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In view of the problem of heavy weight of the low-frequency band metamaterial absorber, the weight of the metamaterial absorber is mainly concentrated in the medium dielectric substrate. Different from the previous metamaterial absorbers based on continuous dielectric substrate, a new lightweight metamaterial absorber based on discontinuous dielectric medium is proposed and verified in the L-band (1–2 GHz). Compared with metamaterial absorber based on the continuous dielectric substrate, the weight of the metamaterial absorber designed based on discontinuous media is reduced by 42.58%. The dual-peak reflection losses of −17.29 dB and −15.99 dB are obtained at 1.23 GHz and 1.72 GHz, respectively. Our work provides a new method for constructing light dual-peak metamaterial absorbers in the L-band. [ABSTRACT FROM AUTHOR]

A novel single-layer graphene-based structure is designed in this article. This structure consists of two graphene strips and two graphene blocks. The components of this structure generate two bright modes and one dark mode in the terahertz region, and these three modes undergo destructive interference, leading to the phenomenon of double plasmonic induced transparency. The graphene of this structure has continuity, and the Fermi level can be adjusted by adjusting the bias voltage applied to the structure. Compared with those discontinuous structures, it is easier to achieve tuning function. The structure uses the finite-difference time-domain for data simulation, uses the coupled mode theory for theoretic calculation, and compares the transmission spectra obtained by the two methods. Through observation, it can be found that the frequency positions of the peaks and dips of the simulated transmission spectrum increase with the increase of the Fermi level, showing a perfect linear relationship, which indicates that this structure has great prospects in the modulator. In addition, the structure has achieved good results in the slow light effect, and after measurement, the peak values of group index and group delay can reach up to 380 and 0.241 ps, respectively. By utilizing these advantages, this structure can provide more possibilities for the development and research of slow light fields. [ABSTRACT FROM AUTHOR]

The complementary-modeled Rossler chaotic metamaterial (CRCM) with FR-4 dielectric layer is proposed to design metamaterial absorber with multi-resonance peaks. Under "master-slave" boundary condition in high-frequency structure simulator (HFSS) software, the electric field between adjacent boundaries presents phase difference which can simulate an infinite array. The research results show that the CRCM demonstrates multi-resonant peaks from 4 GHz to 10 GHz, and the area of metal patterned-layer can obviously regulate the resonant peaks. The CRCM presents a linear polarization conversion peak around 5.80 GHz, its polarization conversion ratio (PCR) is near 100%. The PCR is also larger than 80% from 5.56 GHz to 5.95 GHz. Through the surface current density distribution and the comparison between the CRCM and complementary-modeled double ring metamaterial (CDRM), the main factors generating polarization conversion are the asymmetry of metal pattern layer and magnetic resonance caused by reverse current. The CRCM also has two strong absorption peaks located at 6.31 and 9.37 GHz, respectively. Dielectric loss and ohmic loss are the main microwave loss mechanisms proved by volume and surface power loss density distribution. The resonant frequencies derived from L – C resonant circuit are well consistent with the simulation data and measurement results. [ABSTRACT FROM AUTHOR]

A metal-dielectric-metal (MDM) sandwich metamaterial perfect absorber (MPA) with magnetic nickel metal has been designed. An optimal absorption of 99.28% at 404 MHz is achieved for MPA with thickness of 5.54 mm. Resonant absorption is demonstrated to be main mechanism according to analyses on surface current distributions and electromagnetic field distributions. Furthermore, the electromagnetic energy is mainly dissipated in magnetic metal with magnetic loss proportion of 55.43% by comparatively analyzing the wave-absorbing performance of using magnetic metal, non-magnetic metal and perfect electric conductor (PEC) as metallic layers. These results would provide a guidance for the design of quasi-microwave absorbing/shielding materials. [ABSTRACT FROM AUTHOR]

• We have designed a terahertz metamaterial structure based on periodic continuous patterned graphene monolayer. • By increasing the carrier mobility from 0.4 to 3.4 m2/(V⋅s), the group index can be elevated from 80 to 430, that is, the group index increases by a factor of 5.375. • The numerical results demonstrate a strong consistency between the data of coupled-mode theory and the results of actual simulation experiments. We present a straightforward metamaterial structure based on a graphene monolayer, which comprises a single graphene block and two graphene strips. This innovative design enables plasma-induced transparency (PIT) phenomenal generation by harnessing the interplay between bright and dark modes. To elucidate this phenomenon, we conduct comprehensive theoretical calculations that corroborate the findings of simulate results from finite difference time domain (FDTD). Furthermore, we explore the PIT phenomenon across various Fermi energy levels while also investigating the associated slow light effect in relation to the structural parameter, Fermi energy level, and carrier mobility. By increasing the carrier mobility from 0.4 to 3.4 m2/(V⋅s), the group index can be elevated from 80 to 430. Consequently, this graphene-based metamaterial holds promise for inspiring novel approaches to the design of modulators, optical switches, and devices for manipulating slow light. [ABSTRACT FROM AUTHOR]

An optimized NiZn ferrite absorber for the whole P-band (230 -1000 MHz) is proposed by inserting cross-shaped metamaterial. Effective absorption bandwidth below − 10 dB for the composite absorber covers the frequency range 210 MHz-1000 MHz. Electromagnetic wave attenuation mechanisms are revealed by surface current distribution and power loss density distribution. The increased absorption bandwidth of the composite absorber is attributed to the overlap effect of three absorption peaks originated from the multilayer cross-shaped metamaterial absorbers. Results indicate that the proposed composite absorber can be utilized in the P-band with relatively less thickness compared to the traditional NiZn ferrite absorber. [ABSTRACT FROM AUTHOR]

Development of microwave absorption technology triggers higher requirements for the multi-function of microwave absorbing materials. An optically transparent and mechanically stretchable wave-absorbing metamaterial based on fractal structure has been proposed numerically and experimentally in the microwave low frequency range. It is designed to possess two spectrally overlapped resonances located at 4.42 GHz and 7.02 GHz, which originate from the first-order cross resonance and the second-order cross resonance, respectively. Microwave absorbing mechanisms are elaborated by normalized impedance, surface current and power loss density. Moreover, the optical transmittance of the designed wave-absorbing metamaterial is higher than 70 % in the visible region. By stretching the absorber, the frequencies of two resonant peaks occur remarkable red shift with a adjustable frequency band range of 0.64 GHz. The corresponding relationship between the variation of substrate thickness and square resistance and the shift of peak absorption frequencies is discussed. Ultimately, the wave-absorbing performance of the proposed wave-absorbing metamaterial are illustrated at different incident angles for both TE and TM waves. Research results could provide and enrich instructive guidances for realizing optically transparent and mechanically stretchable metamaterial absorber. • The designed metamaterial absorber based on fractal structure was successfully prepared. • The proposed metamaterial absorber possesses strong microwave absorption and high optical transmittance simultaneously in the low frequency range. • Reflection loss of the proposed metamaterial absorber is better than − 10 dB from 3.86 GHz to 8.04 GHz. • Optical transmittance of the designed wave-absorbing metamaterial is higher than 70 % in the visible region. [ABSTRACT FROM AUTHOR]