Tunable Dual-band Metamaterial Absorber Research Articles

Mechanically tunable dual-band metamaterial absorber at ultra-high frequency

We numerically demonstrated a dual-band metamaterial absorber (MPA) operating in low frequency range based on a flexible polyimide substrate. For the flat configuration, two absorption peaks are obtained at 450 MHz and 1.47 GHz with absorption over 90%. The ratios of the periodicity of unit cells and thickness to the longest absorption wavelength are 1/12 and 1/114, respectively. Especially, our MPA is insensitive with polarization and stable with the oblique incidence angle of incoming electromagnetic waves. The proposed MPA maintains an absorption over 90% when incident angle is increased up to 60o. Furthermore, since structure is wrapped and attached to cylindered surfaces (the varying radii from 200 to 500 mm), new absorption peaks can be obtained at higher frequency range. For both flat and curvature states, the absorption mechanism is explained by the magnetic resonance and the perfect impedance matching phenomena.

Tunable dual-band metamaterial absorber in the infrared range based on split-ring-groove array.

In this paper, we present a tunable dual-band perfect metamaterial absorber working in the infrared band by integrating a metallic split-ring-groove resonator array with a liquid crystal (LC) layer atop a metal substrate. By varying the height of the central nanodisks, the absorptivity of the dual-band absorption peaks can be simultaneously adjusted. The dual-band resonance frequencies of the proposed absorber exhibit continuous tunability by adjusting the refractive index of the LC, which can be controlled by applying external voltage. The mechanism of the perfect absorption is attributed to the gap plasmonic resonance coupling regime. The presented absorber exhibits good tolerance to incidence angles up to 60° and shows polarization dependent performance, which may offer promising applications in sensing, modulator, and optical absorption switching in the infrared regime.

Tunable dual-band metamaterial absorber at deep-subwavelength scale

A tunable dual-band metamaterial absorber composed of a gold square ring and a metal film separated by a strontium titanate dielectric is investigated. Two resonance peaks at frequencies 0.162 THz and 0.329 THz with over 99% absorbance are realized at room temperature. The maximum ratio between the lattice constant and the resonance wavelength is approximately 8.2%, which is much smaller than that of the formerly reported absorber. When the temperature changes from 150 K to 350 K, the two resonance absorption peaks at approximately 66.2% and 67.8% of the modulation depths are obtained. The effective impedance method and the LC equivalent circuit modelling are used to analyze the absorption mechanism of the proposed absorber. The proposed absorber is not affected by the change in polarization angles at normal incidence. The proposed structure adopts a single patterned square ring, which can be manufactured easily, and extended to other frequencies in applications such as biosensors, monitoring and imaging.

Modulation of the absorption properties of a dual band metamaterial based on VO2 thin films

A temperature tunable dual band metamaterial absorber is designed and fabricated. An absorption peak at 1.08 THz is derived from the localized surface plasmon (LSP) mode, while another absorption peak at 1.75 THz is derived from the cavity resonance mode. When different gases are applied to the sample surface, the amplitude and the resonance frequency of the absorption peak at 1.08 THz are modulated. When different liquids are applied to the sample surface, the amplitude of the absorption peak at 1.08 THz is reduced and the resonance frequency is shifted to lower frequencies. The original resonance properties of the absorption peak at 1.08 THz are basically preserved during the measured temperature increase and decrease. The absorption peak at 1.75 THz is sensitive to changes in temperature. The absorption amplitude and resonance frequency are both controlled in the measured temperature increase and decrease.

Temperature-insensitive and separately tunable dual-band metamaterial absorber based on graphene at mid-infrared regions

Abstract The temperature-insensitive and separately tunable dual-band metamaterial absorber (MA) based on graphene are investigated at mid-infrared regions. The design scheme is shown in the way of placing two gammadion-shaped metals with different sizes on the corresponding graphene interdigitated finger sets. Numerical results show that the position of two absorption peaks is separately tuned by manipulating the Fermi energy of corresponding graphene interdigitated finger. Different from the conventional tunable dual-band MAs, the dual-band absorption intensities remain strong over a wide ambient temperature ranging up to 800 K. Further results reveal that the dual-band strong absorption can be also maintained even though the top patterned metals are filleted. The separately tunable MA with the above-mentioned features is of potential interest in some areas, such as frequency selective detectors for sensing applications and temperature-insensitive infrared absorbers.

Design of a concise and dual-band tunable metamaterial absorber

We theoretically present a concise and tunable dual-band metamaterial absorber composed of a typical metal-dielectric-metal structure in the terahertz regime. The dual-band absorption originates from two different resonance modes induced in one square ring, which is different from the common dual-band absorber composed of a super unit with several different-sized structures. The proposed absorber can realize dynamic tunability through changing the permittivity of the dielectric layer by applying different temperatures. Other good performances, such as a wide incident angle and polarization insensitivity, are also available for the proposed absorber. Such a metamaterial absorber is a promising candidate for terahertz imaging and detection.

Graphene-Based Tunable Polarization Insensitive Dual-Band Metamaterial Absorber at Mid-Infrared Frequencies**Supported by the National Natural Science Foundation of China under Grant No 61001018, the Natural Science Foundation of Shandong Province under Grant No ZR2012FM011, the Shandong-Provincial Higher Educational Science and Technology Program under Grant No J11LG20, the Qingdao City Innovative Leading Talent Plan under Grant No 13-CX-25, the THz Science and

A graphene-based tunable dual-band metamaterial absorber which is polarization insensitive is numerically proposed at mid-infrared frequencies. In numerical simulation the metamaterial absorber exhibits two absorption peaks at the resonance wavelengths of 6.246 μm and 6.837 μm when the Fermi level of graphene is fixed at 0.6 eV. Absorption spectra at different Fermi levels of graphene are displayed and tuning functions are discussed in detail. Both the resonance wavelengths of the absorber blue shift with the increase in Fermi level of graphene. Moreover, the surface current distributions on the gold resonator and ground plane at the two resonance wavelengths are simulated to deeply understand the physical mechanism of resonance absorption.

Electromagnetic energy harvesting application based on tunable perfect metamaterial absorber

This paper introduces an electromagnetic (EM) energy harvesting application based on tunable dual-band metamaterial absorber (MA) which includes a ring resonator with gap loaded varactor diode that operates in the microwave frequency regime. Although the suggested tunable structure has a very simple geometry, it provides perfect absorption of 99.91 and 84.79% for both frequencies of 5.01 and 4.79 GHz, respectively. It is concluded from the numerical analysis that it can be obtained higher voltage value on varactor diode when the metal plate is added on the structure, to achieve perfect absorber with EM energy harvesting. We also present a numerical analysis in order to explain physical interpretation of the harvesting mechanism in detail. A sensor application of the proposed structure is introduced in order to show an additional feature of the model. Moreover, the proposed tunable model is also suitable for a wide variety of microwave EM energy harvesting applications such as power transfer to any component, wireless power transmitter etc.

A new tunable dual-band metamaterial absorber with wide-angle TE and TM polarization stability

In this research, a new tunable dual-band metamaterial absorber with wide-angle TE and TM polarization stability is proposed. The designed absorber exhibits two high absorption peaks at 5.1 and 8.5 GHz with absorption peaks of 96 and 97%, respectively. The unit cell consists of a metallic background plane and two closed rings including two groups of T-shaped resonators, separated by a low-cost dielectric layer with thickness of 0.9 mm. By tuning the distance between the T-shaped structures and closed ring, the corresponding two resonance frequencies can be effectively separated with high absorption over 95% while keeping the closed ring unchanged. The simulated results demonstrate that the designed absorber has good characteristics of high absorption rates, polarization-insensitiveness and wide angle of incident waves. A waveguide experiment is performed to verify the good agreement between the simulated and measured results.

A Dual Band Polarization-insensitive Tunable Absorber Based on Terahertz MEMS Metamaterial

We present the design, numerical simulations and characterization of a dynamically tunable dual band metamaterial absorber that shows two distinct absorption peaks in terahertz (THz) regime. The designed absorber consists of a metal ground plane fixed on substrate and a movable metamaterial suspended above the ground plane. Through applying a bias voltage to adjust the height between the suspended elements and metal ground plane, we can switch absorber's state between absorption and reflection. Moreover, the designed absorber is polarization-insensitive and can be operated over a wide range of incidence angles owing to the high degree symmetry of designed structure.