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Gürdal E, Horneber A, Meixner AJ, Kern DP, Zhang D, Fleischer M. Enhancement of the second harmonic signal of nonlinear crystals by a single metal nanoantenna. NANOSCALE 2020; 12:23105-23115. [PMID: 33180087 DOI: 10.1039/d0nr05696k] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
This work fundamentally investigates how the second harmonic generation (SHG) from commercial nonlinear crystals can be boosted by the addition of individual optical nanoantennas. Frequency conversion plays an important role in modern non-linear optics, and nonlinear crystals have become a widely used building block for non-linear processes. Still, SHG remains hampered by limited conversion efficiency. To strengthen SHG from the crystal surface, we investigate the interaction of LiNbO3 crystals with individual gold nanodiscs. The scattered intensities and resonance frequencies of the nanodiscs are analyzed by dark-field spectroscopy and simulations. Subsequently, the discs on LiNbO3 are excited by a pulsed femtosecond laser in a parabolic mirror setup. Comparing the SHG at the position of a single nanodisc at resonance on the crystal with that of the unstructured crystal and of gold nanodiscs on a reference substrate, local SHG enhancement of up to a factor of three was achieved in the focal volume through the presence of the antenna.
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Affiliation(s)
- Emre Gürdal
- Institute for Applied Physics, Eberhard Karls University of Tübingen, Auf der Morgenstelle 10, 72076 Tübingen, Germany.
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2
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Cunha J, Guo TL, Alabastri A, Proietti Zaccaria R. Tuning temperature gradients in subwavelength plasmonic nanocones with tilted illumination. OPTICS LETTERS 2020; 45:5472-5475. [PMID: 33001922 DOI: 10.1364/ol.404950] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/07/2020] [Accepted: 08/28/2020] [Indexed: 06/11/2023]
Abstract
Inducing and controlling temperature gradients in illuminated subwavelength plasmonic structures is a challenging task. Here, we present a strategy to remotely induce and tune temperature gradients in a subwavelength metallic nanocone by adjusting the angle of incidence of linearly polarized continuous-wave illumination. We demonstrate, through rigorous three-dimensional numerical simulations, that properly tilting the incident illumination angle can increase or decrease the photoinduced temperature gradients within the nanostructure. We analyze the apex-base photoinduced temperature gradient for different illumination directions, resembling typical illumination schemes utilized in surface or tip-enhanced Raman spectroscopy.
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Schäfer C, Perera PN, Laible F, Olynick DL, Schwartzberg AM, Weber-Bargioni A, Cabrini S, Schuck PJ, Kern DP, Fleischer M. Selectively accessing the hotspots of optical nanoantennas by self-aligned dry laser ablation. NANOSCALE 2020; 12:19170-19177. [PMID: 32926034 DOI: 10.1039/d0nr04024j] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Plasmonic nanostructures serve as optical antennas for concentrating the energy of incoming light in localized hotspots close to their surface. By positioning nanoemitters in the antenna hotspots, energy transfer is enabled, leading to novel hybrid antenna-emitter-systems, where the antenna can be used to manipulate the optical properties of the nano-objects. The challenge remains how to precisely position emitters within the hotspots. We report a self-aligned process based on dry laser ablation of a calixarene that enables the attachment of molecules within the electromagnetic hotspots at the tips of gold nanocones. Within the laser focus, the ablation threshold is exceeded in nanoscale volumes, leading to selective access of the hotspot areas. A first indication of the site-selective functionalization process is given by attaching fluorescently labelled proteins to the nanocones. In a second example, Raman-active molecules are selectively attached only to nanocones that were previously exposed in the laser focus, which is verified by surface enhanced Raman spectroscopy. Enabling selective functionalization is an important prerequisite e.g. for preparing single photon sources for quantum optical technologies, or multiplexed Raman sensing platforms.
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Affiliation(s)
- Christian Schäfer
- Institute for Applied Physics and Center LISA+, Eberhard Karls Universität Tübingen, Auf der Morgenstelle 10, 72076 Tübingen, Germany.
| | - Pradeep N Perera
- The Molecular Foundry, Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Building 67, Berkeley, CA 94720, USA
| | - Florian Laible
- Institute for Applied Physics and Center LISA+, Eberhard Karls Universität Tübingen, Auf der Morgenstelle 10, 72076 Tübingen, Germany.
| | - Deirdre L Olynick
- The Molecular Foundry, Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Building 67, Berkeley, CA 94720, USA
| | - Adam M Schwartzberg
- The Molecular Foundry, Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Building 67, Berkeley, CA 94720, USA
| | - Alexander Weber-Bargioni
- The Molecular Foundry, Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Building 67, Berkeley, CA 94720, USA
| | - Stefano Cabrini
- The Molecular Foundry, Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Building 67, Berkeley, CA 94720, USA
| | - P James Schuck
- The Molecular Foundry, Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Building 67, Berkeley, CA 94720, USA
| | - Dieter P Kern
- Institute for Applied Physics and Center LISA+, Eberhard Karls Universität Tübingen, Auf der Morgenstelle 10, 72076 Tübingen, Germany.
| | - Monika Fleischer
- Institute for Applied Physics and Center LISA+, Eberhard Karls Universität Tübingen, Auf der Morgenstelle 10, 72076 Tübingen, Germany.
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Zhu S, Eldeeb MA, Pang SW. 3D nanoplasmonic biosensor for detection of filopodia in cells. LAB ON A CHIP 2020; 20:2188-2196. [PMID: 32421116 DOI: 10.1039/d0lc00173b] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Filopodia are thin finger-like protrusions from cells and they are hard to detect using electrical, mechanical, or optical sensors because of their nanometer scale features. Besides, the signals from filopodia and the cell membrane are often mixed together which makes the detection of filopodia challenging. Here, a 3D nanoplasmonic biosensor with microposts is proposed to overcome these limitations. By using suitable chemical coating and physical dimensions, the signals from filopodia and the cell membrane were separated by having the microposts keep the cell membrane from making contact with the nanoplasmonic biosensor. The filopodia were detected by the 3D asymmetrical nanopillars with sharp Fano resonance. The sensitivity and figure of merit of the nanoplasmonic biosensor were 650 nm per refractive index unit and 28.3, respectively. A large peak shift of 6 nm was observed for the detection of MC3T3 osteoblastic cell filopodia at a concentration of 1300 cells per mm2. To the best of our knowledge, this is the first demonstration of filopodia detection using nanoplasmonic biosensors, where microposts were used to separate the cell membrane from filopodia and the 3D nanoplasmonic biosensors were used to monitor filopodia on the nanometer scale. These combined 3D micro- and nano-structures allow filopodia to be detected using different sensors without interference from the cell membrane.
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Affiliation(s)
- Shuyan Zhu
- Department of Electrical Engineering, City University of Hong Kong, Kowloon, Hong Kong.
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Dreser C, Gürdal E, Bautista G, Horneber A, Zang X, Gollmer DA, Meixner AJ, Kern DP, Zhang D, Kauranen M, Fleischer M. Second harmonic generation enhancement by polarization-matched nanostructures -INVITED. EPJ WEB OF CONFERENCES 2020. [DOI: 10.1051/epjconf/202023805001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
Frequency conversion plays an important role in both fundamental and applied nano-optics. Doubling the frequency of light by second harmonic generation (SHG) is a vital process e.g. in laser optics or high-resolution microscopy. SHG can be created through symmetry breaking at plasmonic nanostructures, or the local high electric near-fields of plasmonic nanoantennas can be utilized to further enhance the SHG e.g. from nonlinear crystals. Examples of SHG microscopy using cylindrical vector beams in combination with tilted nanocones and radially symmetric oligomers are shown as well as enhancement studies of the SHG from nonlinear crystals decorated with polarization-matched nanostructures.
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Wang J, Butet J, Bernasconi GD, Baudrion AL, Lévêque G, Horrer A, Horneber A, Martin OJF, Meixner AJ, Fleischer M, Adam PM, Zhang D. Strong second-harmonic generation from Au-Al heterodimers. NANOSCALE 2019; 11:23475-23481. [PMID: 31799534 DOI: 10.1039/c9nr07644a] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Second-harmonic generation (SHG) is investigated from three kinds of lithographically fabricated plasmonic systems: Al monomers, Au monomers and Au-Al heterodimers with nanogaps of 20 nm. Spectrally integrated SHG intensities and the linear optical responses are recorded and compared. The results show that for the monomer nanoantennas, the SHG signal depends sensitively on the linear excitation of the plasmon resonance by the fundamental wavelength. For Au-Al heterodimer nanoantennas, apart from fundamental resonant excitation, nonlinear optical factors such as SH driving fields and phase interferences need to be taken into account, which play significant roles at the excitation and scattering stages of SHG radiation. It is interesting to note that a possible energy transfer process could take place between the two constituting nanoparticles (NPs) in the Au-Al heterodimers. Excited at the linear plasmon resonance, the Au NP transfers the absorbed energy from the fundamental field to the nearby Al NP, which efficiently scatters SHG to the far-field, giving rise to an enhanced SHG intensity. The mechanisms reported here provide new approaches to boost the far-field SHG radiation by taking full advantage of strongly coupled plasmonic oscillations and the synergism from materials of different compositions.
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Affiliation(s)
- Jiyong Wang
- Institute of Physical and Theoretical Chemistry, Eberhard Karls University of Tübingen, Auf der Morgenstelle 15, 72076 Tübingen, Germany. and Light, Nanomaterials and Nanotechnology, University of Technology of Troyes, 12 Rue Marie Curie, CS42060, 10004 Troyes Cedex, France. and Center for Light-Matter-Interaction, Sensors and Analytics (LISA+), Eberhard Karls University of Tübingen, Auf der Morgenstelle 15, 72076 Tübingen, Germany and Key Laboratory of 3D Micro/Nano Fabrication and Characterization of Zhejiang Province, School of Engineering, Westlake University, 18 Shilongshan Road, 310024 Hangzhou, Zhejiang Province, China and Key Laboratory of 3D Micro/Nano Fabrication and Characterization of Zhejiang Province, School of Engineering, Westlake Institute for Advanced Study, 18 Shilongshan Road, 310024 Hangzhou, Zhejiang Province, China
| | - Jérémy Butet
- Nanophotonics and Metrology Laboratory (NAM), Swiss Federal Institute of Technology, Lausanne (EPFL), 1015 Lausanne, Switzerland
| | - Gabriel David Bernasconi
- Nanophotonics and Metrology Laboratory (NAM), Swiss Federal Institute of Technology, Lausanne (EPFL), 1015 Lausanne, Switzerland
| | - Anne-Laure Baudrion
- Light, Nanomaterials and Nanotechnology, University of Technology of Troyes, 12 Rue Marie Curie, CS42060, 10004 Troyes Cedex, France.
| | - Gaëtan Lévêque
- Institut d'Electronique, de Microélectronique et de Nanotechnologie (IEMN, CNRS-8520), Cité Scientifique, Avenue Poincaré, 59652 Villeneuve d'Ascq, France
| | - Andreas Horrer
- Light, Nanomaterials and Nanotechnology, University of Technology of Troyes, 12 Rue Marie Curie, CS42060, 10004 Troyes Cedex, France. and Institute for Applied Physics, Eberhard Karls University of Tübingen, Auf der Morgenstelle 10, 72076 Tübingen, Germany
| | - Anke Horneber
- Institute of Physical and Theoretical Chemistry, Eberhard Karls University of Tübingen, Auf der Morgenstelle 15, 72076 Tübingen, Germany. and Center for Light-Matter-Interaction, Sensors and Analytics (LISA+), Eberhard Karls University of Tübingen, Auf der Morgenstelle 15, 72076 Tübingen, Germany
| | - Olivier J F Martin
- Nanophotonics and Metrology Laboratory (NAM), Swiss Federal Institute of Technology, Lausanne (EPFL), 1015 Lausanne, Switzerland
| | - Alfred J Meixner
- Institute of Physical and Theoretical Chemistry, Eberhard Karls University of Tübingen, Auf der Morgenstelle 15, 72076 Tübingen, Germany. and Center for Light-Matter-Interaction, Sensors and Analytics (LISA+), Eberhard Karls University of Tübingen, Auf der Morgenstelle 15, 72076 Tübingen, Germany
| | - Monika Fleischer
- Center for Light-Matter-Interaction, Sensors and Analytics (LISA+), Eberhard Karls University of Tübingen, Auf der Morgenstelle 15, 72076 Tübingen, Germany and Institute for Applied Physics, Eberhard Karls University of Tübingen, Auf der Morgenstelle 10, 72076 Tübingen, Germany
| | - Pierre-Michel Adam
- Light, Nanomaterials and Nanotechnology, University of Technology of Troyes, 12 Rue Marie Curie, CS42060, 10004 Troyes Cedex, France.
| | - Dai Zhang
- Institute of Physical and Theoretical Chemistry, Eberhard Karls University of Tübingen, Auf der Morgenstelle 15, 72076 Tübingen, Germany. and Center for Light-Matter-Interaction, Sensors and Analytics (LISA+), Eberhard Karls University of Tübingen, Auf der Morgenstelle 15, 72076 Tübingen, Germany
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Fulmes J, Schäfer C, Kern DP, Adam PM, Fleischer M. Relative spectral tuning of the vertical versus base modes in plasmonic nanocones. NANOTECHNOLOGY 2019; 30:415201. [PMID: 31339108 DOI: 10.1088/1361-6528/ab2d5c] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Gold nanocones acting as optical antennas offer an excellent geometry for focusing light near the cone tip, acting as nano-light sources with spot sizes on the order of the tip radius. However only the vertical plasmon mode oscillating in the axial direction can effectively excite the tip, whereas lateral modes oscillating along the cone base create mostly unwanted background in applications. The present work investigates the three-dimensional plasmonic mode structure of nanocones both experimentally and numerically. By tuning the nanocone aspect ratio, the modes can be spectrally tuned relative to each other, making them coincide for maximum excitation, or tuning the base mode away from the vertical mode for effective background suppression.
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Affiliation(s)
- Julia Fulmes
- Institute for Applied Physics and Center LISA+, Eberhard Karls Universität Tübingen, Auf der Morgenstelle 10 and 15, 72076 Tübingen, Germany
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