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Choudhary S, Iqbal S, Karimi M, Reshef O, Alam MZ, Boyd RW. Strongly Coupled Plasmon Polaritons in Gold and Epsilon-Near-Zero Bifilms. ACS PHOTONICS 2023; 10:162-169. [PMID: 36691428 PMCID: PMC9853859 DOI: 10.1021/acsphotonics.2c01412] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 09/07/2022] [Indexed: 06/17/2023]
Abstract
Epsilon-near-zero (ENZ) polaritons in a thin transparent conducting-oxide film exhibit a significant electric field enhancement and localization within the film at frequencies close to their plasma frequency, but do not propagate. Meanwhile, plasmon polariton modes in thin metallic films can propagate for several microns, but are more loosely confined in the metal. Here, we propose a strongly coupled bilayered structure of a thin gold film on a thin indium tin oxide (ITO) film that supports hybrid polariton modes. We experimentally characterize the dispersion of these modes and show that they have propagation lengths of 4-8 μm while retaining mode confinement greater than that of the polariton in gold films by nearly an order of magnitude. We study the tunability of this coupling strength by varying the thickness of the ITO film and show that ultrastrong coupling is possible at certain thicknesses. The unusual linear and nonlinear optical properties of ITO at ENZ frequencies make these bifilms useful for the active tuning of strong coupling, ultrafast switching, and enhanced nonlinear interactions at near-infrared frequencies.
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Affiliation(s)
- Saumya Choudhary
- Institute
of Optics, University of Rochester, Rochester, New York14627, United States
| | - Saleem Iqbal
- Institute
of Optics, University of Rochester, Rochester, New York14627, United States
| | - Mohammad Karimi
- Department
of Physics, University of Ottawa, Ottawa, OntarioK1N 6N5, Canada
| | - Orad Reshef
- Department
of Physics, University of Ottawa, Ottawa, OntarioK1N 6N5, Canada
| | - M. Zahirul Alam
- Department
of Physics, University of Ottawa, Ottawa, OntarioK1N 6N5, Canada
| | - Robert W. Boyd
- Institute
of Optics, University of Rochester, Rochester, New York14627, United States
- Department
of Physics, University of Ottawa, Ottawa, OntarioK1N 6N5, Canada
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Sha Y, Xie ZT, Wu J, Fu HY, Li Q. All-optical switching in epsilon-near-zero asymmetric directional coupler. Sci Rep 2022; 12:17958. [PMID: 36289304 PMCID: PMC9606007 DOI: 10.1038/s41598-022-22573-7] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2022] [Accepted: 10/17/2022] [Indexed: 11/30/2022] Open
Abstract
We propose an all-optical switch based on an asymmetric directional coupler structure with epsilon-near-zero (ENZ) layer. The nonlinear optical properties the of ENZ layer are analyzed by hot-electron dynamics process, and the all-optical operating performance of the switch on the silicon nitride platform is investigated. It is found that the pump-induced refractive index change in ENZ layer gives rise to a transfer of signal light in the optical system. We demonstrate that the proposed switch design features an insertion loss of < 2.7 dB, low crosstalk of < - 18.93 dB, and sub-pico-second response time at the communication wavelength of 1.55 μm. With ultrafast response, high performance, and simple structure, the device provides new possibilities for all-optical communication and signal processing.
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Affiliation(s)
- Yanhua Sha
- School of Electronic and Computer Engineering, Peking University, Shenzhen, 518055, China
| | - Ze Tao Xie
- School of Electronic and Computer Engineering, Peking University, Shenzhen, 518055, China
| | - Jiaye Wu
- École Polytechnique Fédérale de Lausanne (EPFL), STI-IEM, 1015, Lausanne, Switzerland
| | - H Y Fu
- Tsinghua Shenzhen International Graduate School, Tsinghua University, Shenzhen, 518055, China
| | - Qian Li
- School of Electronic and Computer Engineering, Peking University, Shenzhen, 518055, China.
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Della Sala F. Orbital-Free Methods for Plasmonics: Linear Response. J Chem Phys 2022; 157:104101. [DOI: 10.1063/5.0100797] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Plasmonic systems, such as metal nanoparticles, are widely used in different application areas, going from biology to photovoltaics.The modeling of the optical response of such systems is of fundamental importance to analyze their behavior and to design new systems with required properties.When the characteristic sizes/distances reach a few nanometers, non-local and spill-out effects become relevant and conventional classical electrodynamics models are no more appropriate. Methods based on the Time-Dependent Density-Functional Theory (TD-DFT) represent the current reference for the description of quantum effects. However, TD-DFT is based on knowledge of all occupied orbitals whose calculation is computationally prohibitive to model large plasmonic systems of interest for applications.On the other hand, methods based on the Orbital-Free (OF) formulation of TD-DFT, can scale linearly with the system size.In this Review, OF methods ranging from semiclassical models to the quantum hydrodynamic theory, will be derived from the linear response TD-DFT, so that the key approximations and properties of each method can be clearly highlighted. The accuracy of the various approximations will be then validated for the linear optical properties of jellium nanoparticles, the most relevant model system in plasmonics. OF methods can describe the collective excitations in plasmonic systems with great accuracy andwithout system-tuned parameters. The accuracy on these methods depends only on the accuracy on the (universal) kinetic energy functional of the ground-state electronic density. Current approximations and future development directions will be indicated.
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Affiliation(s)
- Fabio Della Sala
- CNR-IMM, IMM CNR Lecce, Italy
- Istituto Italiano di Tecnologia Center for Biomolecular Nanotechnologies
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Uskov AV, Khurgin JB, Smetanin IV, Protsenko IE, Nikonorov NV. Landau Damping in Hybrid Plasmonics. J Phys Chem Lett 2022; 13:997-1001. [PMID: 35060736 DOI: 10.1021/acs.jpclett.1c04031] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
The Landau damping (LD) mechanism of the localized surface plasmon (LSP) decay is studied for the hybrid nanoplasmonic (metal core/dielectric shell) structures. It is shown that LD in hybrid structures is strongly affected by the permittivity and the electron effective mass in the dielectric shell in accordance with previous observations by Kreibig, and the strength of LD can be enhanced by an order of magnitude for some combinations of permittivity and effective mass. The physical reason for this effect is identified as an electron spillover into the dielectric where the electric field is higher than that in the metal and the presence of quasi-discrete energy levels in the dielectric. The theory indicates that the transition absorption at the metal-dielectric interface is a dominant contribution to LD in such hybrid structures. Thus, by judicious selection of dielectric material and its thickness, one can engineer decay rates and hot carrier production for important applications, such as photodetection and photochemistry.
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Affiliation(s)
- Alexander V Uskov
- P. N. Lebedev Physical Institute, Russian Academy of Sciences, Leninskiy Pr. 53, Moscow, 119333, Russia
| | - Jacob B Khurgin
- Department of ECE, John Hopkins University, Baltimore, Maryland 21218, United States
| | - Igor V Smetanin
- P. N. Lebedev Physical Institute, Russian Academy of Sciences, Leninskiy Pr. 53, Moscow, 119333, Russia
| | - Igor E Protsenko
- P. N. Lebedev Physical Institute, Russian Academy of Sciences, Leninskiy Pr. 53, Moscow, 119333, Russia
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Vincenti MA, de Ceglia D, Scalora M. ENZ materials and anisotropy: enhancing nonlinear optical interactions at the nanoscale. OPTICS EXPRESS 2020; 28:31180-31196. [PMID: 33115097 DOI: 10.1364/oe.404107] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/30/2020] [Accepted: 09/09/2020] [Indexed: 06/11/2023]
Abstract
Epsilon-near-zero materials are exceptional candidates for studying electrodynamics and nonlinear optical processes at the nanoscale. We demonstrate that by alternating a metal and a highly doped conducting-oxide, the epsilon-near-zero regime may be accessed resulting in an anisotropic, composite nanostructure that significantly improves nonlinear interactions. The investigation of the multilayer nanostructure reveals the actual role of the anisotropy, showing that high degrees of anisotropy might be necessary to effectively boost nonlinear processes. Moreover, using a microscopic, hydrodynamic approach we shed light on the roles of two competing contributions that are for the most part overlooked but that can significantly modify linear and nonlinear responses of the structure: nonlocal effects, which blueshift the resulting resonance, and the hot electrons nonlinearity, which redshifts the plasma frequency as the effective mass of free electrons increases as a function of incident power density and enhances the nonlinear signal by several orders of magnitude. Finally, we show that, even in the absence of second order bulk nonlinearity, second order nonlinear processes are also significantly enhanced by the layered structure.
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Pérez-Escudero JM, Buldain I, Beruete M, Goicoechea J, Liberal I. Silicon carbide as a material-based high-impedance surface for enhanced absorption within ultra-thin metallic films. OPTICS EXPRESS 2020; 28:31624-31636. [PMID: 33115132 DOI: 10.1364/oe.402397] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/10/2020] [Accepted: 09/09/2020] [Indexed: 06/11/2023]
Abstract
The absorption of infrared radiation within ultra-thin metallic films is technologically relevant for different thermal engineering applications and optoelectronic devices, as well as for fundamental research on sub-nanometer and atomically-thin materials. However, the maximal attainable absorption within an ultra-thin metallic film is intrinsically limited by both its geometry and material properties. Here, we demonstrate that material-based high-impedance surfaces enhance the absorptivity of the films, potentially leading to perfect absorption for optimal resistive layers, and a fourfold enhancement for films at deep nanometer scales. Moreover, material-based high-impedance surfaces do not suffer from spatial dispersion and the geometrical restrictions of their metamaterial counterparts. We provide a proof-of-concept experimental demonstration by using titanium nanofilms on top of a silicon carbide substrate.
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Ikhsanov RS, Protsenko IE, Smetanin IV, Uskov AV. Landau broadening of plasmonic resonances in the Mie theory. OPTICS LETTERS 2020; 45:2644-2647. [PMID: 32356837 DOI: 10.1364/ol.389329] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/11/2020] [Accepted: 03/27/2020] [Indexed: 06/11/2023]
Abstract
Landau damping in the metal nanosphere is considered beyond the quasistatic approximation with the use of the exact Mie theory when an incident plane wave can excite not only the dipole mode but also higher-order modes. In resonance approximation, when one considers excitation of a single mode, the analytical formula for the Landau damping coefficient for various modes has been derived. It was demonstrated that the simultaneous excitation of several eigenmodes, which are overlapped in the frequency domain, can lead to substantial correction of the Landau damping coefficients for the modes.
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Yoo D, Vidal-Codina F, Ciracì C, Nguyen NC, Smith DR, Peraire J, Oh SH. Modeling and observation of mid-infrared nonlocality in effective epsilon-near-zero ultranarrow coaxial apertures. Nat Commun 2019; 10:4476. [PMID: 31578373 PMCID: PMC6775091 DOI: 10.1038/s41467-019-12038-3] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2019] [Accepted: 08/17/2019] [Indexed: 11/09/2022] Open
Abstract
With advances in nanofabrication techniques, extreme-scale nanophotonic devices with critical gap dimensions of just 1-2 nm have been realized. Plasmons in such ultranarrow gaps can exhibit nonlocal response, which was previously shown to limit the field enhancement and cause optical properties to deviate from the local description. Using atomic layer lithography, we create mid-infrared-resonant coaxial apertures with gap sizes as small as 1 nm and observe strong evidence of nonlocality, including spectral shifts and boosted transmittance of the cutoff epsilon-near-zero mode. Experiments are supported by full-wave 3-D nonlocal simulations performed with the hybridizable discontinuous Galerkin method. This numerical method captures atomic-scale variations of the electromagnetic fields while efficiently handling extreme-scale size mismatch. Combining atomic-layer-based fabrication techniques with fast and accurate numerical simulations provides practical routes to design and fabricate highly-efficient large-area mid-infrared sensors, antennas, and metasurfaces.
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Affiliation(s)
- Daehan Yoo
- Department of Electrical and Computer Engineering, University of Minnesota, Minneapolis, MN, 55455, USA
| | - Ferran Vidal-Codina
- Department of Aeronautics and Astronautics, Massachusetts Institute of Technology, Cambridge, MA, 02139, USA
| | - Cristian Ciracì
- Center for Biomolecular Nanotechnologies, Istituto Italiano di Tecnologia, Via Barsanti 14, 73010, Arnesano (LE), Italy.
| | - Ngoc-Cuong Nguyen
- Department of Aeronautics and Astronautics, Massachusetts Institute of Technology, Cambridge, MA, 02139, USA
| | - David R Smith
- Center for Metamaterial and Integrated Plasmonics, Department of Electrical and Computer Engineering, Pratt School of Engineering, Duke University, Durham, NC, 27708, USA
| | - Jaime Peraire
- Department of Aeronautics and Astronautics, Massachusetts Institute of Technology, Cambridge, MA, 02139, USA.
| | - Sang-Hyun Oh
- Department of Electrical and Computer Engineering, University of Minnesota, Minneapolis, MN, 55455, USA.
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