Tunable Triple-Band Plasmonically Induced Transparency Effects Based on Double π-Shaped Metamaterial Resonators

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.

     

New Type Design of the Triple-Band and Five-Band Metamaterial Absorbers at Terahertz Frequency

A new scheme to achieve a simple design of triple-band metamaterial absorber at terahertz frequency is presented. In this scheme, we employ a traditional sandwich structure, which is consisted of a metallic resonator and an appropriate thickness of the dielectric layer backed with an opaque metallic board, as the research object. Three strong but discrete resonance peaks with the narrow bandwidths and high absorptivities are realized. The combination of the dipolar resonance, LC (inductor-capacitor circuit) resonance, and the surface resonance of the metallic resonator determines the triple-band absorption. Numerical results also show that the frequencies of the three absorption bands and the number of the resonance peaks can be effectively tuned by adjusting or changing the geometric parameters of the metallic resonator. Moreover, we present a simple design of five-band terahertz absorber by further optimizing the sizes of the metallic elements in the top layer of the metamaterial. The design of the unit structures will assist in designing innovative absorbing devices for spectroscopy imaging, detection, and sensing.     

Single-Patterned Metamaterial Structure Enabling Multi-band Perfect Absorption

Multi-band or broadband perfect metamaterial absorbers, based on coplanar super-unit structure or multiple vertically stacked layers, have received intense attention because of their potential for practical applications. The resonance mechanism of them usually only utilizes the overlapping of the fundamental resonance of the different-sized patterns, and neglects the high-order resonance of the structure, and thus making the proposed structures quite troublesome to be fabricated and the mechanism of the current demonstrated absorbers lack of novelty. In this paper, a simple design of dual-band terahertz absorber consisted of only a traditional square metallic patch and a dielectric layer on top of a continuous ground plane is presented. Simulation results show that the single resonant structure has two resonance absorption peaks, which are both average over 99.5 %. The mechanism of the dual-band absorber is due to the overlapping of the fundamental mode and three-order response of the patterned structure, which is totally different from previous reports that only combining the fundamental resonances of the different-shaped complex structures to obtain the dual-band response. Furthermore, the proposed single-patterned structure can be used to extend the number of the absorption peaks (for example, triple-band absorber) by combining one more resonance (the five-order response). The proposed absorbers with the simple structure design have potential applications in many areas, such as detection, sensing, and selective thermal emitters.     

Design of Dual-Band Plasmon-Induced Transparent Effect Based on Composite Structure of Closed-Ring and Square Patch

Plasmonics - We propose a dual-band transparent window terahertz metamaterial consisting of a closed-ring resonator and a square patch. This structure can achieve two transparent windows with...     

Simplified Design of Quad-Band Terahertz Absorber Based on Periodic Closed-Ring Resonator

Plasmonics - Multiple-band metamaterial absorbers as an important branch of metamaterial-based resonant devices have shown considerable application prospects in real life. However, current designs...     

Resonance Bandwidth Controllable Adjustment of Electromagnetically Induced Transparency-like Using Terahertz Metamaterial

In the fields of communication and sensing, resonance bandwidth is a very critical index. It is very meaningful to implement a broadband resonance device with a simple metamaterial structure in the terahertz band. In this paper, we propose a simple metamaterial structure which consists of one horizontal metal strip and two vertical metal strips. This structure can achieve an electromagnetically induced transparency-like (EIT-like) effect in the frequency range of 0.1~3.0 THz to obtain a transparent window with a resonance bandwidth as high as 1.212 THz. When the relative distance between two vertical metal strips is changed, the bandwidth can be effectively controlled. Furthermore, we found that the EIT-like effect can be actively adjusted by replacing vertical metal strips with photosensitive silicon.

     

Design of a Novel Dual-Band Terahertz Metamaterial Absorber

Plasmonics - We present a novel dual-band terahertz absorber formed by only a patterned U-shaped metallic ring and a metallic ground plane separated by a dielectric layer. Theoretical results show...     

Quad-Band Terahertz Absorber Based on Dipolar Resonances of Metamaterial Resonator

Plasmonics - A novel design of a quad-band metamaterial absorber, which consisted of only a metallic resonator on top of a dielectric spacing layer and a metallic board on the bottom, is presented...