| 1. |
- Andrén, Daniel, 1991, et al.
(författare)
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Large-Scale Metasurfaces Made by an Exposed Resist
- 2020
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Ingår i: ACS Photonics. - : American Chemical Society (ACS). - 2330-4022. ; 7:4, s. 885-892
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Tidskriftsartikel (refereegranskat)abstract
- Phase-gradient metasurfaces have the potential to revolutionize photonics by offering ultrathin alternatives to a wide range of common optical elements, including bulky refractive optics, waveplates, and axicons. However, the fabrication of state-of-the-art metasurfaces typically involves several expensive, time-consuming, and potentially hazardous processing steps. To address this limitation, a facile methodology to construct phase-gradient metasurfaces from an exposed standard electron beam resist is developed. The method dramatically cuts the required processing time and cost as well as reduces safety hazards. The advantages of the method are demonstrated by constructing high-performance flat optics based on the Pancharatnam-Berry phase gradient concept for the entire visible wavelength range. Manufactured devices include macroscopic (1 cm diameter) positive lenses, gratings exhibiting anomalous reflection, and cylindrical metalenses on flexible plastic substrates.
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| 2. |
- Andrén, Daniel, 1991, et al.
(författare)
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Metasurfaces for Divergent Beams and Large-Area Metasurfaces
- 2021
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Ingår i: International Conference on Metamaterials, Photonic Crystals and Plasmonics. - 2429-1390. ; , s. 517-518
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Konferensbidrag (refereegranskat)abstract
- We will give an overview of our recent work on the design and fabrication of metasurfaces, i.e., dense arrays of subwavelength-sized scatterers (meta-atoms) designed in shape, size, position, and orientation. First, we have developed simulation strategies for large-scale metasurfaces and metasurfaces for strongly divergent beams. Second, we have developed a facile fabrication technique based on an exposed resist to build large-scale metasurfaces. These novel computational and fabrication techniques allow us to achieve metasurfaces with unprecedented functionality.
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| 3. |
- Baranov, Denis, 1990, et al.
(författare)
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Anapole-Enhanced Intrinsic Raman Scattering from Silicon Nanodisks
- 2018
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Ingår i: ACS Photonics. - : American Chemical Society (ACS). - 2330-4022. ; 5:7, s. 2730-2736
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Tidskriftsartikel (refereegranskat)abstract
- Enhancement of inelastic light emission processes through resonant excitation usually correlates with enhanced scattering of the excitation light, as is for example typically the case for surface-enhanced fluorescence and Raman scattering from plasmonic nanostructures. Here, we demonstrate an unusual case where a reverse correlation is instead observed, that is, we measure a multifold enhancement of Raman emission along with suppressed elastic scattering. The system enabling this peculiar effect is composed of silicon nanodisks excited in the so-called anapole state, for which electric and toroidal dipoles interfere destructively in the far-field, thereby preventing elastic scattering, while the optical fields in the core of the silicon particles are enhanced, thus, amplifying light-matter interaction and Raman scattering at the Stokes-shifted emission wavelength. Our results demonstrate an unusual relation between resonances in elastic and inelastic scattering from nanostructures and suggest a route toward background-free frequency conversion devices.
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| 4. |
- Cuadra, Jorge, 1982, et al.
(författare)
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Hybrid dielectric waveguide spectroscopy of individual plasmonic nanoparticles
- 2017
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Ingår i: AIP Advances. - : AIP Publishing. - 2158-3226 .- 2158-3226. ; 7:7, s. Article no: 075207 -
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Tidskriftsartikel (refereegranskat)abstract
- Plasmonics is a mature scientific discipline which is now entering the realm of practical applications. Recently, significant attention has been devoted to on-chip hybrid devices where plasmonic nanoantennas are integrated in standard Si 3 N 4 photonic waveguides. Light in these systems is usually coupled at the waveguide apexes by using multiple objectives and/or tapered optical fibers, rendering the analysis of spectroscopic signals a complicated task. Here, we show how by using a grating coupler and a low NA objective, quantitative spectroscopic information similar to standard dark-field spectroscopy can be obtained at the single-nanoparticle level. This technology may be useful for enabling single-nanoparticle studies in non-linear excitation regimes and/or in complex experimental environments, thus enriching the toolbox of nanophotonic methods.
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| 5. |
- Cuadra, Jorge, 1982, et al.
(författare)
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Observation of Tunable Charged Exciton Polaritons in Hybrid Monolayer WS 2 -Plasmonic Nanoantenna System
- 2018
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Ingår i: Nano Letters. - : American Chemical Society (ACS). - 1530-6992 .- 1530-6984. ; 18:3, s. 1777-1785
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Tidskriftsartikel (refereegranskat)abstract
- © 2018 American Chemical Society. Formation of dressed light-matter states in optical structures, manifested as Rabi splitting of the eigen energies of a coupled system, is one of the key effects in quantum optics. In pursuing this regime with semiconductors, light is usually made to interact with excitons, electrically neutral quasiparticles of semiconductors; meanwhile interactions with charged three-particle states, trions, have received little attention. Here, we report on strong interaction between localized surface plasmons in silver nanoprisms and excitons and trions in monolayer tungsten disulfide (WS 2 ). We show that the plasmon-exciton interactions in this system can be efficiently tuned by controlling the charged versus neutral exciton contribution to the coupling process. In particular, we show that a stable trion state emerges and couples efficiently to the plasmon resonance at low temperature by forming three bright intermixed plasmon-exciton-trion polariton states. Our findings open up a possibility to exploit electrically charged polaritons at the single nanoparticle level.
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| 6. |
- Karpinski, Pawel, 1985, et al.
(författare)
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Optical Rotation and Thermometry of Laser Tweezed Silicon Nanorods
- 2020
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Ingår i: Nano Letters. - : American Chemical Society (ACS). - 1530-6992 .- 1530-6984. ; 20:9, s. 6494-6501
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Tidskriftsartikel (refereegranskat)abstract
- Optical rotation of laser tweezed nanoparticles offers a convenient means for optical to mechanical force transduction and sensing at the nanoscale. Plasmonic nanoparticles are the benchmark system for such studies, but their rapid rotation comes at the price of high photoinduced heating due to Ohmic losses. We show that Mie resonant silicon nanorods with characteristic dimensions of ∼220 × 120 nm2 can be optically trapped and rotated at frequencies up to 2 kHz in water using circularly polarized laser light. The temperature excess due to heating from the trapping laser was estimated by phonon Raman scattering and particle rotation analysis. We find that the silicon nanorods exhibit slightly improved thermal characteristics compared to Au nanorods with similar rotation performance and optical resonance anisotropy. Altogether, the results indicate that silicon nanoparticles have the potential to become the system of choice for a wide range of optomechanical applications at the nanoscale.
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| 7. |
- Martinez Llinas, Jade, 1985, et al.
(författare)
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A Gaussian reflective metasurface for advanced wavefront manipulation
- 2019
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Ingår i: Optics Express. - 1094-4087 .- 1094-4087. ; 27:15, s. 21069-21082
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Tidskriftsartikel (refereegranskat)abstract
- Metasurfaces enable us to control the fundamental properties of light with unprecedented flexibility. However, most metasurfaces realized to date aim at modifying plane waves. While the manipulation of nonplanar wavefronts is encountered in a diverse number of applications, their control using metasurfaces is still in its infancy. Here we design a metareflector able to reflect a diverging Gaussian beam back onto itself with efficiency over 90% and focusing at an arbitrary distance. We outline a clear route towards the design of complex metareflectors that can find applications as diverse as optical tweezing, lasing, and quantum optics.
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| 8. |
- Martinez Llinas, Jade, 1985, et al.
(författare)
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Computational modelling of metasurfaces for strongly divergent beams
- 2019
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Ingår i: Optics InfoBase Conference Papers. - 2162-2701. ; Part F143-EQEC 2019
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Konferensbidrag (refereegranskat)abstract
- The control of light by means of metasurfaces with subwavelength building blocks has been explored in the last few years, giving rise to unprecedented functionalities [1,2]. Thin flat lenses and other optical components have been obtained by engineering the building blocks of metasurfaces. However, most metasurfaces realized so far are essentially designed to modify plane waves [3-5]. While the manipulation of nonplanar wave fronts is encountered in a diverse variety of applications, their control using metasurfaces is still in its infancy. Here we showcase the computational tools to design metasurfaces that can also manipulate strongly divergent light beams.
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| 9. |
- Verre, Ruggero, 1985, et al.
(författare)
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Metasurfaces and Colloidal Suspensions Composed of 3D Chiral Si Nanoresonators
- 2017
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Ingår i: Advanced Materials. - : Wiley. - 0935-9648 .- 1521-4095. ; 29:29
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Tidskriftsartikel (refereegranskat)abstract
- High-refractive-index silicon nanoresonators are promising low-loss alternatives to plasmonic particles in CMOS-compatible nanophotonics applications. However, complex 3D particle morphologies are challenging to realize in practice, thus limiting the range of achievable optical functionalities. Using 3D film structuring and a novel gradient mask transfer technique, the first intrinsically chiral dielectric metasurface is fabricated in the form of a monolayer of twisted silicon nanocrescents that can be easily detached and dissolved into colloidal suspension. The metasurfaces exhibit selective handedness and a circular dichroism as large as 160 degrees mu m(-1) due to pronounced differences in induced current loops for left-handed and right-handed polarization. The detailed morphology of the detached particles is analyzed using high-resolution transmission electron microscopy. Furthermore, it is shown that the particles can be manipulated in solution using optical tweezers. The fabrication and detachment method can be extended to different nanoparticle geometries and paves the way for a wide range of novel nanophotonic experiments and applications of high-index dielectrics.
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| 10. |
- Wersäll, Martin, 1985, et al.
(författare)
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Directional Nanoplasmonic Antennas for Self-Referenced Refractometric Molecular Analysis
- 2014
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Ingår i: Journal of Physical Chemistry C. - : American Chemical Society (ACS). - 1932-7447 .- 1932-7455. ; 118:36, s. 21075-21080
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Tidskriftsartikel (refereegranskat)abstract
- Localized surface-plasmon resonance (LSPR) sensors are typically based on tracing resonance peak shifts that precisely follow changes in the local refractive index. Such measurements usually require a spectrometer, a stable light source, and an accurate LSPR position tracing technique. As a simple but efficient alternative, we investigated a self-referenced single-wavelength sensing scheme based on angle-dependent and highly directional radiation patterns originating from a monolayer of asymmetric gold nanodimers. We found that one could easily trace a model biotinneutravidin recognition reaction as well as minute bulk refractive index changes, by measuring the intensity ratio between the light scattered in two different directions with respect to the dimers. The refractometric resolution of the methodology was estimated to be on the order of Delta n approximate to 10(-5) RIU. These results may be particularly useful for label-free biosensing applications that require a combination of simple and cost-effective optical readout with a reasonable sensitivity.
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