHM of SPR band indicate that the synthesized silver nanoparticles are nearly spherical in shape. FTIR transmission spectra were recorded by single beam Fourier transform infrared spectrometer (Spectrum GX, Perkin Elmer, U.S.A.) in the spectral range of 4000 cm-1-400 cm-1. FTIR spectrum peaks correspond to molecular vibrations and chemical bonds, indicate the presence of silver in the PVA polymer structure.
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Коншина, Е. А., Д. П. Щербинин та M. M. Aboud. "Усиление фотолюминесценции и комбинационного рассеяния в гибридных тонкопленочных структурах a-C:H с наночастицами серебра". Журнал технической физики 128, № 3 (2020): 422. http://dx.doi.org/10.21883/os.2020.03.49070.314-19.
Повний текст джерелаАнотація:
n this work, we studied changes in the spectra of optical density, photoluminescence (PL) and Raman spectra of hybrid thin-film structures based on a-C: H and granular silver films before and after annealing of samples at 200 ° C. The hypsochromic shift of the main plasmon peak, the formation of double resonance spectra, and an increase in the band intensity were observed after annealing of samples with the gravimetric Ag film thickness of 10 nm. The influence of both the morphology of the nanostructure of Ag films and the features of the electronic structure of a-C: H films were observed on the plasmon enhancement of the PL and Raman spectra. For samples based on a-C:H with an optical gap Eg = 0.4 eV, a more effective PL enhancement was observed after annealing of the samples. At the same time, in the samples with Eg = 2.7 eV, the PL intensity practically did not change, remaining higher. The amplification of resonant Raman scattering was selective. It was associated with scattering by polycyclic aromatic groups predominant in the structure of the a-C: H film with a narrower optical gap.
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Mikhailova, Tatyana, Alexander Shaposhnikov, Anatoly Prokopov, Andrey Karavainikov, Sergey Tomilin, Sergey Lyashko, and Vladimir Berzhansky. "Tamm plasmon-polaritons structures with Bi-substituted garnet layers." EPJ Web of Conferences 185 (2018): 02016. http://dx.doi.org/10.1051/epjconf/201818502016.
Повний текст джерелаАнотація:
New original Tamm plasmon-polaritons (TPP) structures with Bi-substituted iron garnet and Au plasmonic layers were proposed, synthesized and investigated. The structures with single and double garnet layers were modelled to form a TPP mode at the center of photonic band gab. The top Au layer has the gradient thickness varied in the range from 0 to 65.2 nm. It was found the features of TPP resonances as a function of the thickness of metal coating. The resonances on TPP have the maximum optical quality factor and transmission at the vicinity of Au thickness of 30 nm. These configurations are optimum to form the highest intensity of electric field of light wave in the area of the magnetic layers. It was found the spectral blue and red shifts of TPP mode with increasing of Au thickness. The blue and red shifts can be explained respectively by structural and thickness changes of Au coating. The maximum resonant values of Faraday rotation were –2.1° at 664 nm and –12.3° at 645 nm for structures with single and double garnet layers, respectively, and thickness of Au coating of 65.2 nm.
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Sadeghi, Pedram, Kaiyu Wu, Tomas Rindzevicius, Anja Boisen, and Silvan Schmid. "Fabrication and characterization of Au dimer antennas on glass pillars with enhanced plasmonic response." Nanophotonics 7, no. 2 (June 30, 2017): 497–505. http://dx.doi.org/10.1515/nanoph-2017-0011.
Повний текст джерелаАнотація:
AbstractWe report on the fabrication and dark-field spectroscopy characterization of Au dimer nanoantennas placed on top of SiO2 nanopillars. The reported process enables the fabrication of nanopillar dimers with gaps down to 15 nm and heights up to 1 μm. A clear dependence of the plasmonic resonance position on the dimer gap is observed for smaller pillar heights, showing the high uniformity and reproducibility of the process. It is shown how increasing the height of nanopillars significantly affects the recorded elastic scattering spectra from Au nanoantennas. The results are compared to finite-difference time-domain (FDTD) and finite-element method (FEM) simulations. Additionally, measured spectra are accompanied by dark-field microscopy images of the dimers, showing the pronounced change in color. Placing nanoantennas on nanopillars with a height comparable to the in-plane dimer dimensions results in an enhancement of the scattering response, which can be understood through reduced interaction of the near-fields with the substrate. When increasing the pillar height further, scattering by the pillars themselves manifests itself as a strong tail at lower wavelengths. Additionally, strong directional scattering is expected as a result of the interface between the nanoantennas and nanopillars, which is taken into account in simulations. For pillars of height close to the plasmonic resonance wavelength, the scattering spectra become more complex due to additional scattering peaks as a result of larger geometrical nonuniformities.