Artículos de revistas: "Magnetic dipole nanoantenna"

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Fujii, Minoru, and Hiroshi Sugimoto. "(Invited, Digital Presentation) Enhancement of Magnetic Dipole Transition of Molecules By Silicon Nanoparticle Nanoantenna." ECS Meeting Abstracts MA2022-01, no. 20 (2022): 1081. http://dx.doi.org/10.1149/ma2022-01201081mtgabs.

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A nanoantenna is a nanodevice that manipulates light propagation and enhances light-matter interaction at the nanoscale. Integration of an emitter into a nanoantenna capable of increasing local density of photonic states at the emission wavelength results in the enhanced spontaneous emission rate (Purcell effect). The most widely studied nanoantennas for the Purcell enhancement are plasmonic nanoantennas made from gold or silver nanostructures supporting surface plasmon resonances. In most cases, nanoantennas have been used for the enhancement of electric dipole-allowed transition of a molecule. In addition, recently, nanoantennas capable of enhancing magnetic dipole transition of a molecule are attracting attention. For the magnetic Purcell enhancement, nanoantennas have to have magnetic resonances at the optical frequency. Although it is possible to achieve magnetic resonances at the optical frequency by plasmonic nanostructures, the inherent absorption loss of noble metals limits the magnetic Purcell enhancement. On the other hand, nanoparticles of high refractive index dielectrics inherently have low-loss magnetic-type Mie resonances at the optical frequency, and thus are potentially more attractive as a material to realize large magnetic Purcell enhancement. We have developed spherical nanoparticles of crystalline silicon (Si) having the magnetic dipole (MD) and quadrupole (MQ) Mie resonances at the optical frequency [1]. In this work, to demonstrate the potential of a Si nanoparticle as a nanoantenna for the magnetic Purcell enhancement, we develop a composite nanoparticle, that is, a Si nanosphere decorated with europium ion (Eu3+) complexes, in which magnetic dipole emission of Eu3+ is efficiently coupled to the magnetic Mie modes of the nanosphere [2]. We systematically investigate the light scattering and photoluminescence spectra of the coupled system by means of single particle spectroscopy. The results are shown in Figure 1. By tuning the MQ Mie resonance of a Si nanosphere to the 5D0-7F1 magnetic dipole transition of Eu3+, the branching ratio between the magnetic and electric dipole (5D0-7F2) transitions is enhanced up to 7 times. The observed large magnetic Purcell enhancement offers an opportunity to develop novel fluorophores with enhanced magnetic dipole emission. Furthermore, the enhanced magnetic field of dielectric Mie resonators enhances otherwise very weak absorption due to magnetic dipole transition, and makes direct excitation of triplet states of a molecule possible [3]. Direct excitation of triplet states reduces photon energy necessary for energy conversion and chemical reactions utilizing a triplet state compared to a conventional process involving singlet-singlet excitation and singlet-triplet intersystem crossing. [1] H. Sugimoto, et. al., "Mie Resonator Color Inks of Monodispersed and Perfectly Spherical Crystalline Silicon Nanoparticles" Advanced Optical Materials, 8 (2020) 2000033. [2] H. Sugimoto, and Minoru Fujii, "Magnetic Purcell Enhancement by Magnetic Quadrupole Resonance of Dielectric Nanosphere Antenna", ACS Photonics, 8 (2021) 1794. [3] H. Sugimoto, et. al., "Direct Excitation of Triplet State of Molecule by Enhanced Magnetic Field of Dielectric Metasurfaces", Small, 2021, DOI: 10.1002/smll.202104458. Figure 1: Photoluminescence (red curves) and scattering (black curves) spectra of single Si naosphere-Eu3+ complex composite nanoparticles with different Si nanosphere diameters. The diameters are shown at the right end of the figure. Figure 1

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2

Agrahari, Rajan, and Hadi K. Shamkhi. "Highly Directive All-Dielectric Nanoantenna." Journal of Physics: Conference Series 2015, no. 1 (2021): 012003. http://dx.doi.org/10.1088/1742-6596/2015/1/012003.

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Abstract A highly directive dielectric nanoantenna in an integrated chip may enable faster communication as their low losses and small size overcome the limitation of temperature enhancement and low data transfer rate. We optimize nanoantenna consist of Si-nanoblock in the near-infrared region to efficiently transfer a point dipole light to a highly directive light in the far-field region. We engineer the intrinsic electric and magnetic resonances of a Si-block nanoantenna by modifying and reducing its geometrical symmetry. We realize a pronounced enhancement of directivity by systematically inducing perturbation in the Silicon block so that both its reflection and rotational symmetries are broken. Finally, we retain the traditional method to increase resonance’s coupling to outer space by introducing substrate with an increasing refractive index. We find that the directivity has boosted rapidly.

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KUMAR, V. DINESH, ABHINAV BHARDWAJ, DEEPAK MISHRA, and KIYOSHI ASAKAWA. "DIRECTIONAL AND POLARIZATION PROPERTIES OF A PLASMONIC CROSS NANOANTENNA." Journal of Nonlinear Optical Physics & Materials 19, no. 04 (2010): 517–25. http://dx.doi.org/10.1142/s0218863510005418.

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The response of dipole nanoantennas (DNAs) studied widely in optical frequency range is sensitive to polarization of incident field. In this paper, we report the implementation of a cross nanoantenna (CNA) consisting of two orthogonal DNAs with a common feedgap and investigate its directional and polarization properties and compare them with those of the DNA. Interestingly the response of CNA is independent of polarization. We can operate the CNA in turnstile mode by using two identical light sources with cross polarization in phase quadrature. In such a case the radiation from the CNA is found omnidirectional like radio frequency turnstile antenna. We believe CNA could open new possibilities to study the novel phenomenon of light matter interaction. To the best of our knowledge, this is the first report on a turnstile antenna in optical frequencies.

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4

Xu, Lei, Mohsen Rahmani, Daria Smirnova, et al. "Highly-Efficient Longitudinal Second-Harmonic Generation from Doubly-Resonant AlGaAs Nanoantennas." Photonics 5, no. 3 (2018): 29. http://dx.doi.org/10.3390/photonics5030029.

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We design an asymmetric nonlinear optical nanoantenna composed of a dielectric nanodisc and an adjacent nanobar. The proposed composite structure made of AlGaAs exhibits resonant response at both the fundamental and doubled frequencies. Being driven by the strong magnetic dipole resonance at the pump wavelength and a high-quality mode at the harmonic wavelength, the efficient second-harmonic radiation is generated predominantly along the vertical directions under the normally incident plane-wave excitation.

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5

Castanié, E., R. Vincent, R. Pierrat, and R. Carminati. "Absorption by an Optical Dipole Antenna in a Structured Environment." International Journal of Optics 2012 (2012): 1–8. http://dx.doi.org/10.1155/2012/452047.

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We compute generalized absorption and extinction cross-sections of an optical dipole nanoantenna in a structured environment. The expressions explicitly show the influence of radiation reaction and the local density of states on the intrinsic absorption properties of the antenna. Engineering the environment could allow to modify the overall absorption as well as the frequency and the linewidth of a resonant antenna. Conversely, a dipole antenna can be used to probe the photonic environment, in a similar way as a quantum emitter.

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6

Kumar, Abhinandan, and Nabin Kumar. "Rabi Waves for Excitation of Quantum Nanoantenna with Electrically Controlled Radiation Pattern and Its Application." Bulletin of Pure and Applied Sciences – Physics 42, no. 2 (2023): 84–88. http://dx.doi.org/10.48165/bpas.2023.42d.2.4.

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Rabi waves for the excitation of quantum nanoantennas with electrically controlled radiation and frequency characteristics were studied. The operational frequency of the visible range was based on the high frequency component of the current. The low frequency component and its operational frequency was in the terahertz range. The feature of the Rabi wave antenna depends on the carrier frequency on the electromagnetic field intensity. The contribution of high order magnetic multipoles became essential. The radiation properties of an antenna were the same as the ideal magnetic dipole. The antenna frequency spectrum corresponded to the amplitude modulated Rabi oscillations. The high frequency current was in the optical range in the vicinity of the quantum transition frequency. The radiation field of the nano antenna was considered equivalent to the field of magnetic dipole placed in the centre of current ring and oriented orthogonal to the ring plane. The equivalence was consequence of the electrical smallness of the antenna over the working range of frequency. The results obtained were in good agreement with previous results.

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7

Decker, M., T. Pertsch, and I. Staude. "Strong coupling in hybrid metal–dielectric nanoresonators." Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences 375, no. 2090 (2017): 20160312. http://dx.doi.org/10.1098/rsta.2016.0312.

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We study resonant photonic–plasmonic coupling between a gold dipole nanoantenna and a silicon nanodisc supporting electric and magnetic dipolar Mie-type resonances. Specifically, we consider two different cases for the mode structure of the silicon nanodisc, namely spectrally separate and spectrally matching electric and magnetic dipolar Mie-type resonances. In the latter case, the dielectric nanoparticle scatters the far fields of a unidirectional Huygens’ source. Our results reveal an anticrossing of the plasmonic dipole resonance and the magnetic Mie-type dipole resonance of the silicon nanodisc, accompanied by a clear signature of photonic–plasmonic mode hybridization in the corresponding mode profiles. These characteristics show that strong coupling is established between the two different resonant systems in the hybrid nanostructure. Furthermore, our results demonstrate that in comparison with purely metallic or dielectric nanostructures, hybrid metal–dielectric nanoresonators offer higher flexibility in tailoring the fractions of light which are transmitted, absorbed and reflected by the nanostructure over a broad range of parameters without changing its material composition. As a special case, highly asymmetric reflection and absorption properties can be achieved. This article is part of the themed issue ‘New horizons for nanophotonics’.

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8

Kalinic, Boris, Tiziana Cesca, Mirko Trevisani, Andrea Jacassi, Riccardo Sapienza, and Giovanni Mattei. "Strong Er³⁺ radiative emission enhancement by quasi-BIC modes coupling in all-dielectric slot nanoantenna arrays." EPJ Web of Conferences 287 (2023): 05002. http://dx.doi.org/10.1051/epjconf/202328705002.

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We have designed and realized all-dielectric lossless nanoantennas, in which a thin SiO2 layer doped with erbium ions is placed inside slotted silicon nanopillars arranged in a square array. The modal analysis has evi-denced that the slotted nanopillar array supports optical quasi-BIC resonances with ultra-high Q-factors (up to Q∼109), able to boost the electromagnetic local density of optical states in the optically active layer. Up to 3 orders of magnitude photoluminescence intensity increment and 2 orders of magnitude decay rate enhancement have been measured at room temperature when the Er3+ emission at about λ=1540 nm couples with the quasi-BIC resonances. Furthermore, by tailoring the nanopillar aspect ratio, the slot geometry has been exploited to obtain selective enhancements of the electric or magnetic dipole contribution to Er3+ radiative transitions in the NIR, keeping the emitter quantum efficiency almost unitary. Finally, by computing the angularly resolved elec-tromagnetic field enhancement inside the nanoslot, the nanoantenna directivity has been designed, proving that strong beaming effects can be obtained. Our findings have a direct impact on the development of bright and effi-cient photon sources operating at telecom wavelength that are of primary importance for quantum nanophotonic applications.

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9

Pakizeh, Tavakol. "Unidirectional radiation of a magnetic dipole coupled to an ultracompact nanoantenna at visible wavelengths." Journal of the Optical Society of America B 29, no. 9 (2012): 2446. http://dx.doi.org/10.1364/josab.29.002446.

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10

Kroychuk, Maria K., Alexander S. Shorokhov, Damir F. Yagudin, et al. "Quantum Dot Photoluminescence Enhancement in GaAs Nanopillar Oligomers Driven by Collective Magnetic Modes." Nanomaterials 13, no. 3 (2023): 507. http://dx.doi.org/10.3390/nano13030507.

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Single photon sources based on semiconductor quantum dots are one of the most prospective elements for optical quantum computing and cryptography. Such systems are often based on Bragg resonators, which provide several ways to control the emission of quantum dots. However, the fabrication of periodic structures with many thin layers is difficult. On the other hand, the coupling of single-photon sources with resonant nanoclusters made of high-index dielectric materials is known as a promising way for emission control. Our experiments and calculations show that the excitation of magnetic Mie-type resonance by linearly polarized light in a GaAs nanopillar oligomer with embedded InAs quantum dots leads to quantum emitters absorption efficiency enhancement. Moreover, the nanoresonator at the wavelength of magnetic dipole resonance also acts as a nanoantenna for a generated signal, allowing control over its radiation spatial profile. We experimentally demonstrated an order of magnitude emission enhancement and numerically reached forty times gain in comparison with unstructured film. These findings highlight the potential of quantum dots coupling with Mie-resonant oligomers collective modes for nanoscale single-photon sources development.

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11

Tanaka, Yoshito Y., Tomoya Kimura, and Tsutomu Shimura. "Unidirectional emission of phase-controlled second harmonic generation from a plasmonic nanoantenna." Nanophotonics 10, no. 18 (2021): 4601–9. http://dx.doi.org/10.1515/nanoph-2021-0470.

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Abstract Shaping the emission pattern of second harmonic (SH) generation from plasmonic nanoparticles is important for practical applications in nonlinear nanophotonics but is rendered challenging by the complex second-order nonlinear-optical processes. Here, we theoretically and experimentally demonstrate that a pair of V- and Y-shaped gold nanoparticles directs the SH emission perpendicularly to an incident light direction. Owing to spatial overlap of two orthogonal plasmonic dipole modes at the fundamental and SH wavelengths of the individual particles, surface SH polarizations induced by the fundamental field is efficiently near-field coupled to the SH plasmon mode, resulting in dipolar SH emission from the individual particles. Moreover, the phase of this emission can be tuned simply by altering the part of the Y-particle shape, which changes the SH plasmon resonance while keeping the fundamental resonance. Our approach is a promising platform for engineering not only directional nonlinear nanoantennas but also nonlinear metamaterials.

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12

Dyshlyuk, Anton V., Andrey A. Bogdanov, and Oleg B. Vitrik. "A simple analytic approach to the problem of excitation of surface plasmon polaritons with a dipole nanoantenna." Photonics and Nanostructures - Fundamentals and Applications 43 (February 2021): 100895. http://dx.doi.org/10.1016/j.photonics.2021.100895.

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13

Borovkov, Dmitrii, and Adrià Canós Valero. "Toroidal anapole with point magnetic dipoles." Journal of Physics: Conference Series 2388, no. 1 (2022): 012018. http://dx.doi.org/10.1088/1742-6596/2388/1/012018.

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Abstract The role of multipolar expansion of the localized current is significant in a broad range of disciplines in the physics of nowadays. It is actively used in such problems as the design of nanoantennas in photonics or the description of exotic states of matter. The toroidal multipoles are the third group of multipoles which complements the electric and magnetic multipolar families. The investigation of toroidal multipoles is important because of their role in the formation of so-called anapole states, non-radiating sources. The further study showed that there are also exist the higher-order toroidal dipoles or mean-square radii, which are equivalent. Here we suggest the structure which consists of point magnetic dipoles and supports the toroidal anapole state, which is obtained with the destructive interference of electric toroidal dipole with the first mean-square radius of the electric toroidal dipole. We also present an analytical condition for toroidal anapole with this system of point magnetic dipoles placed in two circles.

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14

Raya, Andrés M., David Fuster, and José M. Llorens. "Numerical Study on Mie Resonances in Single GaAs Nanomembranes." Nanomaterials 9, no. 6 (2019): 856. http://dx.doi.org/10.3390/nano9060856.

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GaAs nanomembranes grown by selective area epitaxy are novel structures. The high refractive index of GaAs makes them good candidates for nanoantennas. We numerically studied the optical modal structure of the resonator. The nanomembrane geometry introduces a strong light-polarization dependence. The scattering is dominated by an electric dipole contribution for polarization along the nanomembrane long dimension and by a magnetic dipole contribution in the orthogonal direction. The dependence on the geometry of the resonances close to the GaAs band gap was modeled by a single coefficient. It describes the resonance shifts against up-to 40% changes in length, height, and width. We showed that the nanomembranes exhibited field enhancement, far-field directionality, and tunability with the GaAs band gap. All these elements confirm their great potential as nanoantennas.

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Czajkowski, Krzysztof M., Maria Bancerek, Alexander Korneluk, Dominika Świtlik, and Tomasz J. Antosiewicz. "Polarization-dependent mode coupling in hyperbolic nanospheres." Nanophotonics 10, no. 10 (2021): 2737–51. http://dx.doi.org/10.1515/nanoph-2021-0247.

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Abstract Hyperbolic materials offer much wider freedom in designing optical properties of nanostructures than ones with isotropic and elliptical dispersion, both metallic or dielectric. Here, we present a detailed theoretical and numerical study on the unique optical properties of spherical nanoantennas composed of such materials. Hyperbolic nanospheres exhibit a rich modal structure that, depending on the polarization and direction of incident light, can exhibit either a full plasmonic-like response with multiple electric resonances, a single, dominant electric dipole or one with mixed magnetic and electric modes with an atypical reversed modal order. We derive conditions for observing these resonances in the dipolar approximation and offer insight into how the modal response evolves with the size, material composition, and illumination. Specifically, the origin of the magnetic dipole mode lies in the hyperbolic dispersion and its existence is determined by two diagonal permittivity components of different sign. Our analysis shows that the origin of this unusual behavior stems from complex coupling between electric and magnetic multipoles, which leads to very strong scattering or absorbing modes. These observations assert that hyperbolic nanoantennas offer a promising route towards novel light–matter interaction regimes.

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16

Mivelle, Mathieu, Thierry Grosjean, Geoffrey W. Burr, Ulrich C. Fischer, and Maria F. Garcia-Parajo. "Strong Modification of Magnetic Dipole Emission through Diabolo Nanoantennas." ACS Photonics 2, no. 8 (2015): 1071–76. http://dx.doi.org/10.1021/acsphotonics.5b00128.

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17

Giordano, Maria Caterina, Matteo Barelli, Giuseppe Della Valle, and Francesco Buatier de Mongeot. "Self-Organized Conductive Gratings of Au Nanostripe Dimers Enable Tunable Plasmonic Activity." Applied Sciences 10, no. 4 (2020): 1301. http://dx.doi.org/10.3390/app10041301.

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Plasmonic metasurfaces based on quasi-one-dimensional (1D) nanostripe arrays are homogeneously prepared over large-area substrates (cm2), exploiting a novel self-organized nanofabrication method. Glass templates are nanopatterned by ion beam-induced anisotropic nanoscale wrinkling, enabling the maskless confinement of quasi-1D arrays of out-of-plane tilted gold nanostripes, behaving as transparent wire-grid polarizer nanoelectrodes. These templates enable the dichroic excitation of localized surface plasmon resonances, easily tunable over a broadband spectrum from the visible to the near- and mid-infrared, by tailoring the nanostripes’ shape and/or changing the illumination conditions. The controlled self-organized method allows the engineering of the nanoantennas’ morphology in the form of Au-SiO2-Au nanostripe dimers, which show hybridized plasmonic resonances with enhanced tunability. Under this condition, superior near-field amplification is achievable for the excitation of the hybridized magnetic dipole mode, as pointed out by numerical simulations. The high efficiency of these plasmonic nanoantennas, combined with the controlled tuning of the resonant response, opens a variety of applications for these cost-effective templates, ranging from biosensing and optical spectroscopies to high-resolution molecular imaging and nonlinear optics.

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18

Borovkov, Dmitrii, and Adrià Canós Valero. "On the link between mean square-radii and high-order toroidal moments." Journal of Physics: Conference Series 2015, no. 1 (2021): 012021. http://dx.doi.org/10.1088/1742-6596/2015/1/012021.

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Abstract Multipole expansions of the source play an important role in a broad range of disciplines in modern physics, ranging from the description of exotic states of matter to the design of nanoantennas in photonics. Within the context of the latter, toroidal multipoles, a third group of multipoles complementing the well-known electric and magnetic ones, have been widely investigated since they lead to the formation of non-radiating sources. In the last years, however, the photonics community has brought to light the existence of a fourth type of multipoles that is commonly overlooked. Currently, different groups have provided different mathematical expressions to describe such sources, and they have been coined with different names; on the one hand mean-square radii, and on the other hand, as high order toroidal moments. Despite their clear physical similarity, a formal relation between the two has not yet been established. While explicit formulas for both types have been derived, they are not expressed in the same basis, and therefore it is not possible to draw a clear physical connection between them. In this contribution, we will bridge this gap and rigorously derive the connection between the two representations, taking as an example the cases of the nth order mean square radius of the electric dipole and the nth order electric toroidal dipole. Our results conclusively show that both types of representations are exactly equivalent up to a prefactor.

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19

Wang, Xinghua, Yunbao Zheng, Min Ouyang, Haihua Fan, Qiaofeng Dai, and Haiying Liu. "Dual-Wavelength Forward-Enhanced Directional Scattering and Second Harmonic Enhancement in Open-Hole Silicon Nanoblock." Nanomaterials 12, no. 23 (2022): 4259. http://dx.doi.org/10.3390/nano12234259.

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Nanostructures with appropriate sizes can limit light-matter interaction and support electromagnetic multipole resonance. The interaction between light and nanostructures is intimately related to manipulating the direction of scattered light in the far field as well as the electromagnetic field in the near field. In this paper, we demonstrate dual-wavelength directional forward-scattering enhancement in an individual open-hole silicon nanoblock (OH-SiNB) and simultaneously achieve bulk and surface electromagnetic field localization. The second harmonic generation is enhanced using electromagnetic field localization on the square hole surface. Numerical simulations reveal that the resonance modes, at λ1 = 800 nm and λ2 = 1190 nm, approximately satisfy the Kerker condition. In the near field, the magnetic dipole modes at dual wavelength all satisfy the boundary condition that the normal component of the electric displacement is continuous on the square holes surface, thus obtaining the surface electromagnetic field localization. Moreover, highly efficient second harmonic generation can be achieved at dual wavelengths using the surface electromagnetic field localization and the increased surface area of the square holes. Our results provide a new strategy for the integration of nanoantennas and nonlinear optoelectronic devices in optical chips.

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Hu, Hong-Gang, Min Yang, Peng Yue, Ya-Ting Bai, Wen-Jie Wang, and Shao-Ding Liu. "Second-harmonic generation with metal/dielectric/metal hybridized nanoantennas: enhanced efficiency, reduced mode volume and ideal magnetic/electric dipole scattering." Journal of Physics D: Applied Physics 53, no. 21 (2020): 215101. http://dx.doi.org/10.1088/1361-6463/ab768d.

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21

Jiang, Hui, Yangjian Cai, and Zhanghua Han. "Strong second-harmonic generation in dielectric optical nanoantennas resulting from the hybridization of magnetic dipoles and lattice resonances." Journal of the Optical Society of America B 37, no. 11 (2020): 3146. http://dx.doi.org/10.1364/josab.402624.

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22

García‐Puente, Yalina, and Raman Kashyap. "Magnetic Purcell Enhancement in a Nanoantenna‐Spherical Bragg Resonator Coupled System." Annalen der Physik, October 2, 2023. http://dx.doi.org/10.1002/andp.202300147.

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AbstractIn this work, a novel approach for enhancing magnetic fields in all‐dielectric nanoantennas using Spherical Bragg Resonators (SBR) is proposed, which can boost quantum emitters' magnetic transitions. A matrix method has been used to optimize the magnetic dipole resonance of a SiO2/Si core‐shell spherical nanoantenna. The radiative and non‐radiative decay rate of a Eu3+ emitter with a quantum efficiency of ∼80% is studied. The findings revealed that the magnetic dipole nanoantenna resonance coupling with the SBR mode significantly enhances the modal magnetic field. A 4‐layer SiO2/Si SBR results in a Purcell factor of , the highest it has found in the literature, to the best of the knowledge. The work offers a theoretical demonstration of the potential of SBR to improve the performance of dielectric nanoantennas.

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23

Rusak, Evgenia, Jakob Straubel, Piotr Gładysz, et al. "Enhancement of and interference among higher order multipole transitions in molecules near a plasmonic nanoantenna." Nature Communications 10, no. 1 (2019). http://dx.doi.org/10.1038/s41467-019-13748-4.

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AbstractSpontaneous emission of quantum emitters can be modified by their optical environment, such as a resonant nanoantenna. This impact is usually evaluated under assumption that each molecular transition is dominated only by one multipolar channel, commonly the electric dipole. In this article, we go beyond the electric dipole approximation and take light-matter coupling through higher-order multipoles into account. We investigate a strong enhancement of the magnetic dipole and electric quadrupole emission channels of a molecule adjacent to a plasmonic nanoantenna. Additionally, we introduce a framework to study interference effects between various transition channels in molecules by rigorous quantum-chemical calculations of their multipolar moments and a consecutive investigation of the transition rate upon coupling to a nanoantenna. We predict interference effects between these transition channels, which allow in principle for a full suppression of radiation by exploiting destructive interference, waiving limitations imposed on the emitter’s coherence time by spontaneous emission.

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Zhang Han-mou, Xiao Fajun, and Zhao Jianlin. "Unidirectional scattering of Si ring-Au split ring nanoantenna excited by a tightly focused azimuthally polarized beam." Acta Physica Sinica, 2022, 0. http://dx.doi.org/10.7498/aps.71.20212212.

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Unidirectional scattering of various plasmonic nanoantennas has been extensively studied, giving birth to applications such as optical sensors, solar cells, spectroscopy and light-emitting devices. The directional scattering of magnetic nanoantennas remains unexplored, though obvious benefits of artificial magnetism applications including metamaterials, cloaking and nonlinear optical resonance. In this work, we numerically investigate the far-field scattering properties of the Si ring-Au split ring nanoantenna (Si R-Au SRN) excited by a tightly focused azimuthally polarized beam (APB) with the finite-difference time-domain (FDTD) method. The results show that the magnetic resonant peak with different width can be deterministically excited in Si ring and Au split ring by tightly focused APB. Due to the plasmon hybridization effect, the two magnetic resonant modes form antibonding mode and bonding mode in the Si R-Au SRN. At the wavelength of λ=1064 nm, the destructive interference between the antibonding and bonding modes of nanostructure results in unidirectional far-field scattering in the transverse plane, which affect dramatically by changes of geometrical parameters. Furthermore, the directional scattering of a dipole source is realized by the designed nanostructure, and its scattering directionality is superior to that excited with APB. Our work provides a flexible way to control the far-field scattering of nano-photon structures. We envision that it could provide an avenue towards the nano-light sources and optical sensors.

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"Silicon cuboid nanoantenna with simultaneous large Purcell factor for electric dipole, magnetic dipole and electric quadrupole emission." Opto-Electronic Advances 5, no. 2 (2022): 210024. http://dx.doi.org/10.29026/oea.2022.210024.

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Habil, Mojtaba Karimi, Carlos J. Zapata–Rodríguez, Mauro Cuevas, and Samad Roshan Entezar. "Multipolar-sensitive engineering of magnetic dipole spontaneous emission with a dielectric nanoresonator antenna." Scientific Reports 11, no. 1 (2021). http://dx.doi.org/10.1038/s41598-021-92322-9.

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AbstractWe propose an axisymmetric silicon nanoresonator with designed tapered angle well for the extraordinary enhancement of the decay rate of magnetic dipole (MD) emitters. Due to the resonant coupling of a MD emitter and the MD mode of the subwavelength resonator, the Purcell factor (PF) can easily reach 500, which is significantly higher than the PF when using a silicon nanosphere of the same size. The PF and the resonance frequency are conveniently tuned through the resonator diameter and the taper angle of the blind hole. When supported by a metallic substrate, further enhancement ($$>10^3$$ > 10 3 ) of the MD spontaneous emission is triggered by an image-induced quadrupolar high-Q mode of the nanoantenna. For the sake of comparison we include a critical analysis of the canonical problem that considers a Si spherical shell. Our results might facilitate a novel strategy for promising realizations of chip-scale nanophotonic applications.

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Negoro, Hidemasa, Hiroshi Sugimoto, and Minoru Fujii. "Circularly Polarized Scattering Radiation From a Silicon Nanosphere." Advanced Optical Materials, October 18, 2023. http://dx.doi.org/10.1002/adom.202301850.

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AbstractA dielectric nanosphere with orthogonal electric dipole (ED) and magnetic dipole (MD) Mie resonances can be a nanoantenna radiating circularly polarized light in specific directions if the amplitudes and the phase relations are properly designed. First, theoretical calculations show that a silicon nanosphere illuminated with a linearly polarized plane wave radiates circularly polarized light at the wavelength in between the ED and MD resonances if the refractive index of a surrounding medium (nm) is ≈1.3; the ellipticity of the scattered light can be >0.99 when nm is in a 1.19–1.35 range. Size‐purified silicon nanospheres suspended in water (nm = 1.33) are then prepared, and the angle‐ and circular‐polarization‐resolved scattering spectra are studied. It is experimentally demonstrated that circularly polarized light is radiated in specific directions under linearly polarized plane wave illumination. The results also show that the wavelength of the radiation of circularly polarized light can be controlled in the whole visible range by controlling the silicon nanosphere diameter in 100–200 nm range.

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Bukharin, Mikhail M., Vladimir Ya Pecherkin, Anar K. Ospanova, et al. "Transverse Kerker effect in all-dielectric spheroidal particles." Scientific Reports 12, no. 1 (2022). http://dx.doi.org/10.1038/s41598-022-11733-4.

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AbstractKerker effect is one of the unique phenomena in modern electrodynamics. Due to overlapping of electric and magnetic dipole moments, all-dielectric particles can be invisible in forward or backward directions. In our paper we propose new conditions between resonantly excited electric dipole and magnetic quadrupole in ceramic high index spheroidal particles for demonstrating transverse Kerker effect. Moreover, we perform proof-of-concept microwave experiment and demonstrate dumbbell radiation pattern with suppressed scattering in both forward and backward directions and enhanced scattering in lateral directions. Our concept is promising for future planar lasers, nonreflected metasurface and laterally excited waveguides and nanoantennas.

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29

Chen, Xiaolin, Weiqing Gao, and Dangyuan Lei. "Giant broadband spin-selective asymmetric transmission and wavefront shaping in transition-metal-dichalcogenide-based chiral metasurfaces." Applied Physics Letters 124, no. 4 (2024). http://dx.doi.org/10.1063/5.0185546.

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Multidimensional spin-selective manipulation of optical waves is crucial for various intriguing applications in modern nanophotonics, such as quantum-information processing and chiral sensing and imaging. In this work, we observed giant broadband asymmetric transmission of circularly polarized waves and spin-preserving reflection, together with near-unity transmission circular dichroism, in a planar chiral metasurface composed of high-index transition-metal-dichalcogenide nanoantennas with large material anisotropy. The perpendicular and parallel electric and magnetic dipole moments excited in the nanoantennas under circularly polarized waves are explored to account for the asymmetric transmission and optical chirality. Combined with the Pancharatnam–Berry phase, we achieved the wavefront manipulation for transmitted circularly polarized waves with an efficiency approaching 91.5% and spin-selective focusing of an incident light via a metasurface metalens. Our work will pave the way for studying the multidimensional manipulation of optical spins through engineering transition-metal-dichalcogenide-based metasurfaces.

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30

Zhou, Yong, Yujie Meng, Wuying Huang, Kuanguo Li, Zhenwei Wang, and Wanxia Huang. "Scattering characteristics of silicon nanoprisms: A theoretical investigation across monomeric to hexameric structures." AIP Advances 14, no. 2 (2024). http://dx.doi.org/10.1063/5.0191112.

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Dielectric nanostructures exhibit intriguing optical properties and outstanding advantages in designing optical nanoantennas and metasurfaces compared to plasmonic nanostructures. This study employs classical electrodynamic methods to comprehensively explore the scattering characteristics of silicon triangular nanoprisms in monomer and oligomer forms. For monomeric nanoprisms, the scattering spectra reveal two distinct and prominent resonance peaks attributed to magnetic dipole (MD) and electric dipole (ED) modes. Reducing interparticle gaps within dimeric structures leads to noticeable blueshifts in MD resonance peaks with stable intensities, in contrast to the nearly constant position and significantly reduced intensities of the ED resonance peaks. A pronounced Fano-like resonance was observed upon transitioning to tetrameric and hexameric configurations, resulting from the coupling between MD and ED modes. A broad resonance peak also emerges in the long-wavelength region due to MD-to-MD coupling. The simulations conducted herein hold significant theoretical implications, advancing our comprehension of the scattering properties of dielectric nanoparticles and contributing valuable insights into fundamental nanophotonics.

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31

Mayoral Astorga, Luis Angel, Masoud Shabaninezhad, Howard Northfield, et al. "Electrically tunable plasmonic metasurface as a matrix of nanoantennas." Nanophotonics, February 27, 2024. http://dx.doi.org/10.1515/nanoph-2023-0796.

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Abstract We report the fabrication and characterization of a plasmonic metasurface comprising electrically-contacted sub-wavelength gold dipole nanoantennas, conformally coated by a thin hafnia film, an indium tin oxide layer and a backside mirror, forming metal–oxide–semiconductor (MOS) capacitors, for use as an electrically-tunable reflectarray or metasurface. By voltage biasing the nanoantennas through metallic connectors and leveraging the carrier refraction effect in the MOS capacitors, our measurements demonstrate phase control in reflection over a range of about 30°, with a constant magnitude of reflection coefficient of 0.5, and the absence of secondary lobes. Comprehensive electromagnetic and quantum carrier models of the structure are developed and are in excellent agreement with the measurements. The metasurface holds promise for use as an optical phased array.

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32

Han, Zhanghua, Fei Ding, Yangjian Cai, and Uriel Levy. "Significantly enhanced second-harmonic generations with all-dielectric antenna array working in the quasi-bound states in the continuum and excited by linearly polarized plane waves." Nanophotonics, December 4, 2020. http://dx.doi.org/10.1515/nanoph-2020-0598.

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AbstractThe recently emerging all-dielectric optical nanoantennas based on high-index semiconductors have proven to be an effective and low-loss alternative to metal-based plasmonic structures for light control and manipulations of light–matter interactions. Nonlinear optical effects have been widely investigated to employ the enhanced interactions between incident light and the dielectrics at the Mie-type resonances, and in particular magnetic dipole resonances, which are supported by the semiconductor. In this paper, we explore the novel phenomenon of bound states in the continuum supported by high-index semiconductor nanostructures. By carefully designing an array of nanodisk structures with an inner air slot as the defect, we show that a novel high quality-factor resonance achieved based on the concept of bound state in the continuum can be easily excited by the simplest linearly polarized plane wave at normal incidence. This resonance further enhances the interactions between light and semiconductors and boosts the nonlinear effects. Using AlGaAs as the nonlinear material, we demonstrate a significant increase in the second-harmonic generation efficiency, up to six orders of magnitude higher than that achieved by magnetic dipole resonances. In particular, a second-harmonic generation efficiency around 10% can be numerically achieved at a moderate incident pump intensity of 5 MW/cm2.

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33

Ho, Jinfa, Zhaogang Dong, Hai Sheng Leong, et al. "Miniaturizing color-sensitive photodetectors via hybrid nanoantennas toward submicrometer dimensions." Science Advances 8, no. 47 (2022). http://dx.doi.org/10.1126/sciadv.add3868.

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Digital camera sensors use color filters on photodiodes to achieve color selectivity. As the color filters and photosensitive silicon layers are separate elements, these sensors suffer from optical cross-talk, which sets limits to the minimum pixel size. Here, we report hybrid silicon-aluminum nanostructures in the extreme limit of zero distance between color filters and sensors. This design could essentially achieve submicrometer pixel dimensions and minimize the optical cross-talk arising from tilt illuminations. The designed hybrid silicon-aluminum nanostructure has dual functionalities. Crucially, it supports a hybrid Mie-plasmon resonance of magnetic dipole to achieve color-selective light absorption, generating electron hole pairs. Simultaneously, the silicon-aluminum interface forms a Schottky barrier for charge separation and photodetection. This design potentially replaces the traditional dye-based filters for camera sensors at ultrahigh pixel densities with advanced functionalities in sensing polarization and directionality, and UV selectivity via interband plasmons of silicon.

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34

Moretti, Gianni Q., Emiliano Cortés, Stefan A. Maier, Andrea V. Bragas, and Gustavo Grinblat. "Engineering gallium phosphide nanostructures for efficient nonlinear photonics and enhanced spectroscopies." Nanophotonics, September 16, 2021. http://dx.doi.org/10.1515/nanoph-2021-0388.

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Abstract Optical resonances arising from quasi-bound states in the continuum (QBICs) have been recently identified in nanostructured dielectrics, showing ultrahigh quality factors accompanied by very large electromagnetic field enhancements. In this work, we design a periodic array of gallium phosphide (GaP) elliptical cylinders supporting, concurrently, three spectrally separated QBIC resonances with in-plane magnetic dipole, out-of-plane magnetic dipole, and electric quadrupole characters. We numerically explore this system for second-harmonic generation and degenerate four-wave mixing, demonstrating giant per unit cell conversion efficiencies of up to ∼ 2 W−1 and ∼ 60 W−2, respectively, when considering realistic introduced asymmetries in the metasurface, compatible with current fabrication limitations. We find that this configuration outperforms by up to more than four orders of magnitude the response of low-Q Mie or anapole resonances in individual GaP nanoantennas with engineered nonlinear mode-matching conditions. Benefiting from the straight-oriented electric field of one of the examined high-Q resonances, we further propose a novel nanocavity design for enhanced spectroscopies by slotting the meta-atoms of the periodic array. We discover that the optical cavity sustains high-intensity fields homogeneously distributed inside the slot, delivering its best performance when the elliptical cylinders are cut from end to end forming a gap, which represents a convenient model for experimental investigations. When placing an electric point dipole inside the added aperture, we find that the metasurface offers ultrahigh radiative enhancements, exceeding the previously reported slotted dielectric nanodisk at the anapole excitation by more than two orders of magnitude.

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35

Hong, Chuchuan, Ikjun Hong, Yuxi Jiang, and Justus C. Ndukaife. "Plasmonic Dielectric Antennas for Hybrid Optical Nanotweezing And Optothermoelectric Manipulation of Single Nanosized Extracellular Vesicles." Advanced Optical Materials, February 8, 2024. http://dx.doi.org/10.1002/adom.202302603.

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AbstractThis study showcases an experimental demonstration of near‐field optical trapping and dynamic manipulation of an individual extracellular vesicle. This is accomplished through the utilization of a plasmonic dielectric nanoantenna designed to support an optical anapole state—a non‐radiating optical state resulting from the destructive interference between electric and toroidal dipoles in the far‐field, leading to robust near‐field enhancement. To further enhance the field intensity associated with the optical anapole state, a plasmonic mirror is incorporated, thereby boosting trapping capabilities. In addition to demonstrating near‐field optical trapping, the study achieves dynamic manipulation of extracellular vesicles by harnessing the thermoelectric effect. This effect is induced in the presence of an ionic surfactant, cetyltrimethylammonium chloride, combined with plasmonic heating. Furthermore, the thermoelectric effect improves trapping stability by a deep trapping potential. In summary, the hybrid plasmonic‐dielectric trapping platform offers a versatile approach for actively transporting, stably trapping, and dynamically manipulating individual extracellular vesicles.

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36

García-Puente, Yalina, Jean-Jacques Laurin, and Raman Kashyap. "Experimental characterization of Spherical Bragg Resonators for electromagnetic emission engineering at microwave frequencies." Scientific Reports 13, no. 1 (2023). http://dx.doi.org/10.1038/s41598-023-47059-y.

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AbstractThis work reports experimental investigation and numerical validation of millimeter-sized Spherical Bragg Resonators (SBRs) fabricated using 3D printing technology. The frequency dependencies of the reflection and transmission coefficients were analyzed, and eigenfrequency values were calculated to examine the density of photonic states in air/PLA-polylactide SBRs, showing the appearance of an eigenmode and an increase in the local density of states in the core of a defect cavity. A decay rate enhancement of $${\sim 10}^{2}$$ ∼ 10 2 was obtained for a dipole placed in the core of the defect SBR. The study also investigated the influence of the source position on the resonator's electromagnetic wave energy. Scattering efficiencies up to order twelve of the multipole electric and magnetic contribution in a 10-layer SBR were calculated to validate the presence of the resonant modes observed in the scattering measurements performed for parallel and perpendicular polarizations. The results demonstrate that SBRs can act as omnidirectional cavities to enhance or inhibit spontaneous emission processes by modifying the density of electromagnetic states compared to free space. This finding highlights the potential of SBRs engineering spontaneous electromagnetic emission processes in various applications, including dielectric nanoantennas, optoelectronics devices, and quantum information across the entire electromagnetic spectrum.

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