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Matson J, Wasserroth S, Ni X, Obst M, Diaz-Granados K, Carini G, Renzi EM, Galiffi E, Folland TG, Eng LM, Michael Klopf J, Mastel S, Armster S, Gambin V, Wolf M, Kehr SC, Alù A, Paarmann A, Caldwell JD. Controlling the propagation asymmetry of hyperbolic shear polaritons in beta-gallium oxide. Nat Commun 2023; 14:5240. [PMID: 37640711 PMCID: PMC10462611 DOI: 10.1038/s41467-023-40789-7] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2023] [Accepted: 08/07/2023] [Indexed: 08/31/2023] Open
Abstract
Structural anisotropy in crystals is crucial for controlling light propagation, particularly in the infrared spectral regime where optical frequencies overlap with crystalline lattice resonances, enabling light-matter coupled quasiparticles called phonon polaritons (PhPs). Exploring PhPs in anisotropic materials like hBN and MoO3 has led to advancements in light confinement and manipulation. In a recent study, PhPs in the monoclinic crystal β-Ga2O3 (bGO) were shown to exhibit strongly asymmetric propagation with a frequency dispersive optical axis. Here, using scanning near-field optical microscopy (s-SNOM), we directly image the symmetry-broken propagation of hyperbolic shear polaritons in bGO. Further, we demonstrate the control and enhancement of shear-induced propagation asymmetry by varying the incident laser orientation and polariton momentum using different sizes of nano-antennas. Finally, we observe significant rotation of the hyperbola axis by changing the frequency of incident light. Our findings lay the groundwork for the widespread utilization and implementation of polaritons in low-symmetry crystals.
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Affiliation(s)
| | - Sören Wasserroth
- Fritz Haber Institute of the Max Planck Society, Berlin, Germany
| | - Xiang Ni
- School of Physics, Central South University, Changsha, Hunan, China
- Photonics Initiative, Advanced Science Research Center, City University of New York, New York, NY, USA
| | - Maximilian Obst
- Institute of Applied Physics, TUD Dresden University of Technology, Dresden, Germany
| | | | - Giulia Carini
- Fritz Haber Institute of the Max Planck Society, Berlin, Germany
| | - Enrico Maria Renzi
- Photonics Initiative, Advanced Science Research Center, City University of New York, New York, NY, USA
- Physics Program, Graduate Center, City University of New York, New York, NY, USA
| | - Emanuele Galiffi
- Photonics Initiative, Advanced Science Research Center, City University of New York, New York, NY, USA
| | | | - Lukas M Eng
- Institute of Applied Physics, TUD Dresden University of Technology, Dresden, Germany
| | | | | | - Sean Armster
- NG NEXT, Northrop Grumman Corporation, Redondo Beach, CA, USA
| | - Vincent Gambin
- NG NEXT, Northrop Grumman Corporation, Redondo Beach, CA, USA
| | - Martin Wolf
- Fritz Haber Institute of the Max Planck Society, Berlin, Germany
| | - Susanne C Kehr
- Institute of Applied Physics, TUD Dresden University of Technology, Dresden, Germany
| | - Andrea Alù
- Photonics Initiative, Advanced Science Research Center, City University of New York, New York, NY, USA
- Physics Program, Graduate Center, City University of New York, New York, NY, USA
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Ni X, Carini G, Ma W, Renzi EM, Galiffi E, Wasserroth S, Wolf M, Li P, Paarmann A, Alù A. Observation of directional leaky polaritons at anisotropic crystal interfaces. Nat Commun 2023; 14:2845. [PMID: 37202412 DOI: 10.1038/s41467-023-38326-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2023] [Accepted: 04/26/2023] [Indexed: 05/20/2023] Open
Abstract
Extreme anisotropy in some polaritonic materials enables light propagation with a hyperbolic dispersion, leading to enhanced light-matter interactions and directional transport. However, these features are typically associated with large momenta that make them sensitive to loss and poorly accessible from far-field, being bound to the material interface or volume-confined in thin films. Here, we demonstrate a new form of directional polaritons, leaky in nature and featuring lenticular dispersion contours that are neither elliptical nor hyperbolic. We show that these interface modes are strongly hybridized with propagating bulk states, sustaining directional, long-range, sub-diffractive propagation at the interface. We observe these features using polariton spectroscopy, far-field probing and near-field imaging, revealing their peculiar dispersion, and - despite their leaky nature - long modal lifetime. Our leaky polaritons (LPs) nontrivially merge sub-diffractive polaritonics with diffractive photonics onto a unified platform, unveiling opportunities that stem from the interplay of extreme anisotropic responses and radiation leakage.
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Affiliation(s)
- Xiang Ni
- Photonics Initiative, Advanced Science Research Center, City University of New York, New York, NY, 10031, USA
- School of Physics and Electronics, Central South University, Changsha, Hunan, 410083, China
| | - Giulia Carini
- Fritz Haber Institute of the Max Planck Society, Berlin, Germany
| | - Weiliang Ma
- School of Optical and Electronic Information, Wuhan National Laboratory for Optoelectronics and Wuhan National high Magnetic Field Center, Huazhong University of Science and Technology, Wuhan, China
| | - Enrico Maria Renzi
- Photonics Initiative, Advanced Science Research Center, City University of New York, New York, NY, 10031, USA
| | - Emanuele Galiffi
- Photonics Initiative, Advanced Science Research Center, City University of New York, New York, NY, 10031, USA
| | - Sören Wasserroth
- Fritz Haber Institute of the Max Planck Society, Berlin, Germany
| | - Martin Wolf
- Fritz Haber Institute of the Max Planck Society, Berlin, Germany
| | - Peining Li
- School of Optical and Electronic Information, Wuhan National Laboratory for Optoelectronics and Wuhan National high Magnetic Field Center, Huazhong University of Science and Technology, Wuhan, China.
- Optics Valley Laboratory, Hubei, 430074, China.
| | | | - Andrea Alù
- Photonics Initiative, Advanced Science Research Center, City University of New York, New York, NY, 10031, USA.
- Physics Program, Graduate Center, City University of New York, New York, NY, 10016, USA.
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Abstract
Moiré patterns are additional, long-range periodicities in twisted crystalline bilayers. They are known to fundamentally change the electronic states of the layers, but similar effects on their mechanical and vibrational properties have not been discussed so far. Here we show that the moiré potential shifts the radial breathing mode in double-walled carbon nanotubes (DWCNTs). The change in frequency is expected to be proportional to the shift in optical transition energies, which are induced by the moiré patterns. To verify our model, we performed resonance Raman scattering on purified and sorted semiconducting DWCNTs. We find that the radial breathing mode shifts up to 14 cm-1 higher in energy followed by displacement of optical transition energies of up to 200 meV to lower energies, in comparison to the single-walled tubes. We show how to identify the strong coupling condition in DWCNTs from their phonon frequencies and construct a Kataura plot to aid their future experimental assignment.
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Affiliation(s)
- Georgy Gordeev
- Department of Physics, Freie Universität Berlin, Arnimallee 14, 14195 Berlin, Germany
| | - Sören Wasserroth
- Department of Physics, Freie Universität Berlin, Arnimallee 14, 14195 Berlin, Germany
- Fritz-Haber-Institut der Max-Planck-Gesellschaft, Faradayweg 4-6, 14195 Berlin, Germany
| | - Han Li
- Institute of Nanotechnology, Karlsruhe Institute of Technology, Karlsruhe, Germany
| | - Benjamin Flavel
- Institute of Nanotechnology, Karlsruhe Institute of Technology, Karlsruhe, Germany
| | - Stephanie Reich
- Department of Physics, Freie Universität Berlin, Arnimallee 14, 14195 Berlin, Germany
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Wasserroth S, Heeg S, Mueller NS, Kusch P, Hübner U, Gaufrès E, Tang NYW, Martel R, Vijayaraghavan A, Reich S. Resonant, Plasmonic Raman Enhancement of α-6T Molecules Encapsulated in Carbon Nanotubes. J Phys Chem C Nanomater Interfaces 2019; 123:10578-10585. [PMID: 32064011 PMCID: PMC7011763 DOI: 10.1021/acs.jpcc.9b01600] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/19/2019] [Revised: 04/01/2019] [Indexed: 05/17/2023]
Abstract
Surface-enhanced Raman scattering (SERS) and resonant Raman scattering are widely used techniques to enhance the Raman intensity of molecules and nanomaterials by several orders of magnitude. In SERS, typically, molecules are investigated and their intrinsic resonance is often ignored while discussing the plasmonic enhancement. Here, we study α-sexithiophenes encapsulated in carbon nanotubes placed in the center of a nanodimer. By dielectrophoretic deposition, we place the nanotubes precisely in the center of a plasmonic gold nanodimer and observe SERS enhancement from individual tube bundles. The encapsulated molecules are not subjected to chemical enhancement because of the protective character of the nanotube. Polarization-dependent Raman measurements confirm the alignment of the molecules within the carbon nanotubes (CNTs) and reveal the influence of the plasmonic near field on the molecule's Raman intensity. We investigate the encapsulated molecules in small CNT bundles with and without plasmonic enhancement and determine the molecular and plasmonic resonance by tuning the excitation wavelength. We observe a strong red shift of the maximum Raman intensity under plasmonic enhancement toward the plasmon resonance.
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Affiliation(s)
- Sören Wasserroth
- Institut
für Experimentalphysik, Freie Universität
Berlin, Berlin 14195, Germany
| | - Sebastian Heeg
- School
of Materials, The University of Manchester, Manchester M13 9PL, U.K.
- Photonics
Laboratory, ETH Zürich, Zürich 8093, Switzerland
| | - Niclas S. Mueller
- Institut
für Experimentalphysik, Freie Universität
Berlin, Berlin 14195, Germany
| | - Patryk Kusch
- School
of Materials, The University of Manchester, Manchester M13 9PL, U.K.
| | - Uwe Hübner
- Leibniz
Institute of Photonics Technology, Jena 07745, Germany
| | - Etienne Gaufrès
- Regroupement
Québécois sur les matériaux de pointe and Département
de Chimie, Université de Montréal, Montréal, Québec H3C 3J7, Canada
| | - Nathalie Y.-W. Tang
- Regroupement
Québécois sur les matériaux de pointe and Département
de Chimie, Université de Montréal, Montréal, Québec H3C 3J7, Canada
| | - Richard Martel
- Regroupement
Québécois sur les matériaux de pointe and Département
de Chimie, Université de Montréal, Montréal, Québec H3C 3J7, Canada
| | | | - Stephanie Reich
- Institut
für Experimentalphysik, Freie Universität
Berlin, Berlin 14195, Germany
- E-mail:
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Li H, Gordeev G, Wasserroth S, Chakravadhanula VSK, Neelakandhan SKC, Hennrich F, Jorio A, Reich S, Krupke R, Flavel BS. Inner- and outer-wall sorting of double-walled carbon nanotubes. Nat Nanotechnol 2017; 12:1176-1182. [PMID: 28967894 DOI: 10.1038/nnano.2017.207] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/03/2017] [Accepted: 09/05/2017] [Indexed: 06/07/2023]
Abstract
Double-walled carbon nanotubes (DWCNTs) consist of two coaxially aligned single-walled carbon nanotubes (SWCNTs), and previous sorting methods only achieved outer-wall electronic-type selectivity. Here, a separation technique capable of sorting DWCNTs by semiconducting (S) or metallic (M) inner- and outer-wall electronic type is presented. Electronic coupling between the inner and outer wall is used to alter the surfactant coating around each of the DWCNT types, and aqueous gel permeation is used to separate them. Aqueous methods are used to remove SWCNT species from the raw material and prepare enriched DWCNT fractions. The enriched DWCNT fractions are then transferred into either chlorobenzene or toluene using the copolymer PFO-BPy to yield the four inner@outer combinations of M@M, M@S, S@M and S@S. The high purity of the resulting fractions is verified by absorption measurements, transmission electron microscopy, atomic force microscopy, resonance Raman mapping and high-density field-effect transistor devices.
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Affiliation(s)
- Han Li
- Institute of Nanotechnology, Karlsruhe Institute of Technology, 76021 Karlsruhe, Germany
| | - Georgy Gordeev
- Department of Physics, Freie Universität Berlin, 14195 Berlin, Germany
| | - Sören Wasserroth
- Department of Physics, Freie Universität Berlin, 14195 Berlin, Germany
| | - Venkata Sai Kiran Chakravadhanula
- Institute of Nanotechnology, Karlsruhe Institute of Technology, 76021 Karlsruhe, Germany
- Helmholtz Institute Ulm Electrochemical Energy Storage, 89081 Ulm, Germany
| | - Shyam Kumar Chethala Neelakandhan
- Institute of Nanotechnology, Karlsruhe Institute of Technology, 76021 Karlsruhe, Germany
- Institute of Materials Science, Technische Universität Darmstadt, 64287 Darmstadt, Germany
| | - Frank Hennrich
- Institute of Nanotechnology, Karlsruhe Institute of Technology, 76021 Karlsruhe, Germany
| | - Ado Jorio
- Department of Physics, Federal University of Minas Gerais, Belo Horizonte, Brazil
| | - Stephanie Reich
- Department of Physics, Freie Universität Berlin, 14195 Berlin, Germany
| | - Ralph Krupke
- Institute of Nanotechnology, Karlsruhe Institute of Technology, 76021 Karlsruhe, Germany
- Institute of Materials Science, Technische Universität Darmstadt, 64287 Darmstadt, Germany
| | - Benjamin Scott Flavel
- Institute of Nanotechnology, Karlsruhe Institute of Technology, 76021 Karlsruhe, Germany
- Institute of Materials Science, Technische Universität Darmstadt, 64287 Darmstadt, Germany
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