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Towards silicon-based metamaterials
摘要： We study periodic lattices of silicon nanorods and introduce the concept of a phase diagram that characterizes a transition between the regimes of photonic crystals and dielectric metamaterials when the lattice spacing and operational wavelength vary. We find the conditions when a hexagonal periodic lattice of silicon nanorods can operate as a metamaterial described by averaged parameters. In general, we reveal that the metamaterial regime can be achieved for dielectric permittivity exceeding the value ε = 14, being commonly available for semiconductors in both visible and near-infrared frequency ranges. Thus, advanced semiconductor technologies can offer a versatile platform for novel designs of all-dielectric Mie-resonant metadevices.
关键词： phase diagram,photonic crystals,dielectric metamaterials,Mie resonances,silicon nanorods
更新于2025-09-23 15:21:21
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Aperiodic order induced enhancement of weak nonlocality in multilayered dielectric metamaterials
摘要： Recent studies on fully dielectric multilayered metamaterials have shown that the negligibly small nonlocal effects (spatial dispersion) typically observed in the limit of deeply subwavelength layers may be significantly enhanced by peculiar boundary effects occurring in certain critical parameter regimes. These phenomena, observed so far in periodic and randomly disordered geometries, are manifested as strong differences between the exact optical response of finite-size metamaterial samples and the prediction from conventional effective-theory-medium models based on mixing formulas. Here, with specific focus on the Thue-Morse geometry, we make a first step toward extending the studies above to the middle ground of aperiodically ordered multilayers, lying in between perfect periodicity and disorder. We show that, also for these geometries, there exist critical parameter ranges that favor the buildup of boundary effects leading to strong enhancement of the (otherwise negligibly weak) nonlocality. However, the underlying mechanisms are fundamentally different from those observed in the periodic case and exhibit typical footprints (e.g., fractal gaps, quasilocalized states) that are distinctive of aperiodic order. The outcomes of our study indicate that aperiodic order plays a key role in the buildup of the aforementioned boundary effects and may also find potential applications to optical sensors, absorbers, and lasers.
关键词： absorbers,optical sensors,lasers,Thue-Morse geometry,aperiodic order,multilayered dielectric metamaterials,nonlocality
更新于2025-09-23 15:21:21
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Coupling Between Silicon Waveguide and Metal-Dielectric-Metal Plasmonic Waveguide with Lens-Funnel Structure
摘要： Various photonic integrated components have been implemented by ultra-thin silicon-on-insulator (SOI) waveguides; therefore, it is desirable to couple ultra-thin SOI waveguides to plasmonic waveguides. In this paper, we present an ultra-thin SOI waveguide to a metal-dielectric-metal plasmonic waveguide based on a lens-funnel structure consisting of truncated Luneburg lens and metallic parabolic funnel. The lens is implemented by varying the guiding layer thickness. The effect of different parameters of the coupler’s geometry is studied using the finite-difference time-domain method. The 1.13-μm-long coupler improves the average coupling efficiency in the C-band from 66.4 to 82.1%. The numerical simulations indicate that the coupling efficiency is higher than 69% in the entire O, E, S, C, L, and U bands of optical communication.
关键词： Luneburg lens,Silicon-on-insulator,All-dielectric metamaterials,Plasmonic waveguide,Optical coupler,Strip waveguide
更新于2025-09-12 10:27:22
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Multipolar-interference-assisted terahertz waveplates via all-dielectric metamaterials
摘要： Polarization control via metamaterials boosts the design of polarimetric devices in the realm of terahertz technology for sensitive detection, bio-imaging, and wireless communication. Here, we propose all-dielectric metamaterials composed of silicon brick arrays that operate as terahertz quarter- and half-waveplates with close to unity transmission. Spherical multipole decomposition calculation indicates that the silicon brick can support multiple Mie-type resonances, such as electric dipole, electric quadrupole, magnetic dipole, and magnetic quadrupole modes. By tailoring the multipolar interference among these resonances, near unity transmission can be obtained with over p phase delay. We experimentally realize dielectric terahertz metamaterials that function as a quarter-wave plate at 0.79 THz and a half-wave plate at 0.91 THz with insertion losses of 0.54 and 1.25 dB, respectively. Such anisotropic dielectric metamaterials promise an exotic approach to engineer the interference among multipolar resonances and reveal the feasibility to realize functional, ef?cient, and compact terahertz meta-devices.
关键词： terahertz,waveplates,silicon brick arrays,all-dielectric metamaterials,multipolar interference
更新于2025-09-10 09:29:36
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Surface enhanced perfect absorption in metamaterials with periodic dielectric nanostrips on silver film
摘要： Integrated dielectric metamaterials with plasmonic structures can cause drastic optical resonances and strengthen the capacity of light absorption. Here, we describe the optical properties of silicon nanoarrays on a thin silver film for extreme light confinement at subwavelength nanoscales. We attain the nearly total absorption in silicon nanostrips, which support magnetic quadruple Mie-type resonances in the visible regions. The Mie resonant field of the dielectric nanostrip engages the screening response of the silver film, resulting in plasmon resonance configuration and thus achieving perfect light absorption in the dielectric nanostrip. Moreover, we can attain similar results in other nanostructures, such as silicon cylinder and rhombus column arrays. Because it can sustain hybridized plasmon modes and magnetic modes, the combined system will benefit the application of solar energy accumulation.
关键词： surface plasmon polaritons,plasmonic structures,dielectric metamaterials,Mie resonances,perfect absorption
更新于2025-09-10 09:29:36