Toroidal Dipolar Excitation in Metamaterials Consisting of Metal nanodisks and a Dielectrc Spacer on Metal Substrate

Tang, Chaojun; Wang, Qiugu; Chen, Jing; Yan, Zhendong; Liu, Fanxin; Chen, Naibo; Sui, Chenghua

doi:10.1038/s41598-017-00708-5

Cited by 19 publications

(9 citation statements)

References 45 publications

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“…The results for the Design ② completely coincide with those of the Design ① and therefore are omitted here. Compared to previous toroidal mode studies in metal–dielectric metasurfaces, we observe two different manifestations of the polar toroidal dipole modes at two different frequencies in one trimer‐based all‐dielectric metasurface.…”

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confidence: 81%

“…The intensity distribution of the electric field in the middle plane has a bright hotspot in the center of the cluster and three less bright hotspots on the periphery of the disks. Such distributions are typical for the case of excitation of three magnetic dipole modes whose moments lie in the plane of the structure . The ring‐like arrangement of these moments forms a hybrid state where the magnetic field lines penetrate all three disks in the cluster.…”

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confidence: 94%

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Experimental Observation of Toroidal Dipole Modes in All‐Dielectric Metasurfaces

Sayanskiy

Kupriianov

et al. 2018

Advanced Optical Materials

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helix (a solenoid) bent in a ring (a toroid). The current flowing through the helix cre ates a magnetic field trapped inside the toroid. The resulting moment of such a system is oriented along the axis of revo lution of the toroid, and it is defined as a toroidal moment. If the toroid is rigid, then no magnetic field produced by external sources can act on the toroid as a whole. In the nonideal case, an electro magnetic coupling with such a toroidal moment is possible, although one can expect that this effect should be very weak and hardly measurable. Despite this, the toroidal moment was found to exist in different problems of condensed matter physics, and it was studied in many papers. [2][3][4][5] Similar to the standard multipole expansion [6] related to the electromag netic potentials and sources, the toroidal multipoles originated from the decompo sition of the moment tensor have a dual nature. [7] It means that there appears a distinction between magnetic and electric toroidal multipoles manifested in different flow paths of their polarization cur rents. In particular, a magnetic (polar) toroidal dipole is created by the polarization currents flowing on a surface of a toroid along its meridian (the poloidal direction), whereas an electric (axial) toroidal dipole appears from a ring of polarization cur rents flowing along the toroid (the toroidal direction).The study of toroidal dipole modes has attracted a growing attention due to the specific properties of the toroidal electromagnetic response which differs from more familiar electric and magnetic dipole modes. Herein, toroidal dipole modes generated by metasurfaces composed of trimer clusters of high-index dielectric particles are observed. Both far-field transmission measurements and direct near-field mapping of the electromagnetic fields are performed in microwave experiments, and two distinct types of the toroidal dipole modes are observed in a single geometry of the metasurface design, where the toroidal modes are generated either inside of the three- particle clusters (the so-called intra-cluster toroidal modes) or between the neighboring particles in the clusters (inter-cluster toroidal modes). A transient response of the toroidal dipole modes excited by a pulse is studied in detail.Since the metasurface is composed of simple dielectric disks without the use of any metallic components, the proposed design can be feasibly scalable to both micro-and nanometer-size dielectric structures, and it can be employed in the flat-optics platform for realizing the beams shaping and efficient light-matter interaction for multiple hotspot energy localization, nonlinear frequency conversion, and highly efficient trapping of light. Toroidal Dipole ModesAppearance of a toroidal moment is an intriguing phenomenon in the physics of light-matter interaction, first predicted theo retically in the middle of the last century. It was introduced in the particle physics in the study of the interaction with parity violation for elementary particles and weak electromagnetic f...

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confidence: 94%

Experimental Observation of Toroidal Dipole Modes in All‐Dielectric Metasurfaces

Sayanskiy

Kupriianov

et al. 2018

Advanced Optical Materials

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“…4 a). Such field distributions correspond to the excitation of a magnetic dipole mode [ 82 – 86 ], which steps from the near-field plasmon hybridization between the first Ag nanodisk and the Ag substrate. At the resonance wavelengths of λ 2 , λ 3 , and λ 4 , the electromagnetic fields have the same distribution properties, but are localized in the vicinity of the second, third, and fourth Ag nanodisks with diameters of d 2 , d 3 , and d 4 , respectively.…”

Section: Resultsmentioning

confidence: 99%

Multiband and Broadband Absorption Enhancement of Monolayer Graphene at Optical Frequencies from Multiple Magnetic Dipole Resonances in Metamaterials

et al. 2018

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It is well known that a suspended monolayer graphene has a weak light absorption efficiency of about 2.3% at normal incidence, which is disadvantageous to some applications in optoelectronic devices. In this work, we will numerically study multiband and broadband absorption enhancement of monolayer graphene over the whole visible spectrum, due to multiple magnetic dipole resonances in metamaterials. The unit cell of the metamaterials is composed of a graphene monolayer sandwiched between four Ag nanodisks with different diameters and a SiO2 spacer on an Ag substrate. The near-field plasmon hybridizations between individual Ag nanodisks and the Ag substrate form four independent magnetic dipole modes, which result into multiband absorption enhancement of monolayer graphene at optical frequencies. When the resonance wavelengths of the magnetic dipole modes are tuned to approach one another by changing the diameters of the Ag nanodisks, a broadband absorption enhancement can be achieved. The position of the absorption band in monolayer graphene can be also controlled by varying the thickness of the SiO2 spacer or the distance between the Ag nanodisks. Our designed graphene light absorber may find some potential applications in optoelectronic devices, such as photodetectors.

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“…simple structure which supports magnetic resonances including plasmonic cavities [28], Metal/Dielectric/Metal structure [29] and high refractive index dielectric particle [30] were used to construct toroidal dipole resonators. Considering that all dielectric metasurfaces consisting of high refractive index dielectric particles ire easy to fabricate and has low intrinsic losses, all dielectric metasurfaces that support toroidal dipole have intrigued great attention in research about the response enhancement of toroidal dipole [31,32].…”

Section: Model and Methodsmentioning

confidence: 99%

“…Since thickness of Au substrate is thick enough to prevent light from transmitting, the absorption A of whole structure can be obtained with A = 1 − R with R representing the reflection. Multipolar decomposition of scattered powers is performed in Cartesian coordinate system using Equations ( 1)- (11) to clarify the resonance contribution [29].…”

Section: Model and Methodsmentioning

confidence: 99%

Toroidal Dipole Excitation in Metamaterial Perfect Absorber Consisting of Dielectric Nanodisks Quadrumer Clusters and Spacer on Metal Substrate

2022

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We proposed an infrared narrowband metamaterial perfect absorber (MPA) which is induced by toroidal dipole resonance in a dielectric-metal hybrid system. The MPA is composed of amorphous-silicon (a-Si) nanodisk quadrumer clusters, dielectric spacer, and Au substrate, where the dielectric spacer is inserted between Si disk quadrumer and Au substrate. Near field distribution and multipole decomposition of far-field, scattering powers show that toroidal dipole mode is formed by opposite phase magnetic dipoles in neighboring Si nanodisks. The effects of geometric and material parameters on absorption characteristics were explored. The sensing performance of the MPA was also evaluated. The proposed MPA has potential applications in air sensing applications. Since the nanodisc quadrumer of the MPA retains C4v symmetry, perfect absorption band is polarization independent. Furthermore, the absorption quality factor of the hybrid dielectric-metal hybrid absorber is higher than that of all-metal perfect absorbers, thanks to the low loss feature of the dielectric resonator.

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Toroidal Dipolar Excitation in Metamaterials Consisting of Metal nanodisks and a Dielectrc Spacer on Metal Substrate

Cited by 19 publications

References 45 publications

Experimental Observation of Toroidal Dipole Modes in All‐Dielectric Metasurfaces

Experimental Observation of Toroidal Dipole Modes in All‐Dielectric Metasurfaces

Multiband and Broadband Absorption Enhancement of Monolayer Graphene at Optical Frequencies from Multiple Magnetic Dipole Resonances in Metamaterials

Toroidal Dipole Excitation in Metamaterial Perfect Absorber Consisting of Dielectric Nanodisks Quadrumer Clusters and Spacer on Metal Substrate

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