A planar all-dielectric metamaterial made of a double-periodic lattice whose unit cell consists of a single subwavelength dielectric particle having the form of a disk possessing a penetrating hole is considered. The resonant states in the transmitted spectra of the metamaterial are identified considering modes inherent to the individual cylindrical dielectric resonator. A correlation between the asymmetry in the particle's geometry, which arises from the off-centered displacement of the hole and the formation of the Mie-type and trapped modes, is established. The advantages of using a coaxial-sector notch instead of a round hole for the trapped mode excitation are explained.
In order to construct a dielectric analog of spaser, we study theoretically and experimentally several configurations of cluster-based unit cells for an all-dielectric metasurface characterized by resonant conditions of the trapped mode excitation. Excitation of the trapped mode is realized either by specific displacement of particles in the cluster, or by perturbation of the equidistantly spaced particles by off-centered round holes or coaxial-sector notches. It turns out that the latter approach is more advantageous for enhancement of electric near-field with homogeneous distribution in-plane of the structure and its strong localization outside the high-refractive-index dielectric particles. This feature opens prospects for realization of highly desirable subwavelength flat lasing structures based on strong near-field interaction with substances exhibiting pronounced nonlinear characteristics and properties of gain media.Considerable interest in the study of metamaterials is due to the prospects of their use in practical devices. 1 Metamaterials can be a suitable platform for many optical systems, such as sensors 2 and perfect absorbers. 3 They allow one to enhance quantum dots luminescence, 4,5 realize optical switching 6,7 and other related operations 8 when combined with optically active and nonlinear substances. 9,10 In the latter case, thin planar metamaterials (metasurfaces) are of special interest, due to their higher workability. 11,12 In particular, it is proposed to combine metasurfaces with optically active materials to obtain parametric gain systems and develop amplifying or lasing devices 13 (e.g. spaser -Surface Plasmon Amplification by Stimulated Emission of Radiation 14,15 ). In a metasurface-based spaser a regular array of subwavelength metallic resonators is supported by a slab of gain medium containing quantum dots. A special type of symmetry-broken resonators is chosen to ensure excitation of a high-qualityfactor (high-Q) trapped mode with reduced radiative losses. 16,17 The collective plasmonic oscillations in such resonators lead to the emission of spatially and temporarily coherent light in the direction normal to the metasurface array. The spaser system is very thin and compact and benefits from the strong electric field localization near the surface associated with plasmons. Nevertheless, although the concept of the metasurface-based spaser is well developed, its practical implementation is difficult due to requirement of high pumping power, which adversely affects the system. It arises from excessive heat a) Electronic mail: tvr@rian.kharkov.ua and tvr@jlu.edu.cn losses inherent in plasmonic nanostructures in infrared and visible parts of spectrum. Moreover, asymmetric plasmonic particles composing the metasurface typically have a quite complicated form, so it is difficult to fabricate them on the nanoscale.All-dielectric metasurfaces can overcome abovementioned drawbacks of plasmonic structures while being simple in manufacturing. [18][19][20] The resonant behavior of light in high-re...
Resonant optical antennas supporting plasmon polaritons (SPPs)—collective excitations of electrons coupled to electromagnetic fields in a medium—are relevant to sensing, photovoltaics, and light‐emitting devices, among others. Due to the SPP dispersion, a conventional antenna of fixed geometry, exhibiting a narrow SPP resonance, cannot simultaneously operate in two different spectral bands. In contrast, here it is demonstrated that in metallic disks, separated by a nanometric spacer, the hybridized antibonding SPP mode stays in the visible range, while the bonding one can be pushed down to the mid‐infrared range. Such an SPP dimer can sense two materials of nanoscale volumes, whose fingerprint central frequencies differ by a factor of 5. Additionally, the mid‐infrared SPP resonance can be tuned by employing a phase‐change material (VO2) as a spacer. The dielectric constant of the phase‐change material is controlled by heating the material at the frequency of the antibonding optical mode. These findings open the door to a new class of optoelectronic devices able to operate in significantly different frequency ranges in the linear regime, and with the same polarization of the illuminating wave.
An uncommon double-ray scenario of light resonant scattering by a periodic metasurface is proposed to provide strong non-specular reflection. The metasurface is constracted as an array of silicon nanodisks placed on thin silica-onmetal substrate. A low-lossy non-specular resonant reflection for any direction and any polarization of incident wave is revealed by a numerical simulation of light scattering. The conditions for the implementation of an autocollimation scheme of scattering and the observation of non-specular reflected ray that does not lie in the incidence plane are worked out. It is shown that the change of dielectric substrate thickness may be applied to set the width of frequency band of non-specular reflection. The light intensity related to the specular and non-specular reflected ray can be controlled by changing the angle of incidence or by the polarization of incident wave.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.