| 1. |
- Shegai, Timur, 1982, et al.
(författare)
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A bimetallic nanoantenna for directional colour routing
- 2011
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Ingår i: Nature Communications. - : Springer Science and Business Media LLC. - 2041-1723 .- 2041-1723. ; 2:1
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Tidskriftsartikel (refereegranskat)abstract
- Recent progress in nanophotonics includes demonstrations of meta-materials displaying negative refraction at optical frequencies, directional single photon sources, plasmonic analogies of electromagnetically induced transparency and spectacular Fano resonances. The physics behind these intriguing effects is to a large extent governed by the same single parameter-optical phase. Here we describe a nanophotonic structure built from pairs of closely spaced gold and silver disks that show phase accumulation through material-dependent plasmon resonances. The bimetallic dimers show exotic optical properties, in particular scattering of red and blue light in opposite directions, in spite of being as compact as similar to lambda(3)/100. These spectral and spatial photon-sorting nanodevices can be fabricated on a wafer scale and offer a versatile platform for manipulating optical response through polarization, choice of materials and geometrical parameters, thereby opening possibilities for a wide range of practical applications.
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| 2. |
- Zengin, Gülis, 1982, et al.
(författare)
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Plasmonic nanoantennas for SERS, directional light, sensing and strong coupling
- 2013
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Ingår i: International Conference on Transparent Optical Networks. - 2162-7339. - 9781479906833
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Konferensbidrag (refereegranskat)abstract
- In this paper we discuss several examples of generating directional light emission on a nanoscale as well as utilization of these results for color routing, sensing and strong coupling applications. Examples include propagating plasmons in metallic nanowires, spontaneous formation of optical phase mismatch in materially asymmetric silver-gold and palladium-gold dimers and exciton-induced transparency in individual silver nanorods covered by a thin layer of J-aggregates. © 2013 IEEE.
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| 3. |
- Miljkovic, Vladimir, 1982, et al.
(författare)
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Mode-specific directional emission from hybridized particle-on-a-film plasmons
- 2011
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Ingår i: Optics Express. - 1094-4087. ; 19:14, s. 12856-12864
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Tidskriftsartikel (refereegranskat)abstract
- We investigate the electromagnetic interaction between a gold nanoparticle and a thin gold film on a glass substrate. The coupling between the particle plasmons and the surface plasmon polaritons of the film leads to the formation of two localized hybrid modes, one low-energy. film-like. plasmon and one high-energy plasmon dominated by the nanoparticle. We find that the two modes have completely different directional scattering patterns on the glass side of the film. The high-energy mode displays a characteristic dipole emission pattern while the low-energy mode sends out a substantial part of its radiation in directions parallel to the particle dipole moment. The relative strength of the two radiation patterns vary strongly with the distance between the particle and the film, as determined by the degree of particle-film hybridization. (C) 2011 Optical Society of America
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| 4. |
- Miljkovic, Vladimir, 1982, et al.
(författare)
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Simulating light scattering from supported plasmonic nanowires
- 2012
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Ingår i: Optics Express. - : Optical Society of America. - 1094-4087 .- 1094-4087. ; 20:10, s. 10816-10826
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Tidskriftsartikel (refereegranskat)abstract
- We present a method for calculating the differential scattering cross sections from nanostructures close to an interface separating two semi-infinitive dielectric media. The method combines a fast finite element software (Comsol multiphysics), used for calculations of the fields around and inside the structure, and the Green's functions method, which is used to find the far field distribution from the calculated total fields inside the nanostructure. We apply the method to calculations of scattering spectra from silver nanowires supported by an air-glass interface, a system that is of high current interest in relation to various nanophotonics applications. The results are analyzed in relation to analytical models and compared to experimentally measured spectra, to which we find a good agreement.
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| 5. |
- Shegai, Timur, 1982, et al.
(författare)
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Angular Distribution of Surface-Enhanced Raman Scattering from Individual Au Nanoparticle Aggregates
- 2011
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Ingår i: ACS Nano. - : American Chemical Society (ACS). - 1936-086X .- 1936-0851. ; 5:3, s. 2036-2041
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Tidskriftsartikel (refereegranskat)abstract
- Nano-optical antennas based on plasmonic metal particles are well-known for their ability to dramatically concentrate electromagnetic energy. However, not much attention has been devoted to the directionality properties of nanoantennas. Here, we report on the angular distribution of surface-enhanced Raman scattering (SERS) emitted by isolated aggregates of gold nanoparticles. We find that most of the radiation appears at angles exceeding the critical angle of the air-glass interface supporting the aggregates, and we demonstrate that angle-resolved imaging can be used as a fast and facile method for determination of the three-dimensional orientation and symmetry of the nanoantenna.
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| 6. |
- Shegai, Timur, 1982, et al.
(författare)
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Unidirectional Broadband Light Emission from Supported Plasmonic Nanowires
- 2011
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Ingår i: Nano Letters. - : American Chemical Society (ACS). - 1530-6992 .- 1530-6984. ; 11:2, s. 706-711
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Tidskriftsartikel (refereegranskat)abstract
- Metal nanowires are thought to become key elements in future nanophotonics applications. Here we show that single crystal silver nanowires supported on a dielectric interface behave similar to broadband unidirectional antennas for visible, light. The degree of directionality can be controlled through the nanowire radius and its dielectric environment and the effect can be interpreted in terms of so-called leakage radiation from surface plasmons propagating in a single direction along a wire. We measure a forward-to-backward emission ratio exceeding 15 dB and an angular spread of 4 degrees for wires with radii of the order 150 nm on glass in air. These findings could pave the way for development of metal nanowires as subwavelength directors of light in solar, sensor, and spectroscopy applications.
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| 7. |
- Edman Jönsson, Gustav, 1983, et al.
(författare)
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Nanoplasmon-enabled macroscopic thermal management
- 2014
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Ingår i: Scientific Reports. - : Springer Science and Business Media LLC. - 2045-2322 .- 2045-2322. ; 4, s. 5111-
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Tidskriftsartikel (refereegranskat)abstract
- In numerous applications of energy harvesting via transformation of light into heat the focus recently shifted towards highly absorptive nanoplasmonic materials. It is currently established that noble metals-based absorptive plasmonic platforms deliver significant light-capturing capability and can be viewed as super-absorbers of optical radiation. Naturally, approaches to the direct experimental probing of macroscopic temperature increase resulting from these absorbers are welcomed. Here we derive a general quantitative method of characterizing heat-generating properties of optically absorptive layers via macroscopic thermal imaging. We further monitor macroscopic areas that are homogeneously heated by several degrees with nanostructures that occupy a mere 8% of the surface, leaving it essentially transparent and evidencing significant heat generation capability of nanoplasmon-enabled light capture. This has a direct bearing to a large number of applications where thermal management is crucial.
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| 8. |
- Edman Jönsson, Gustav, 1983, et al.
(författare)
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Solar Transparent Radiators by Optical Nanoantennas
- 2017
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Ingår i: Nano Letters. - : American Chemical Society (ACS). - 1530-6984 .- 1530-6992. ; 17:11, s. 6766-6772
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Tidskriftsartikel (refereegranskat)abstract
- Architectural windows are a major cause of thermal discomfort as the inner glazing during cold days can be several degrees colder than the indoor air. Mitigating this, the indoor temperature has to be increased, leading to unavoidable thermal losses. Here we present solar thermal surfaces based on complex nanoplasmonic antennas that can raise the temperature of window glazing by up to 8 K upon solar irradiation while transmitting light with a color rendering index of 98.76. The nanoantennas are directional, can be tuned to absorb in different spectral ranges, and possess a structural integrity that is not substrate-dependent, and thus they open up for application on a broad range of surfaces.
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| 9. |
- El Daif, O., et al.
(författare)
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Silver nanodiscs for light scattering in thin epitaxial silicon solar cells: Influence of the disc radius
- 2011
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Ingår i: Materials Research Society Symposium Proceedings. - : Springer Science and Business Media LLC. - 0272-9172. - 9781627482110 ; 1391, s. 75-80
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Konferensbidrag (refereegranskat)abstract
- The effect of silver nanoparticles showing localised plasmonic resonances on the efficiency of thin film silicon solar cells is studied. Silver (Ag) nanodiscs were deposited on the surface of silicon cells grown on highly doped silicon substrates, through hole-mask colloidal lithography, which is a low-cost and bottom-up technique. The cells have no back reflector in order to exclusively study the effect of the front surface on their properties. Cells with nanoparticles were compared with both bare silicon cells and cells with an antireflection coating. We optically observe a resonance showing an absorption increase controllable by the disc radius. We also see an increase in efficiency with respect to bare cells, but we see a decrease in efficiency with respect to cells with an antireflection coating due to losses at wavelengths below the plasmon resonance. As the material properties are not notably affected by the particles deposition, the loss mechanism is an important absorption in the nanoparticles. We confirm this by numerical simulations.
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| 10. |
- Jain, S., et al.
(författare)
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Broadband absorption enhancement in ultra-thin crystalline Si solar cells by incorporating metallic and dielectric nanostructures in the back reflector
- 2015
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Ingår i: Progress in Photovoltaics: Research and Applications. - : Wiley. - 1099-159X .- 1062-7995. ; 23:9, s. 1144-1156
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Tidskriftsartikel (refereegranskat)abstract
- We propose a back reflecting scheme in order to enhance the maximum achievable current in one micron thick crystalline silicon solar cells. We perform 3D numerical investigations of the scattering properties of metallic nanostructures located at the back side and optimize them for enhancing absorption in the silicon layer. We validate our numerical results experimentally and also compare the absorption enhancement in the solar cell structure, both with quasi-periodic and random metallic nanostructures. We have looked at the interplay between the metallic nanostructures and an integrated back reflector. We show that the combination of metallic nanoparticles and a metallic reflector results in significant parasitic absorption. We compared this to another implementation based on titanium dioxide nanoparticles, which act as a Lambertian reflector of light. Our simulation and experimental results show that this proposed configuration results in reduced absorption losses and in broadband enhancement of absorption for ultra-thin solar cells, paving the way to an optimal back reflector for thin film photovoltaics.
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