scholarly journals Switchable and Dual-Tunable Multilayered Terahertz Absorber Based on Patterned Graphene and Vanadium Dioxide

Micromachines ◽  
2021 ◽  
Vol 12 (6) ◽  
pp. 619
Author(s):  
Hongyao Liu ◽  
Panpan Wang ◽  
Jiali Wu ◽  
Xin Yan ◽  
Xueguang Yuan ◽  
...  
Keyword(s):  
Fermi Level ◽  
Vanadium Dioxide ◽  
High Performance ◽  
Incidence Angle ◽  
Multilayered Structure ◽  
Dual Band ◽  
Broadband Absorption ◽  
Terahertz Absorber ◽  
Polarization Insensitive ◽  
Absorption Performance

In this paper, a switchable and dual-tunable terahertz absorber based on patterned graphene and vanadium dioxide is proposed and analyzed. By controlling the Fermi level of graphene and the temperature of vanadium dioxide, the device’s function can be switched and its absorbing properties can be tuned. When the vanadium dioxide is in an insulator state, the device can be switched from near-total reflection (>97%) to ultra-broadband absorption (4.5–10.61 THz) as the Fermi level of graphene changes from 0 to 0.8 eV. When the vanadium dioxide is changed to a metal state, the device can act as a single-band absorber (when the Fermi level of graphene is 0 eV) and a dual-band absorber with peaks of 4.16 THz and 7.3 THz (when the Fermi level of graphene is 0.8 eV). Additionally, the absorber is polarization-insensitive and can maintain a stable high-absorption performance within a 55° incidence angle. The multilayered structure shows great potential for switchable and tunable high-performance terahertz devices.

scholarly journals Dual-Band, Polarization-Insensitive, Ultrathin and Flexible Metamaterial Absorber Based on High-Order Magnetic Resonance

Photonics ◽  
2021 ◽  
Vol 8 (12) ◽  
pp. 574
Author(s):  
Duong Thi Ha ◽  
Bui Son Tung ◽  
Bui Xuan Khuyen ◽  
Thanh Son Pham ◽  
Nguyen Thanh Tung ◽  
...  
Keyword(s):  
Magnetic Resonance ◽  
Cylindrical Surface ◽  
Metamaterial Absorber ◽  
High Order ◽  
Dual Band ◽  
Polyimide Substrate ◽  
Planar Model ◽  
Polarization Insensitive ◽  
Absorption Performance ◽  
High Absorption

We demonstrate a dual-band, polarization-insensitive, ultrathin and flexible metamaterial absorber (MA), based on high-order magnetic resonance. By exploiting a flexible polyimide substrate, the thickness of MA came to be 1/148 of the working wavelength. The absorption performance of the proposed structure was investigated for both planar and bending models. In the case of the planar model, a single peak was achieved at a frequency of 4.3 GHz, with an absorption of 98%. Furthermore, additional high-order absorption peaks were obtained by the bending structure on a cylindrical surface, while the fundamental peak with a high absorption was maintained well. Our work might be useful for the realization and the development of future devices, such as emitters, detectors, sensors, and energy converters.

Dual-band and polarization-insensitive terahertz absorber based on fractal Koch curves

2014 ◽  
Vol 23 (5) ◽  
pp. 058102 ◽  
Author(s):  
Yan-Bing Ma ◽  
Huai-Wu Zhang ◽  
Yuan-Xun Li ◽  
Yi-Cheng Wang ◽  
Wei-En Lai ◽  
...  
Keyword(s):  
Dual Band ◽  
Terahertz Absorber ◽  
Polarization Insensitive

scholarly journals Enhanced broadband absorption in nanowire arrays with integrated Bragg reflectors

Nanophotonics ◽  
2018 ◽  
Vol 7 (5) ◽  
pp. 819-825 ◽  
Author(s):  
Mahtab Aghaeipour ◽  
Håkan Pettersson
Keyword(s):  
High Performance ◽  
Incidence Angle ◽  
Solar Spectrum ◽  
Normal Incidence ◽  
Absorption Efficiency ◽  
Nanowire Arrays ◽  
Bragg Reflectors ◽  
Broadband Absorption ◽  
Photovoltaic Applications ◽  
Direct Band

AbstractA near-unity unselective absorption spectrum is desirable for high-performance photovoltaics. Nanowire (NW) arrays are promising candidates for efficient solar cells due to nanophotonic absorption resonances in the solar spectrum. The absorption spectra, however, display undesired dips between the resonance peaks. To achieve improved unselective broadband absorption, we propose to enclose distributed Bragg reflectors (DBRs) in the bottom and top parts of indium phosphide (InP) NWs, respectively. We theoretically show that by enclosing only two periods of In0.56Ga0.44As/InP DBRs, an unselective 78% absorption efficiency (72% for NWs without DBRs) is obtained at normal incidence in the spectral range from 300 nm to 920 nm. Under oblique light incidence, the absorption efficiency is enhanced up to about 85% at an incidence angle of 50°. By increasing the number of DBR periods from two to five, the absorption efficiency is further enhanced up to 95% at normal incidence. In this work, we calculated optical spectra for InP NWs, but the results are expected to be valid for other direct band gap III–V semiconductor materials. We believe that our proposed idea of integrating DBRs in NWs offers great potential for high-performance photovoltaic applications.

Narrowband-to-broadband switchable and polarization-insensitive terahertz metasurface absorber enabled by phase-change material

2021 ◽  
Author(s):  
Seyed Hadi Badri ◽  
M. M. Gilarlue ◽  
Sanam SaeidNahaei ◽  
Jong Su KIM
Keyword(s):  
Phase Change ◽  
Phase Change Material ◽  
Ground Plane ◽  
Metallic State ◽  
Broadband Absorber ◽  
Broadband Absorption ◽  
Terahertz Absorber ◽  
Wide Range ◽  
Polarization Insensitive ◽  
Change Material

Abstract A terahertz absorber with controllable and switchable bandwidth and insensitive to polarization is of great interest. Here, we propose and demonstrate a metasurface absorber with switchable bandwidth based on a phase-change material of vanadium dioxide (VO2) and verify its performance by the finite element method simulations. The metasurface absorber is composed of a hybrid cross fractal as a resonator separated from a gold ground-plane by a polyimide spacer. Switching from narrowband to broadband absorber is achieved via connecting VO2 patches to the gold first-order cross fractal converting the resonator to a third-order cross fractal. In the insulator phase of VO2, the main narrowband absorption occurs at the frequency of 6.05 THz with a 0.99 absorption and a full-width half-maximum (FWHM) of 0.35 THz. Upon insulator-to-metal transition of VO2, the metasurface achieves a broadband absorption with the FWHM of 6.17 THz. The simulations indicate that by controlling the partial phase-transition of VO2, we can tune the bandwidth and absorption level of the absorber. Moreover, the designed absorber is insensitive to polarization due to symmetry and works well for a very wide range of incident angles. In the metallic state of VO2, the absorber has an absorption exceeding 0.5 in the 3.57-8.45 THz frequency range with incident angles up to 65°.

scholarly journals Numerical Investigation of Graphene and STO Based Tunable Terahertz Absorber with Switchable Bifunctionality of Broadband and Narrowband Absorption

Nanomaterials ◽  
2021 ◽  
Vol 11 (8) ◽  
pp. 2044
Author(s):  
Yan Liu ◽  
Rui Huang ◽  
Zhengbiao Ouyang
Keyword(s):  
Energy Level ◽  
Fermi Energy ◽  
High Performance ◽  
Thermal Control ◽  
Rate Of Change ◽  
Center Frequency ◽  
Fermi Energy Level ◽  
Broadband Absorption ◽  
Terahertz Absorber ◽  
The Cross

A graphene metamaterial and strontium titanate (STO)-based terahertz absorber with tunable and switchable bifunctionality has been numerically investigated in this work. Through electrically tuning the Fermi energy level of the cross-shaped graphene, the bandwidth of the proposed absorber varies continuously from 0.12 THz to 0.38 THz with the absorptance exceeding 90%, which indicates the functionality of broadband absorption. When the Fermi energy level of the cross-shaped graphene is 0 eV, the proposed absorber exhibits the other functionality of narrowband absorption owing to the thermal control of the relative permittivity of STO, and the rate of change of the center frequency is 50% ranging from 0.56 THz to 0.84 THz. The peak intensity of the narrowband absorption approximates to nearly 100% through adjusting the Fermi energy level of the graphene strips. The calculated results indicate that it is not sensitive to the polarization for wide incidence angles. The proposed absorber can realize tunable bifunctionality of broadband absorption with a tunable bandwidth and narrowband absorption with a tunable center frequency, which provides an alternative design opinion of the tunable terahertz devices with high performance for high-density integrated systems.

scholarly journals Highly Transparent Broadband and Polarization-Insensitive Absorber Based on Metasurface

2020 ◽  
Vol 10 (24) ◽  
pp. 9125
Author(s):  
Houdi Xiao ◽  
Ruiru Qin ◽  
Mingyun Lv ◽  
Chuanzhi Wang
Keyword(s):  
Incidence Angle ◽  
Wide Band ◽  
Metamaterial Absorber ◽  
Light Transmittance ◽  
Cutoff Wavelength ◽  
Broadband Absorption ◽  
Low Profile ◽  
Wide Range ◽  
Potential Applications ◽  
Polarization Insensitive

A highly transparent polarization-insensitive metamaterial absorber with wideband microwave absorption is presented. The broadband absorption (6.0~16.7 GHz, absorptance > 85%) is achieved using three patterned resistive metasurfaces. The visible light transmittance of the absorber is as high as 85.7%. The thickness of the absorber is 4.42 mm, which is only 0.088 times of the upper-cutoff wavelength. A prototype sample is fabricated and measured to demonstrate its excellent performance. The experimental results agree well with the simulation results. In view of its wide band absorption, high transmittance, low profile, polarization insensitivity and wide incidence angle stability, the presented absorber has a wide range of potential applications.

scholarly journals A thermally stable and polarization insensitive square-shaped water metamaterial with ultra-broadband absorption

2021 ◽  
Author(s):  
Yadgar I. Abdulkarim ◽  
Halgurd N. Awl ◽  
Fatih Ozkan Alkurt ◽  
Fahmi F. Muhammadsharif ◽  
Salah Raza Saeed ◽  
...  
Keyword(s):  
Thermally Stable ◽  
Broadband Absorption ◽  
Polarization Insensitive

Fermi‐Level Pinning Free High‐Performance 2D CMOS Inverter Fabricated with Van Der Waals Bottom Contacts

2021 ◽  
pp. 2001212
Author(s):  
Tien Dat Ngo ◽  
Zheng Yang ◽  
Myeongjin Lee ◽  
Fida Ali ◽  
Inyong Moon ◽  
...  
Keyword(s):  
Fermi Level ◽  
High Performance ◽  
Van Der Waals ◽  
Cmos Inverter ◽  
Fermi Level Pinning
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