- 标题
- 摘要
- 关键词
- 实验方案
- 产品
-
Broadband terahertz metamaterial absorber enabled by using high-loss dielectric materials
摘要： Metamaterial absorbers consisted of two metallic layers separated by low-loss dielectric materials have been extensively presented and studied. However, these absorbers using low-loss dielectric materials usually exhibit narrow bandwidth, which are not conductive to the practical applications. Here, we demonstrate a novel terahertz meta-device that can obviously widen the absorption bandwidth of metamaterial absorber. This meta-device is composed of a high-loss dielectric material sandwiched by a metallic strip and an opaque metallic mirror. Absorption of greater than 80% of the meta-device can cover a continuous frequency range of 2.43 THz, and its relative absorption bandwidth can reach 89.17%. These two indexes are both much larger than those of previous absorption devices using low-loss dielectric materials. Physical mechanism of the meta-device originates from the superposition of two different resonant modes. More importantly, the variation of meta-device parameters can provide considerable degree of freedom to regulate the absorption bandwidth and relative absorption bandwidth of the device.
关键词： broadband absorption,metamaterials,perfect absorber,high-loss dielectric material
更新于2025-09-19 17:13:59
-
[IEEE 2019 IEEE 16th International Conference on Group IV Photonics (GFP) - Singapore, Singapore (2019.8.28-2019.8.30)] 2019 IEEE 16th International Conference on Group IV Photonics (GFP) - Sub-Decibel Off-Chip Fiber Couplers Based on L-Shaped Waveguides and Subwavelength Grating Metamaterials
摘要： Uniform grating couplers based on versatile L-shaped waveguides are experimentally demonstrated, with coupling loss of -2.7 dB and back-reflections of -20 dB. Apodized couplers with subwavelength-grating metamaterials predict improved fiber-chip coupling down to -0.46 dB within device layouts compatible with lithographic technologies available in nanophotonic foundries.
关键词： silicon-on-insulator,sub-wavelength grating metamaterials,deep-ultraviolet technology,silicon nanophotonics,grating couplers,mass-scale production
更新于2025-09-16 10:30:52
-
Tunable Triple-Band Plasmonically Induced Transparency Effects Based on Double π-Shaped Metamaterial Resonators
摘要： Tunable triple-peaks with the transmission intensity of more than 90% plasmonically induced transparency metamaterial resonator based on nested double π-shaped metallic structure is proposed at the terahertz frequency region, which is consisted of three sets of gold nanorods with different sizes placed on a dielectric substrate of SiO2. The coupling effect of localized electric field between different parts of the proposed structure can be used to explain the physical mechanism of three transparent windows. The finite-difference time-domain (FDTD) is used to study the spectral properties of the proposed structure, and the influence of the size of the nanorods and the relative distance between them on the spectral characteristics are also discussed. It can be seen that some obvious shift phenomena occur in the spectra with the change of these nanorods. These results indicate that the proposed structure opens up new avenues in many related applications, especially for multi-channel filters, optical switches, and sensors.
关键词： Double π-shaped resonator,Plasmonically induced transparency,Metamaterials,Terahertz
更新于2025-09-16 10:30:52
-
[IEEE 2019 IEEE 16th International Conference on Group IV Photonics (GFP) - Singapore, Singapore (2019.8.28-2019.8.30)] 2019 IEEE 16th International Conference on Group IV Photonics (GFP) - Sub-Decibel Off-Chip Fiber Couplers Based on Z-Shaped Waveguides and Subwavelength Grating Metamaterials
摘要： Uniform grating couplers based on versatile L-shaped waveguides are experimentally demonstrated, with coupling loss of -2.7 dB and back-reflections of -20 dB. Apodized couplers with subwavelength-grating metamaterials predict improved fiber-chip coupling down to -0.46 dB within device layouts compatible with lithographic technologies available in nanophotonic foundries.
关键词： deep-ultraviolet technology,mass-scale production,sub-wavelength grating metamaterials,silicon-on-insulator,silicon nanophotonics,grating couplers
更新于2025-09-16 10:30:52
-
The influence of PT-symmetric degree on extraordinary optical properties of one-dimensional periodic optical waveguide networks
摘要： In this paper, we design two kinds of one-dimensional (1D) equal-length two-segment-connected periodic triangular optical waveguide networks with different PT-symmetric degrees, one-dimensional PT-symmetric triangular optical waveguide network (1D PT-TOWN) and one-dimensional non-PT-symmetric triangular optical waveguide network (1D nPT-TOWN). It is found that no matter whether the network is PT-symmetric or non-PT-symmetric, as long as a PT-symmetric unit exists, both gain and loss photonic nonpropagation modes will be created and their frequencies are all the same. Consequently, ultrastrong extraordinary transmissions can be generated by two networks, which can arrive at 62.210× and 48.710× respectively. However, because the PT-symmetric degree of the former is higher than the latter, the transmission of the former is two orders of magnitude larger than the latter. Therefore, The PT-symmetric degree influences seriously on the photonic modes distribution and transmission of the network. Our research may deepen people's understanding of PT symmetry, which has potential application to the design of high-efficiency photon energy storage device, optical switches, optical amplifiers, and so on.
关键词： waveguides,optical materials,metamaterials
更新于2025-09-16 10:30:52
-
Tunable infrared asymmetric light transmission and absorption via graphene-hBN metamaterials
摘要： We theoretically prove in this paper that using planar multilayer graphene-hexagonal boron nitride (hBN) metamaterials (GhMMs) can yield ultrabroadband and high-contrast asymmetric transmission (AT) and asymmetric absorption (AA) of light. The AA and AT features are obtained in the far-infrared (FIR) and mid-infrared (MIR) regions for normally incident light with transverse magnetic polarization. Here, the GhMMs are integrated with two asymmetric gratings of Ge and are composed of alternating multilayers of graphene (11 multi-layers) and hBN layers (10 layers). Moreover, the total subwavelength thickness of the hybrid structures is about 3 μm, being less than half of the free-space wavelength up to nearly 50 THz. This approach—which is similar to the one introduced by Xu and Lezec [Nat. Commun. 5, 4141 (2014)] for a passive hyperbolic metamaterial operating in the visible range—is based on the excitation of high-β modes of the GhMM with di?erent transmission characteristics. In addition to being ultrabroadband and high-contrast, AT and AA features of the proposed GhMMs can be actively tuned by varying the chemical potential of graphene. Furthermore, it is shown that an on-o? switching of AT factor at FIR and selective tunability at MIR frequencies can be obtained via varying μ. Due to its subwavelength and planar con?guration and active operation, these multilayer graphene-hBN metamaterials with AT and AA characteristics hold promise for integration with compact optical systems operating in the MIR and FIR ranges and are suitable for applications such as optical diodes, sensors, and thermal emitters.
关键词： asymmetric absorption,asymmetric transmission,mid-infrared,graphene-hBN metamaterials,tunable optical properties,far-infrared
更新于2025-09-16 10:30:52
-
Investigation of Phonon Scattering on the Tunable Mechanisms of Terahertz Graphene Metamaterials
摘要： The in?uences of di?erent kinds of phonon scatterings (i.e., acoustic (AC) phonon, impurity, and longitudinal optical (LO) phonon scatterings) on the tunable propagation properties of graphene metamaterials structures have been investigated, also including the e?ects of graphene pattern structures, Fermi levels, and operation frequencies. The results manifested that, at room temperature, AC phonon scattering dominated, while with the increase in temperature, the LO phonon scattering increased signi?cantly and played a dominate role if temperature goes beyond 600 K. Due to the phonon scatterings, the resonant properties of the graphene metamaterial structure indicated an optimum value (about 0.5–0.8 eV) with the increase in Fermi level, which were di?erent from the existing results. The results are very helpful to understand the tunable mechanisms of graphene functional devices, sensors, modulators, and antennas.
关键词： terahertz,metamaterials,phonon scatterings,graphene
更新于2025-09-16 10:30:52
-
[IEEE 2019 21st International Conference on Transparent Optical Networks (ICTON) - Angers, France (2019.7.9-2019.7.13)] 2019 21st International Conference on Transparent Optical Networks (ICTON) - Towards Efficient Nonlinear Plasmonic Metasurfaces
摘要： Nonlinear processes are important in many fields of photonics ranging from biomedical imaging to ultrashort pulse generation. Progress in nanophotonics and metamaterials has created a growing demand for nanoscale nonlinear optical components. However, it is difficult to answer this demand by using traditional materials motivating the search for alternatives approaches. Nonlinear plasmonics has emerged as a viable solution for enabling efficient and nanoscale nonlinear optics. Despite steady progress, so far achieved conversion efficiencies of metamaterials have not yet rivalled conventional nonlinear materials. Here, we discuss our recent progress in development of efficient nonlinear plasmonic metamaterials. Focus is on metasurfaces utilizing collective responses known as surface lattice resonances, which can be used to dramatically boost nonlinear responses of metasurfaces.
关键词： nonlinear metamaterials,surface lattice resonances,metasurfaces,frequency conversion
更新于2025-09-16 10:30:52
-
Characterizing Optical Fiber Transmission Matrices Using Metasurface Reflector Stacks for Lensless Imaging without Distal Access
摘要： The ability to retrieve image data through hair-thin optical fibers promises to open up new applications in a range of fields, from biomedical imaging to industrial inspection. Unfortunately, small changes in mechanical deformation and temperature can completely scramble optical information, distorting any resulting images. Correction of these dynamic changes requires measurement of the fiber transmission matrix (TM) in situ immediately before imaging, which typically requires access to both the proximal and distal facets of the fiber simultaneously. As a result, TM calibration is not feasible during most realistic usage scenarios without compromising the thin form factor with bulky distal optics. Here, we introduce a new approach to determine the TM of multimode or multicore optical fibers in a reflection-mode configuration, without requiring access to the distal facet. We propose introducing a thin stack of structured metasurface reflectors at the distal facet of the fiber, to introduce wavelength-dependent, spatially heterogeneous reflectance profiles. We derive a first-order fiber model that compensates these wavelength-dependent changes in the fiber TM and show that, consequently, the reflected data at three wavelengths can be used to unambiguously reconstruct the full TM by an iterative optimization algorithm. Unlike previous approaches, our method does not require the fiber matrix to be unitary, making it applicable to physically realistic fiber systems that have non-negligible power loss. We demonstrate TM reconstruction and imaging first using simulated nonunitary fibers and noisy reflection matrices, then using larger experimentally measured TMs of a densely packed multicore fiber (MCF), and finally using experimentally measured multiwavelength TMs recorded from a step-index multimode fiber (MMF). Parallelization of multiwavelength in situ measurements could enable experimental characterization times comparable with state-of-the-art transmission-mode fiber TM experiments. Our findings pave the way for online TM calibration in situ in hair-thin optical fibers.
关键词： Optics,Metamaterials
更新于2025-09-16 10:30:52
-
[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