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-shaped chiral metamaterials
摘要： A highly sensitive refractive index sensor based on the conjugated bilayer-shaped chiral metamaterial is proposed. It is composed of two-shaped structures and a microstrip connecting line. The strong conductive coupling between two-shaped structures can be realized by microstrip connecting line. The chiral metamaterial shows giant circular dichroism (CD) effect, and the CD effect can up to 93.8% and 96.2% at 1.767Thz and 3.008Thz, respectively. The physical origin of the observed CD effect is elucidated through distributions of magnetic and current at resonances. The designed conjugated bilayer-shaped chiral metamaterial as a refractive index sensor can achieve sensitivity of 1.065Thz/RIU and 1.777Thz/RIU, respectively. The effect of structural parameter on the sensitivity and CD spectra is investigated. Through this study we presented the giant CD metamaterial based on conductive coupling and its application potentials for low detection-limit physical and biochemical sensing applications.
关键词： chiral metamaterial,conductive coupling,circular dichroism,resonance,refractive index sensor,metamaterial
更新于2025-09-23 15:22:29
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A Bi-layered Chiral Metamaterial with High-Performance Broadband Asymmetric Transmission of Linearly Polarized Wave
摘要： In this paper, a novel bi-layered chiral metamaterial (CMM) is presented to realize high–efficiency broadband asymmetric transmission (AT) of linearly polarized electromagnetic wave (EM) in the microwave region from 10.1GHz to 15.1GHz. For this purpose, a pair of modified resonators is employed on two sides of a thin dielectric substrate. The simulated and measured results confirm that linearly polarized wave in the form of x-polarized or y-polarized could be nearly converted into the orthogonal polarization after transmission through the introduced prototype which is affirmed by the polarization rotation azimuth angle . The polarization conversion ratio (PCR) is more than 92% at the mentioned frequency range. Full parametric simulation of modified resonators, azimuth rotation angle, and chirality parameter variable with frequency are discussed in detail. In addition, the surface current distributions of the structure have been demonstrated to investigate the physical mechanism of the cross-polarization and corresponding polarization conversion.
关键词： Metamaterials,chiral metamaterial,linearly polarized wave,asymmetric transmission
更新于2025-09-23 15:21:01
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[IEEE 2018 18th Mediterranean Microwave Symposium (MMS) - Istanbul, Turkey (2018.10.31-2018.11.2)] 2018 18th Mediterranean Microwave Symposium (MMS) - Chiral SRR Metasurfaces for Circular Polarisation Conversion
摘要： A circular polarization dual band metamaterial polarization rotator composed of two double split ring resonators rotated 90o with respect to each other is presented. Asymmetric transmission between Txx and Tyy and symmetric transmission between Txy and Tyx has been achieved. The circular polarization is caused by the symmetric transmission between Txy and Tyx. The design has been demonstrated numerically at microwaves frequency. The structure holds promise for ultra-compact polarizing devices for any frequency range given the scalability of the approach.
关键词： Metasurfaces,Circular polarization,Chiral metamaterial,Split Ring Resonators
更新于2025-09-19 17:15:36
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[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) - Terahertz Polarisation Modulator by Electronic Control of Graphene Loaded Chiral Metamaterial Device
摘要： Terahertz (THz) science and technology has experienced tremendous progress in recent years, such as in spectroscopy, imaging, pharmaceutical research [1] and wireless communications. These applications require electrically tuneable devices to modulate the THz properties, including the amplitude, frequency and polarization. The integration of resonant plasmonic/metamaterial devices with graphene, has proved a successful route for the realisation of fast reconfigurable, efficient THz optoelectronic devices [2], via electrical tuning of graphene integrated with plasmonic resonant structures. An active THz modulator is presented based on a chiral metamaterial array containing metallic features, loaded with graphene. The device makes use of an electromagnetically induced transparency analogue produced via the capacitive coupling of bright and dark resonators, the latter actively damped with graphene, exploited for frequency modulation in Ref. [2]. The active area is 1.2 x 1.2 mm, consisting of a 2D chiral metamaterial array comprising 27 x 27 unit cells, shown in Fig. 1a. The resonators were defined using electron-beam lithography, and thermal evaporation of Ti/Au (10/70nm). These features were deposited on top of a 300 nm insulating layer of SiO2 on a boron p-doped silicon substrate. Chemical vapour deposition grown graphene was defined into 3.25 x 3.25 μm2 patches through e-beam lithography.
关键词： chiral metamaterial,electronic control,graphene,polarisation modulator,Terahertz
更新于2025-09-12 10:27:22
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A multi-functional polarization convertor based on chiral metamaterial for terahertz waves
摘要： In this paper, a multi-functional polarization convertor for terahertz (THz) light composed of a bilayer wire-split-ring (WSR) structure chiral metamaterial (CMM) was proposed and investigated numerically. Simulation results indicate that when normal incident light is propagating along the –z axis direction through the proposed CMM structure, the y-polarization is converted to the left- and right-circular polarization (LCP and RCP) at 1.14 THz and 1.34 THz, respectively. Meanwhile, the x-polarization is converted to y-polarization in the frequency range of 2.19-2.47 THz. The further calculation results show that the proposed CMM structure can transmit a nearly pure circular polarization light with a polarization extinction ratio (PER) of over 30 dB and an orthogonal linear polarization light with a polarization conversion ratio (PCR) of over 90%. The mechanism of the polarization conversion properties is illustrated by the simulated electrical field and surface current distribution. Due to its excellent multi-functional polarization conversion properties, the proposed CMM is useful for the development of the integrated THz polarization manipulation devices.
关键词： optical activity,wire-split-ring structure,chiral metamaterial,Circular dichroism
更新于2025-09-10 09:29:36
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Characteristics of Radiation from a Microstrip Antenna on a Substrate Made of a Chiral Metamaterial
摘要： We present a method for electrodynamic analysis of a microstrip antenna on a substrate made of a chiral metamaterial. Singular integral representations of the components of the electric ?eld radiated by such an antenna are presented. A singular integral equation with the Cauchy singularity is obtained, which allows determining the function of the current-density distribution over the antenna surface. The dependences of the magnitude and phase of the electric-?eld components on the coordinates and the radiation patterns of the antenna are calculated. It is shown that the electromagnetic waves radiated by such an antenna have the elliptical polarization.
关键词： electrodynamic analysis,singular integral equation,chiral metamaterial,elliptical polarization,microstrip antenna
更新于2025-09-10 09:29:36
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Metamaterial-Inspired Self Polarizing Dual Band Dual-Orthogonal Circularly Polarized Fabry-Perot Resonator Antennas
摘要： This study presents a Fabry-Perot resonator antenna (FPRA) with dual-band dual-orthogonal circular polarization. The whole FPRA consists of a linearly polarized microstrip patch antenna and a chiral metamaterial superstrate. The linearly polarized microstrip antenna serves as the feed system, while the chiral metamaterial (CMM) superstrate has the function of polarization transformation. The CMM also works as a partial reflective sheet to form an FPRA. Ray-tracing method in the circular base is introduced to describe the mechanism of this type of FPRA. Furthermore, the procedure of controlling the frequency ratio of two bands is discussed as well. An antenna prototype is fabricated to validate the simulated results. In the frequency band from 7.24 GHz to 7.36 GHz, the proposed FPRA produces right-handed circularly polarized wave. However, left-handed circularly polarized wave is achieved when the frequency ranges from7.96 GHz to 8.14 GHz. The realized gains reach 12.98 dBic at 7.28 GHz and 13.25 dBic at 8 GHz, respectively.
关键词： Fabry-Perot resonator antenna,dual-orthogonal circular polarizations,dual-band,chiral metamaterial,high gain,self-polarizing
更新于2025-09-09 09:28:46