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Thomaschewski M, Prämassing M, Schill HJ, Zenin VA, Bozhevolnyi SI, Sorger VJ, Linden S. Near-Field Observation of the Photonic Spin Hall Effect. NANO LETTERS 2023; 23:11447-11452. [PMID: 37982385 DOI: 10.1021/acs.nanolett.3c02829] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/21/2023]
Abstract
The photonic spin Hall effect, referring to the spatial separation of photons with opposite spins due to spin-orbit interactions, has enabled potential for various spin-sensitive applications and devices. Here, using scattering-type near-field scanning optical microscopy, we observe spin-orbit interactions introduced by a subwavelength semiring antenna integrated in a plasmonic circuit. Clear evidence of unidirectional excitation of surface plasmon polaritons is obtained by direct comparison of the amplitude- and phase-resolved near-field maps of the plasmonic nanocircuit under excitation with photons of opposite spin states coupled to a plasmonic nanoantenna. We present details of the antenna design and experimental methods to investigate the spatial variation of complex electromagnetic fields in a spin-sensitive plasmonic circuit. The reported findings offer valuable insights into the generation, characterization, and application of the photonic spin Hall effect in photonic integrated circuits for future and emerging spin-selective nanophotonic systems.
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Affiliation(s)
- Martin Thomaschewski
- Department of Electrical & Computer Engineering, The George Washington University, 800 22nd Street NW 5000 Science & Engineering Hall, Washington, D.C. 20052, United States
| | - Mike Prämassing
- Physikalisches Institut, Universität Bonn, Nussallee 12, 53115 Bonn, Germany
| | - Hans-Joachim Schill
- Physikalisches Institut, Universität Bonn, Nussallee 12, 53115 Bonn, Germany
| | - Vladimir A Zenin
- Center for Nano Optics, University of Southern Denmark, DK-5230 Odense M, Denmark
| | - Sergey I Bozhevolnyi
- Center for Nano Optics, University of Southern Denmark, DK-5230 Odense M, Denmark
| | - Volker J Sorger
- Department of Electrical & Computer Engineering, The George Washington University, 800 22nd Street NW 5000 Science & Engineering Hall, Washington, D.C. 20052, United States
- Florida Semiconductor Institute, University of Florida, Gainesville, Florida 32603, United States
- Department of Electrical and Computer Engineering, University of Florida, Gainesville, Florida 32603, United States
| | - Stefan Linden
- Physikalisches Institut, Universität Bonn, Nussallee 12, 53115 Bonn, Germany
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2
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Yu SY, Shih MH, Ku YC, Kuo YH, Liaw JW. Water-Immersion Laser-Scanning Annealing for Improving Polycrystalline Au Films. ACS OMEGA 2022; 7:42272-42282. [PMID: 36440141 PMCID: PMC9686192 DOI: 10.1021/acsomega.2c05101] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/09/2022] [Accepted: 10/20/2022] [Indexed: 06/16/2023]
Abstract
A water-immersion laser-scanning annealing (WILSA) method was developed for the heat treatment of a deposited polycrystalline Au film on a glass. The material characterization using X-ray diffraction, field-emission scanning electron microscopy, and electron backscatter diffraction shows improved crystallinity with a more uniform crystallographic orientation of (111) and the grain growth of the annealed Au film. Additionally, the optical constants of the Au film before and after annealing were characterized by spectroscopic ellipsometry in the visible to near-infrared (NIR) regime, and the corresponding optical densities (ODs) were measured by transmittance spectroscopy. Our results show that the extinction coefficient and the OD of the annealed film are significantly reduced, particularly in the NIR regime. This is because the grain growth caused by the annealing reduces the density of grain boundaries, leading to the decrease of the loss of free electrons' scattering at grain boundaries. Hence, the damping effect of the surface plasmon is reduced. Additionally, the integrity of the WILSA-treated thin film is kept intact without pinholes, usually produced by the conventional thermal annealing. Based on the improved optical property of the WILSA-treated Au film, two performances of an insulator-metal-insulator (IMI) layered structure of biosensors are theoretically analyzed. Numerical results show that the propagation length of a long-range surface plasmon polariton along an IMI structure with an annealed Au film is significantly increased, compared to an unannealed film, particular in the NIR region. For the other application of using an IMI sensor to detect the shift of the surface-plasmon-resonance dip in the total internal reflection spectrum for the measurement of a change of the medium's refractive index, the sensitivity is also profoundly improved by the WILSA method. It is worth mentioning that the optimal heating conditions (laser wavelength, fluence, exposure time, and scanning step) depend on the thickness of the Au film. Our study provides a postprocess of WILSA to improve the optical properties of a deposited polycrystalline Au film for raising the sensitivity of the related biosensors.
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Affiliation(s)
- Shang-Yang Yu
- Department
of Mechanical Engineering, Chang Gung University, 259 Wen-Hwa 1st Rd., Taoyuan 333323, Taiwan
| | - Min-Hsiung Shih
- Research
Center for Applied Sciences, Academia Sinica, 128 Academia Road, Sec. 2,Taipei 115201, Taiwan
| | - Yun-Cheng Ku
- Institute
of Applied Mechanics, National Taiwan University, 1, Sec. 4, Roosevelt Rd., Taipei 106, Taiwan
| | - Yi-Han Kuo
- Department
of Mechanical Engineering, Chang Gung University, 259 Wen-Hwa 1st Rd., Taoyuan 333323, Taiwan
| | - Jiunn-Woei Liaw
- Department
of Mechanical Engineering, Chang Gung University, 259 Wen-Hwa 1st Rd., Taoyuan 333323, Taiwan
- Department
of Mechanical Engineering, Ming Chi University
of Technology, 84 Gungjuan
Rd., New Taipei 243303, Taiwan
- Proton
and Radiation Therapy Center, Linkou Chang
Gung Memorial Hospital, 15 Wen-Hwa 1st Rd., Taoyuan 333011, Taiwan
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3
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Lebsir Y, Boroviks S, Thomaschewski M, Bozhevolnyi SI, Zenin VA. Ultimate Limit for Optical Losses in Gold, Revealed by Quantitative Near-Field Microscopy. NANO LETTERS 2022; 22:5759-5764. [PMID: 35787133 DOI: 10.1021/acs.nanolett.2c01059] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
We report thorough measurements of surface plasmon polaritons (SPPs) running along nearly perfect air-gold interfaces formed by atomically flat surfaces of chemically synthesized gold monocrystals. By means of amplitude- and phase-resolved near-field microscopy, we obtain their propagation length and effective mode index at visible wavelengths (532, 594, 632.8, 729, and 800 nm). The measured values are compared with the values obtained from the dielectric functions of gold that are reported in literature. Importantly, a reported dielectric function of monocrystalline gold implies ∼1.5 times shorter propagation lengths than those observed in our experiments, whereas a dielectric function reported for properly fabricated polycrystalline gold leads to SPP propagation lengths matching our results. We argue that the SPP propagation lengths measured in our experiments signify the ultimate limit of optical losses in gold, encouraging further comprehensive characterization of optical material properties of pure gold as well as other plasmonic materials.
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Affiliation(s)
- Yonas Lebsir
- Centre for Nano Optics, University of Southern Denmark, 5230 Odense, Denmark
- Institute for Experimental and Applied Physics, Kiel University, 24118 Kiel, Germany
| | - Sergejs Boroviks
- Centre for Nano Optics, University of Southern Denmark, 5230 Odense, Denmark
- Nanophotonics and Metrology Laboratory (NAM), Swiss Federal Institute of Technology in Lausanne (EPFL), 1015 Lausanne, Switzerland
| | | | - Sergey I Bozhevolnyi
- Centre for Nano Optics, University of Southern Denmark, 5230 Odense, Denmark
- Danish Institute for Advanced Study, University of Southern Denmark, 5230 Odense, Denmark
| | - Vladimir A Zenin
- Centre for Nano Optics, University of Southern Denmark, 5230 Odense, Denmark
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4
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Design, Analysis, and Optimization of a Plasmonic Slot Waveguide for Mid-Infrared Gas Sensing. NANOMATERIALS 2022; 12:nano12101732. [PMID: 35630954 PMCID: PMC9144950 DOI: 10.3390/nano12101732] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/21/2022] [Revised: 05/12/2022] [Accepted: 05/16/2022] [Indexed: 02/04/2023]
Abstract
In this work, we investigated the optimization of a plasmonic slot waveguide (PSWG) in the mid-IR region particularly for a representative wavelength of 4.26 µm, which is the absorption line of CO2 and thus particularly relevant for applications. We analysed the mode features associated with metal-dielectric-metal (MDM), dielectric-metal-dielectric (DMD), and truncated metal film (TMF) structures with respect to the considered PSWG. Subsequently, the mode features of the PSWG were considered based on what we outlined for MDM, DMD, and TMF structures. Furthermore, as confinement factor and propagation length are two crucial parameters for absorption sensing applications, we optimized the PSWG based on a figure of merit (FOM) defined as the product of the aforementioned quantities. To characterize the propagation length, the imaginary part of the effective mode index of a guided mode was considered, leading to a dimensionless FOM. Finally, we investigated the PSWG also for other wavelengths and identified particularly attractive wavelengths and geometries maximizing the FOM.
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Casses LN, Kaltenecker KJ, Xiao S, Wubs M, Stenger N. Quantitative near-field characterization of surface plasmon polaritons on monocrystalline gold platelets. OPTICS EXPRESS 2022; 30:11181-11191. [PMID: 35473067 DOI: 10.1364/oe.454740] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/26/2022] [Accepted: 03/10/2022] [Indexed: 06/14/2023]
Abstract
Near-field microscopy allows for visualization of both the amplitude and phase of surface plasmon polaritons (SPPs). However, their quantitative characterization in a reflection configuration is challenging due to complex wave patterns arising from the interference between several excitation channels. Here, we present near-field measurements of SPPs on large monocrystalline gold platelets in the visible. We study systematically the influence of the incident angle of the exciting light on the SPPs launched by an atomic force microscope tip. We find that the amplitude and phase signals of these SPPs are best disentangled from other signals at grazing incident angle relative to the edge of the gold platelet. Furthermore, we introduce a simple model to extract the wavelength and in particular the propagation length of the tip-launched plasmons. Our experimental results are in excellent agreement with our theoretical model. The presented method allows the quantitative analysis of polaritons occurring in different materials at visible wavelengths.
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Heindl MB, Kirkwood N, Lauster T, Lang JA, Retsch M, Mulvaney P, Herink G. Ultrafast imaging of terahertz electric waveforms using quantum dots. LIGHT, SCIENCE & APPLICATIONS 2022; 11:5. [PMID: 34974517 PMCID: PMC8720308 DOI: 10.1038/s41377-021-00693-5] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/23/2021] [Revised: 11/26/2021] [Accepted: 12/01/2021] [Indexed: 06/02/2023]
Abstract
Microscopic electric fields govern the majority of elementary excitations in condensed matter and drive electronics at frequencies approaching the Terahertz (THz) regime. However, only few imaging schemes are able to resolve sub-wavelength fields in the THz range, such as scanning-probe techniques, electro-optic sampling, and ultrafast electron microscopy. Still, intrinsic constraints on sample geometry, acquisition speed and field strength limit their applicability. Here, we harness the quantum-confined Stark-effect to encode ultrafast electric near-fields into colloidal quantum dot luminescence. Our approach, termed Quantum-probe Field Microscopy (QFIM), combines far-field imaging of visible photons with phase-resolved sampling of electric waveforms. By capturing ultrafast movies, we spatio-temporally resolve a Terahertz resonance inside a bowtie antenna and unveil the propagation of a Terahertz waveguide excitation deeply in the sub-wavelength regime. The demonstrated QFIM approach is compatible with strong-field excitation and sub-micrometer resolution-introducing a direct route towards ultrafast field imaging of complex nanodevices in-operando.
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Affiliation(s)
- Moritz B Heindl
- Experimental Physics VIII - Ultrafast Dynamics, University of Bayreuth, Bayreuth, Germany
| | - Nicholas Kirkwood
- ARC Centre of Excellence in Exciton Science, School of Chemistry, University of Melbourne, Melbourne, Australia
| | - Tobias Lauster
- Physical Chemistry I, University of Bayreuth, Bayreuth, Germany
| | - Julia A Lang
- Experimental Physics VIII - Ultrafast Dynamics, University of Bayreuth, Bayreuth, Germany
| | - Markus Retsch
- Physical Chemistry I, University of Bayreuth, Bayreuth, Germany
| | - Paul Mulvaney
- ARC Centre of Excellence in Exciton Science, School of Chemistry, University of Melbourne, Melbourne, Australia
| | - Georg Herink
- Experimental Physics VIII - Ultrafast Dynamics, University of Bayreuth, Bayreuth, Germany.
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7
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Messner A, Jud PA, Winiger J, Eppenberger M, Chelladurai D, Heni W, Baeuerle B, Koch U, Ma P, Haffner C, Xu H, Elder DL, Dalton LR, Smajic J, Leuthold J. Broadband Metallic Fiber-to-Chip Couplers and a Low-Complexity Integrated Plasmonic Platform. NANO LETTERS 2021; 21:4539-4545. [PMID: 34006114 PMCID: PMC8193629 DOI: 10.1021/acs.nanolett.0c05069] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/24/2020] [Revised: 04/22/2021] [Indexed: 06/12/2023]
Abstract
We present a plasmonic platform featuring efficient, broadband metallic fiber-to-chip couplers that directly interface plasmonic slot waveguides, such as compact and high-speed electro-optic modulators. The metallic gratings exhibit an experimental fiber-to-slot coupling efficiency of -2.7 dB with -1.4 dB in simulations with the same coupling principle. Further, they offer a huge spectral window with a 3 dB passband of 350 nm. The technology relies on a vertically arranged layer stack, metal-insulator-metal waveguides, and fiber-to-slot couplers and is formed in only one lithography step with a minimum feature size of 250 nm. As an application example, we fabricate new modulator devices with an electro-optic organic material in the slot waveguide and reach 50 and 100 Gbit/s data modulation in the O- and C-bands within the same device. The devices' broad spectral bandwidth and their relaxed fabrication may render them suitable for experiments and applications in the scope of sensing, nonlinear optics, or telecommunications.
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Affiliation(s)
- Andreas Messner
- ETH
Zurich, Institute of Electromagnetic
Fields (IEF), 8092 Zürich, Switzerland
| | - Pascal A. Jud
- ETH
Zurich, Institute of Electromagnetic
Fields (IEF), 8092 Zürich, Switzerland
| | - Joel Winiger
- ETH
Zurich, Institute of Electromagnetic
Fields (IEF), 8092 Zürich, Switzerland
| | - Marco Eppenberger
- ETH
Zurich, Institute of Electromagnetic
Fields (IEF), 8092 Zürich, Switzerland
| | - Daniel Chelladurai
- ETH
Zurich, Institute of Electromagnetic
Fields (IEF), 8092 Zürich, Switzerland
| | - Wolfgang Heni
- Polariton
Technologies AG, 8803 Rüschlikon, Switzerland
| | | | - Ueli Koch
- ETH
Zurich, Institute of Electromagnetic
Fields (IEF), 8092 Zürich, Switzerland
| | - Ping Ma
- ETH
Zurich, Institute of Electromagnetic
Fields (IEF), 8092 Zürich, Switzerland
| | - Christian Haffner
- ETH
Zurich, Institute of Electromagnetic
Fields (IEF), 8092 Zürich, Switzerland
| | - Huajun Xu
- University
of Washington, Department of Chemistry, Seattle, Washington 98195-1700, United States
| | - Delwin L. Elder
- University
of Washington, Department of Chemistry, Seattle, Washington 98195-1700, United States
| | - Larry R. Dalton
- University
of Washington, Department of Chemistry, Seattle, Washington 98195-1700, United States
| | - Jasmin Smajic
- ETH
Zurich, Institute of Electromagnetic
Fields (IEF), 8092 Zürich, Switzerland
| | - Juerg Leuthold
- ETH
Zurich, Institute of Electromagnetic
Fields (IEF), 8092 Zürich, Switzerland
- Polariton
Technologies AG, 8803 Rüschlikon, Switzerland
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8
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Designing Mid-Infrared Gold-Based Plasmonic Slot Waveguides for CO 2-Sensing Applications. SENSORS 2021; 21:s21082669. [PMID: 33920116 PMCID: PMC8070310 DOI: 10.3390/s21082669] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/24/2021] [Revised: 04/01/2021] [Accepted: 04/08/2021] [Indexed: 11/18/2022]
Abstract
Plasmonic slot waveguides have attracted much attention due to the possibility of high light confinement, although they suffer from relatively high propagation loss originating from the presence of a metal. Although the tightly confined light in a small gap leads to a high confinement factor, which is crucial for sensing applications, the use of plasmonic guiding at the same time results in a low propagation length. Therefore, the consideration of a trade-off between the confinement factor and the propagation length is essential to optimize the waveguide geometries. Using silicon nitride as a platform as one of the most common material systems, we have investigated free-standing and asymmetric gold-based plasmonic slot waveguides designed for sensing applications. A new figure of merit (FOM) is introduced to optimize the waveguide geometries for a wavelength of 4.26 µm corresponding to the absorption peak of CO2, aiming at the enhancement of the confinement factor and propagation length simultaneously. For the free-standing structure, the achieved FOM is 274.6 corresponding to approximately 42% and 868 µm for confinement factor and propagation length, respectively. The FOM for the asymmetric structure shows a value of 70.1 which corresponds to 36% and 264 µm for confinement factor and propagation length, respectively.
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9
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Kejík L, Horák M, Šikola T, Křápek V. Structural and optical properties of monocrystalline and polycrystalline gold plasmonic nanorods. OPTICS EXPRESS 2020; 28:34960-34972. [PMID: 33182953 DOI: 10.1364/oe.409428] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/04/2020] [Accepted: 10/01/2020] [Indexed: 06/11/2023]
Abstract
The quality of lithographically prepared structures is intimately related to the properties of the metal film from which they are fabricated. Here we compare two kinds of thin gold films on a silicon nitride membrane: a conventional polycrystalline thin film deposited by magnetron sputtering and monocrystalline gold microplates that were chemically synthesised directly on the membrane's surface for the first time. Both pristine metals were used to fabricate plasmonic nanorods using focused ion beam lithography. The structural and optical properties of the nanorods were characterized by analytical transmission electron microscopy including electron energy loss spectroscopy. The dimensions of the nanorods in both substrates reproduced well the designed size of 240×80 nm2 with the deviations up to 20 nm in both length and width. The shape reproducibility was considerably improved among monocrystalline nanorods fabricated from the same microplate. Interestingly, monocrystalline nanorods featured inclined boundaries while the boundaries of the polycrystalline nanorods were upright. Q factors and peak loss probabilities of the modes in both structures are within the experimental uncertainty identical. We demonstrate that the optical response of the plasmonic nanorods is not deteriorated when the polycrystalline metal is used instead of the monocrystalline metal.
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10
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Mancini A, Gubbin CR, Berté R, Martini F, Politi A, Cortés E, Li Y, De Liberato S, Maier SA. Near-Field Spectroscopy of Cylindrical Phonon-Polariton Antennas. ACS NANO 2020; 14:8508-8517. [PMID: 32530605 DOI: 10.1021/acsnano.0c02784] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Surface phonon polaritons (SPhPs) are hybrid light-matter states in which light strongly couples to lattice vibrations inside the Reststrahlen band of polar dielectrics at mid-infrared frequencies. Antennas supporting localized surface phonon polaritons (LSPhPs) easily outperform their plasmonic counterparts operating in the visible or near-infrared in terms of field enhancement and confinement thanks to the inherently slower phonon-phonon scattering processes governing SPhP decay. In particular, LSPhP antennas have attracted considerable interest for thermal management at the nanoscale, where the emission strongly diverts from the usual far-field blackbody radiation due to the presence of evanescent waves at the surface. However, far-field measurements cannot shed light on the behavior of antennas in the near-field region. To overcome this limitation, we employ scattering-scanning near-field optical microscopy (sSNOM) to unveil the spectral near-field response of 3C-SiC antenna arrays. We present a detailed description of the behavior of the antenna resonances by comparing far-field and near-field spectra and demonstrate the existence of a mode with no net dipole moment, absent in the far-field spectra, but of importance for applications that exploit the heightened electromagnetic near fields. Furthermore, we investigate the perturbation in the antenna response induced by the presence of the AFM tip, which can be further extended toward situations where for example strong IR emitters couple to LSPhP modes.
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Affiliation(s)
- Andrea Mancini
- Chair in Hybrid Nanosystems, Nanoinstitute Munich, Faculty of Physics, Ludwig-Maxilimians-Universität München, 80539 München, Germany
| | - Christopher R Gubbin
- School of Physics and Astronomy, University of Southampton, Southampton, SO17 1BJ, United Kingdom
| | - Rodrigo Berté
- Chair in Hybrid Nanosystems, Nanoinstitute Munich, Faculty of Physics, Ludwig-Maxilimians-Universität München, 80539 München, Germany
| | - Francesco Martini
- School of Physics and Astronomy, University of Southampton, Southampton, SO17 1BJ, United Kingdom
- Istituto di Fotonica e Nanotecnologie-CNR, Via Cineto Romano 42, 00156 Roma, Italy
| | - Alberto Politi
- School of Physics and Astronomy, University of Southampton, Southampton, SO17 1BJ, United Kingdom
| | - Emiliano Cortés
- Chair in Hybrid Nanosystems, Nanoinstitute Munich, Faculty of Physics, Ludwig-Maxilimians-Universität München, 80539 München, Germany
| | - Yi Li
- School of Microelectronics, MOE Engineering Research Center of Integrated Circuits for Next Generation Communications, Southern University of Science and Technology, Shenzhen 518055, China
| | - Simone De Liberato
- School of Physics and Astronomy, University of Southampton, Southampton, SO17 1BJ, United Kingdom
| | - Stefan A Maier
- Chair in Hybrid Nanosystems, Nanoinstitute Munich, Faculty of Physics, Ludwig-Maxilimians-Universität München, 80539 München, Germany
- Department of Physics, Imperial College London, London SW7 2AZ, United Kingdom
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