- 标题
- 摘要
- 关键词
- 实验方案
- 产品
-
[IEEE 2018 20th International Conference on Transparent Optical Networks (ICTON) - Bucharest (2018.7.1-2018.7.5)] 2018 20th International Conference on Transparent Optical Networks (ICTON) - Initial Investigation for the Fabrication of Hyperbolic Metamaterials Based on Ultra-Thin Au Layers
摘要： In this paper, we will present the fabrication possibilities developed within our group for obtaining multilayer hyperbolic metamaterials (HMMs). The minimum metallic layer thickness reproducibly obtainable with our current technology is down to 6 nm, while the dielectric layer can be as low as 4 nm. During the talk we will present our approach for obtaining Au layers with better optical properties than the standard techniques. This is achievable by using an adhesion layer whose influence of the metallic properties is lower than the one of the classical Cr or Ti adhesion layers. These organic adhesion layers behave as dielectrics and thus do not contribute more to the metallic response. Since the imaginary part of permittivity of these layers is negligible and the real part is very close to the silica one, their contribution to the behaviour of the HMMs is minimal. The optical properties of Au with organic adhesion layers showing a closer to theory response than Au with metallic adhesion layer as well as a possible explanation for this behaviour will be presented. This technique can be further used to obtain metal-dielectric multi-layers that lead to HMMs behaviour. Both fabrication possibilities and optical characterisation will be shown and discussed during the talk.
关键词： Au layers optical properties,hyperbolic metamaterials,ultra-thin Au layers
更新于2025-09-23 15:22:29
-
Existence Conditions of High-k Modes in Finite Hyperbolic Metamaterials
摘要： The capability to support optical waves with very large wave vectors (high-k) is one of the principle features of hyperbolic metamaterials (HMMs). These waves play the key role in HMM applications such as imaging and lifetime engineering. E?ective medium approximation (EMA) as widely used analytical method to predict HMMs behavior, has shortcomings in calculating high-k modes of practical structures. EMA is applicable to a subwavelength unit cell of implicitly in?nite periodic structures. Using conventional EMA, in the present paper, boundary e?ects and spatial dispersion are taken into consideration to properly compute the high-k modes of ?nite-thickness multilayer HMMs. Applying nonlocal homogenization to stacks of alternating metal-dielectric layers, the corresponding e?ective medium is examined as a high-k waveguide sandwiched between the substrate and an ambient superstrate. The developed theory enables us to recognize two types of bulk waves coined as short-range and long-range propagating modes. Number of such modes as well as their cuto? conditions are quanti?ed for the ?rst time. Validity of the developed theory is veri?ed both numerically by rigorous simulations of the multilayer structures with the transfer matrix method and experimentally by optical characterization of the HMMs in infrared regime.
关键词： subwavelength metal-dielectric multilayers,e?ective medium theory,high-k modes,hyperbolic metamaterials
更新于2025-09-19 17:15:36
-
[IEEE 2019 18th International Conference on Optical Communications and Networks (ICOCN) - Huangshan, China (2019.8.5-2019.8.8)] 2019 18th International Conference on Optical Communications and Networks (ICOCN) - Circularly polarized Airy beam generation with hyperbolic metamaterials at telecom wavelengths
摘要： Metasurfaces have shown great promise for generation of Airy beams, but the available plasmonic/dielectric metasurfaces based circularly polarized Airy beam generators suffer from low efficiency and/or lack of amplitude modulation. Hyperbolic metamaterials (HMMs) have shown great potential to modulate electromagnetic waves with high efficiency in multiple dimensions, including phase, amplitude, and polarization. Here, we propose to use HMM waveguide array to generate circularly polarized Airy beam at telecom wavelengths with both phase and amplitude modulation, and verify the excellent performance with simulation. Our strategy may offer a general approach to generate complicated electromagnetic fields with the requirement of varying amplitudes and phases simultaneously.
关键词： Airy beam,Hyperbolic metamaterials
更新于2025-09-16 10:30:52
-
[IEEE 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Munich, Germany (2019.6.23-2019.6.27)] 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - First Experimental Observation of Photonic Spin Hall Effect in Hyperbolic Metamaterials at Visible Wavelengths
摘要： The photonic spin Hall effect [1] or spin Hall effect of light [2] is the photonic analog of the spin Hall effect occurring with charge carriers in solid-state systems. Typically, this phenomenon takes place when a light beam refracts at an air-glass interface, or when it is projected onto an oblique plane, the latter effect being known as the geometric spin Hall effect of light [3]. In general, the photonic spin Hall effect leads to a polarization dependent transverse shift of a light peak intensity [3,4]. An example of the latter effect is the transverse Imbert–Federov beam shift [3], which happens for paraxial beams reflected or refracted at a sharp inhomogeneity of an isotropic optical interface. Potential applications of the photonic spin Hall effect in spin-dependent beam splitters, optical diodes [1], and surface sensors are considered in various fields in photonics, such as nanophotonics, plasmonics, metamaterials, topological optics, and quantum optics [1,2]. Here we experimentally demonstrate extreme angle sensitivity and enhancement of the spin Hall effect of light in hyperbolic metamaterials (HMMs) in the visible regime [5]. The effect is shown in transmission through a 176 nm thick HMM composed of alternating Au/Alumina layers, as illustrated in Fig.1 (a). The transverse beam shift in our HMM setting is very sensitive to the angle of incidence, drastically changing from almost no beam shift to a few hundred microns by the change of ≈0.003 rad (≈0.17°) in the incident angle, as illustrated in Fig. 1 (b). The experimental results are in extremely good agreement with the simulated values based on a theory developed by Tang et al. [6] with realistic parameters of fabricated HMMs, and taking into account beam divergence and setup errors. The large photonic spin Hall enhancement in a such thin structure and extreme angular sensitivity can be exploited in compact spin Hall devices which enable the manipulation of photons by polarization, with direct applications in quantum optics and communications.
关键词： optical diodes,photonic spin Hall effect,hyperbolic metamaterials,spin-dependent beam splitters,surface sensors,visible wavelengths
更新于2025-09-11 14:15:04
-
[IEEE 2018 12th International Congress on Artificial Materials for Novel Wave Phenomena (Metamaterials) - Espoo, Finland (2018.8.27-2018.9.1)] 2018 12th International Congress on Artificial Materials for Novel Wave Phenomena (Metamaterials) - Reduction of the beam-coupling impedance in accelerating structures using metamaterial-based absorbers
摘要： Resistive-wall impedance constitutes a significant percentage of the total beam-coupling impedance budget of an accelerator. Under extreme conditions, like large power handling and ultra-high vacuum, metamaterial-based absorbers can represent a valid alternative to other approaches for impedance mitigation in specific accelerator components, like resonant (parasitic) cavities or collimators operating along the beam line. We design sub-wavelength 2D metallic resonant structures based on split rings or on 3D hyperbolic tapered waveguide arrays that can be employed as mode dampers in accelerating structures. A number of prototypes are fabricated and then measured in a “test model” pillbox cavity.
关键词： accelerators,hyperbolic metamaterials,metamaterials,beam-coupling impedance,split-ring resonators
更新于2025-09-10 09:29:36
-
Redshift gaps in one-dimensional photonic crystals containing hyperbolic metamaterials
摘要： In conventional all-dielectric one-dimensional photonic crystals (1DPCs), photonic gaps will shift toward short wavelengths (blueshift) as the incident angle increases for both transverse magnetic (TM) and transverse electric (TE) polarizations. We theoretically and experimentally achieve redshift gaps in 1DPCs composed of alternative hyperbolic metamaterials (HMMs) and dielectrics for TM polarization based on the anomalous wavevector dispersion of HMMs. The HMM is mimicked by layered titanium dioxide and silver with a subwavelength unit cell. However, the gaps remain to be blue-shifted for TE polarization. Therefore, the edges of such gaps can be utilized for high-e?ciency wide-angle polarization selection. We achieve e?cient polarization selection for incident angles ranging from 50 o to 80o at the wavelength of 365 nm.
关键词： one-dimensional photonic crystals,redshift gaps,polarization selection,hyperbolic metamaterials
更新于2025-09-04 15:30:14