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14 pages, 712 KiB

Open AccessArticle

Effective Control of the Optical Bistability of a Three-Level Quantum Emitter near a Nanostructured Plasmonic Metasurface

by Hamid R. Hamedi, Emmanuel Paspalakis and Vassilios Yannopapas

Photonics 2021, 8(7), 285; https://doi.org/10.3390/photonics8070285 - 17 Jul 2021

Cited by 3 | Viewed by 4091

Abstract

We study, theoretically, the phenomena optical bistability and multistability of a hybrid quantum-plasmonic system immersed within an optical ring cavity. The hybrid quantum-plasmonic system consists of a three-level V-type quantum emitter and a two-dimensional plasmonic metasurface of gold nanoshells. The quantum emitter [...] Read more.

We study, theoretically, the phenomena optical bistability and multistability of a hybrid quantum-plasmonic system immersed within an optical ring cavity. The hybrid quantum-plasmonic system consists of a three-level V-type quantum emitter and a two-dimensional plasmonic metasurface of gold nanoshells. The quantum emitter and the plasmonic metasurface are placed in close proximity to each other so that a strong quantum interference of spontaneous emission occurs, which enables the strong modification of optical-bistability/ multistability hysteresis curves. Along with this, the strong interaction between the emitter and the plasmonic metasurface allows for active control of the corresponding bistable threshold intensity. Furthermore, we show that by varying the metasurface-emitter separation, a transition from bistability to multistability of the hybrid system is observed. Lastly, by introducing an additional incoherent pumping in the system, we have the emergence of phenomena, such as probe absorption and gain, with or without population inversion. The results may find technological application in on-chip nanoscale photonic devices, optoelectronics and solid-state quantum information science. Full article

(This article belongs to the Special Issue Plasmonic Metasurfaces)

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9 pages, 1471 KiB

Open AccessEditor’s ChoiceArticle

Electron Spill-Out Effect in Singular Metasurfaces

by Fan Yang and Kun Ding

Photonics 2021, 8(5), 154; https://doi.org/10.3390/photonics8050154 - 05 May 2021

Cited by 1 | Viewed by 2785

Abstract

The electron spill-out effect is considered in a singular metasurface. Using the hydrodynamic model, we found that electron spill-out effectively smears the sharp singularity. The introduction of the electron spill-out effect also significantly changes the reflection spectrum, charge distribution, field profile for a [...] Read more.

The electron spill-out effect is considered in a singular metasurface. Using the hydrodynamic model, we found that electron spill-out effectively smears the sharp singularity. The introduction of the electron spill-out effect also significantly changes the reflection spectrum, charge distribution, field profile for a singular metasurface. Therefore, this spill-out contribution is crucial and cannot be ignored for a realistic description of optical response in a singular system. Full article

(This article belongs to the Special Issue Plasmonic Metasurfaces)

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8 pages, 1677 KiB

Open AccessCommunication

Phase-Controlled Planar Metalenses for High-Resolution Terahertz Focusing

by Xin Yu, Yun Shen, Guohong Dai, Liner Zou, Tailin Zhang and Xiaohua Deng

Photonics 2021, 8(5), 143; https://doi.org/10.3390/photonics8050143 - 26 Apr 2021

Cited by 6 | Viewed by 2756

Abstract

We experimentally demonstrate that high-resolution terahertz focusing can be realized in planar metalenses, which consist of arrays of different V-shaped antenna units on a silicon substrate. Numerical results show that a larger numerical aperture of metalenses can provide smaller full width at half [...] Read more.

We experimentally demonstrate that high-resolution terahertz focusing can be realized in planar metalenses, which consist of arrays of different V-shaped antenna units on a silicon substrate. Numerical results show that a larger numerical aperture of metalenses can provide smaller full width at half maximum of field distribution, leading to higher spatial resolution. The measurement of fabricated metalenses samples was performed by a terahertz near-field imaging system, and experimental results agree well with the numerical prediction. Especially for 1.1 THz incident light, when the numerical aperture increases from 0.79 to 0.95, the full width at half maximum correspondingly decreases from 343 μm to 206 μm, offering an improvement of spatial resolution. Full article

(This article belongs to the Special Issue Plasmonic Metasurfaces)

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7 pages, 2313 KiB

Open AccessCommunication

Plasmonic Fishnet Structures for Dual Band THz Left-Handed Metamaterials

by Shaohua Zhang, Zhifu Wei, Ling Xu, Jianwei Xu, Shoujian Ouyang and Yun Shen

Photonics 2021, 8(4), 116; https://doi.org/10.3390/photonics8040116 - 09 Apr 2021

Cited by 2 | Viewed by 1766

Abstract

Plasmonic fishnet structures are proposed to realize dual-band terahertz (THz) left-handed metamaterials (LHMs). The calculated permittivity ε and permeability μ of single-layer LHMs show that ε < 0 and μ < 0 can be simultaneously satisfied in two frequency bands, resulting in dual-band [...] Read more.

Plasmonic fishnet structures are proposed to realize dual-band terahertz (THz) left-handed metamaterials (LHMs). The calculated permittivity ε and permeability μ of single-layer LHMs show that ε < 0 and μ < 0 can be simultaneously satisfied in two frequency bands, resulting in dual-band LHMs. The electric and magnetic field distributions are consistent with the current distributions and confirm the physical mechanism of negative permeability. Furthermore, the existence of negative refraction is validated by a stacked LHMs prism with an angle of 1.79°. It is shown that at 2.04–2.42 THz and 3.12–3.28 THz bands, negative refractive indices of the prism can be obtained, facilitating the practical application of LHMs in THz image, sensor, detection, communication, and so on. Full article

(This article belongs to the Special Issue Plasmonic Metasurfaces)

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11 pages, 9845 KiB

Open AccessCommunication

Multipolar Lattice Resonances in Plasmonic Finite-Size Metasurfaces

by Artem S. Kostyukov, Ilia L. Rasskazov, Valeriy S. Gerasimov, Sergey P. Polyutov, Sergey V. Karpov and Alexander E. Ershov

Photonics 2021, 8(4), 109; https://doi.org/10.3390/photonics8040109 - 06 Apr 2021

Cited by 13 | Viewed by 2767

Abstract

Collective lattice resonances in regular arrays of plasmonic nanoparticles have attracted much attention due to a large number of applications in optics and photonics. Most of the research in this field is concentrated on the electric dipolar lattice resonances, leaving higher-order multipolar lattice [...] Read more.

Collective lattice resonances in regular arrays of plasmonic nanoparticles have attracted much attention due to a large number of applications in optics and photonics. Most of the research in this field is concentrated on the electric dipolar lattice resonances, leaving higher-order multipolar lattice resonances in plasmonic nanostructures relatively unexplored. Just a few works report exceptionally high-Q multipolar lattice resonances in plasmonic arrays, but only with infinite extent (i.e., perfectly periodic). In this work, we comprehensively study multipolar collective lattice resonances both in finite and in infinite arrays of Au and Al plasmonic nanoparticles using a rigorous theoretical treatment. It is shown that multipolar lattice resonances in the relatively large (up to 6400 nanoparticles) finite arrays exhibit broader full width at half maximum (FWHM) compared to similar resonances in the infinite arrays. We argue that our results are of particular importance for the practical implementation of multipolar lattice resonances in different photonics applications. Full article

(This article belongs to the Special Issue Plasmonic Metasurfaces)

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14 pages, 24671 KiB

Open AccessEditor’s ChoiceArticle

Topological-Insulator-Based Gap-Surface Plasmon Metasurfaces

by Andreas Aigner, Stefan A. Maier and Haoran Ren

Photonics 2021, 8(2), 40; https://doi.org/10.3390/photonics8020040 - 04 Feb 2021

Cited by 3 | Viewed by 5173

Abstract

Topological insulators (TIs) have unique highly conducting symmetry-protected surface states while the bulk is insulating, making them attractive for various applications in condensed matter physics. Recently, topological insulator materials have been tentatively applied for both near- and far-field wavefront manipulation of electromagnetic waves, [...] Read more.

Topological insulators (TIs) have unique highly conducting symmetry-protected surface states while the bulk is insulating, making them attractive for various applications in condensed matter physics. Recently, topological insulator materials have been tentatively applied for both near- and far-field wavefront manipulation of electromagnetic waves, yielding superior plasmonic properties in the ultraviolet (UV)-to-visible wavelength range. However, previous reports have only demonstrated inefficient wavefront control based on binary metasurfaces that were digitalized on a TI thin film or non-directional surface plasmon polariton (SPP) excitation. Here, we numerically demonstrated the plasmonic capabilities of the TI Bi₂Te₃ as a material for gap–surface plasmon (GSP) metasurfaces. By employing the principle of the geometric phase, a far-field beam-steering metasurface was designed for the visible spectrum, yielding a cross-polarization efficiency of 34% at 500 nm while suppressing the co-polarization to 0.08%. Furthermore, a birefringent GSP metasurface design was studied and found to be capable of directionally exciting SPPs depending on the incident polarization. Our work forms the basis for accurately controlling the far- and near-field responses of TI-based GSP metasurfaces in the visible spectral range. Full article

(This article belongs to the Special Issue Plasmonic Metasurfaces)

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17 pages, 10058 KiB

Open AccessEditor’s ChoiceArticle

Near- and Far-Field Excitation of Topological Plasmonic Metasurfaces

by Matthew Proctor, Xiaofei Xiao, Richard V. Craster, Stefan A. Maier, Vincenzo Giannini and Paloma Arroyo Huidobro

Photonics 2020, 7(4), 81; https://doi.org/10.3390/photonics7040081 - 24 Sep 2020

Cited by 9 | Viewed by 3608

Abstract

The breathing honeycomb lattice hosts a topologically non-trivial bulk phase due to the crystalline-symmetry of the system. Pseudospin-dependent edge states, which emerge at the interface between trivial and non-trivial regions, can be used for the directional propagation of energy. Using the plasmonic metasurface [...] Read more.

The breathing honeycomb lattice hosts a topologically non-trivial bulk phase due to the crystalline-symmetry of the system. Pseudospin-dependent edge states, which emerge at the interface between trivial and non-trivial regions, can be used for the directional propagation of energy. Using the plasmonic metasurface as an example system, we probe these states in the near- and far-field using a semi-analytical model. We provide the conditions under which directionality was observed and show that it is source position dependent. By probing with circularly-polarised magnetic dipoles out of the plane, we first characterise modes along the interface in terms of the enhancement of source emissions due to the metasurface. We then excite from the far-field with non-zero orbital angular momentum beams. The position-dependent directionality holds true for all classical wave systems with a breathing honeycomb lattice. Our results show that a metasurface in combination with a chiral two-dimensional material, could be used to guide light effectively on the nanoscale. Full article

(This article belongs to the Special Issue Plasmonic Metasurfaces)

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11 pages, 3110 KiB

Open AccessCommunication

Robust Conformal Perfect Absorber Involving Lossy Ultrathin Film

by Lei Zhang, Kun Wang, Hui Chen and Yanpeng Zhang

Photonics 2020, 7(3), 57; https://doi.org/10.3390/photonics7030057 - 06 Aug 2020

Cited by 1 | Viewed by 2235

Abstract

Perfect absorbers have been extensively investigated due to their significant value in solar cell, photodetection, and stealth technologies. Various subwavelength structures have been proposed to improve the absorption performances, such as high absorptance, broad band, and wide absorption angle. However, excellent performances usually [...] Read more.

Perfect absorbers have been extensively investigated due to their significant value in solar cell, photodetection, and stealth technologies. Various subwavelength structures have been proposed to improve the absorption performances, such as high absorptance, broad band, and wide absorption angle. However, excellent performances usually put forward higher requirements on structural designs, such as varying the geometry sizes or shapes to fit different center wavelengths, which inevitably increases the fabrication burden. Here, a planar sandwich structure involving a layer of highly lossy material is proposed to achieve a robust perfect absorption with 95% absorptance ranging from the visible to near infrared range. Such an excellent absorption performance is also polarization-independent and applicable to a wide incident angle. Furthermore, the proposed design can also be applied to conformal surfaces with a 90% fluctuation over a steep surface. We believe that the proposed perfect absorber with distinguished performances can find wide application. Full article

(This article belongs to the Special Issue Plasmonic Metasurfaces)

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Review

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21 pages, 7371 KiB

Open AccessEditor’s ChoiceReview

Nonreciprocal and Topological Plasmonics

by Kunal Shastri, Mohamed Ismail Abdelrahman and Francesco Monticone

Photonics 2021, 8(4), 133; https://doi.org/10.3390/photonics8040133 - 20 Apr 2021

Cited by 19 | Viewed by 4395

Abstract

Metals, semiconductors, metamaterials, and various two-dimensional materials with plasmonic dispersion exhibit numerous exotic physical effects in the presence of an external bias, for example an external static magnetic field or electric current. These physical phenomena range from Faraday rotation of light propagating in [...] Read more.

Metals, semiconductors, metamaterials, and various two-dimensional materials with plasmonic dispersion exhibit numerous exotic physical effects in the presence of an external bias, for example an external static magnetic field or electric current. These physical phenomena range from Faraday rotation of light propagating in the bulk to strong confinement and directionality of guided modes on the surface and are a consequence of the breaking of Lorentz reciprocity in these systems. The recent introduction of relevant concepts of topological physics, translated from condensed-matter systems to photonics, has not only given a new perspective on some of these topics by relating certain bulk properties of plasmonic media to the surface phenomena, but has also led to the discovery of new regimes of truly unidirectional, backscattering-immune, surface-wave propagation. In this article, we briefly review the concepts of nonreciprocity and topology and describe their manifestation in plasmonic materials. Furthermore, we use these concepts to classify and discuss the different classes of guided surface modes existing on the interfaces of various plasmonic systems. Full article

(This article belongs to the Special Issue Plasmonic Metasurfaces)

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