Manipulating pattern periods via external bias for graphene‐based <scp>THz Dual‐Band</scp> absorber

Aghaee, Toktam; Orouji, Ali A.

doi:10.1002/mop.32970

Cited by 23 publications

(4 citation statements)

References 19 publications

(27 reference statements)

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“…According to equation (16), the change in gate bias leads to the change in chemical potential, forcing the device to react differently (Aghaee and Orouji, 2021a, 2021b): where V g , ɛ r , ɛ 0 , d and υ f are respectively the gate voltage, the permittivity of the dielectric substrate, the permittivity of free space, the thickness of the dielectric substrate and the Fermi velocity.…”

Section: Simulation Resultsmentioning

confidence: 99%

“…The production of single-layer materials, such as graphene and other 2D materials, predominantly relies on three widely used techniques: cleavage technique, molecular beam epitaxy and chemical vapor deposition (CVD). These methods offer a diverse range of options, encompassing both wet and dry transition structures (Rezaei et al , 2022; Aghaee and Orouji, 2021a, 2021b).…”

Section: Possible Fabrication Methods Of a Graphene/gold/metal-based ...mentioning

confidence: 99%

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An optoelectronic Coupler based on graphene patterns and SU-8 photoresist

Zandi,

Fouladian,

Mazloum

2024

COMPEL

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Purpose The purpose of this research is to efficiently separate incident terahertz (THz) waves into distinct transmission and reflection channels by minimizing the absorption ratio. So, the optical systems operating within the THz frequency range can developed. To achieve a multi-band response, four different periodic arrays of graphene patterns are used. These arrays are strategically stacked on both sides of three SU-8 photoresists, serving as dielectric materials. Consequently, each layer exhibits a unique influence on the device's response, and by applying four external bias voltages, the behavior of the device can be precisely controlled and adjusted. Design/methodology/approach A novel optoelectronic device operating in the THz frequency range is introduced, using periodic arrays of graphene patterns and SU-8 photoresist dielectrics. The design of this device is based on meta-surface principles, using both the equivalent circuit model (ECM) and transmission line concept. The output of the device is a THz coupler implemented by analyzing the reflection and transmission channels. The structure is characterized using the ECM and validated through comprehensive full-wave simulations. By representing the electromagnetic phenomenon with passive circuit elements, enabling the calculation of absorption, reflection and transmission through the application of the theory of maximum power transfer. Findings Based on simulation results and theoretical analysis, the proposed device exhibits sensitivity to gate biasing, enabling efficient reflection and transmission of THz waves. The device achieves reflection and transmission peaks exceeding across the five distinct THz bands 90%, and its behavior can be tuned by external gate biasing. Moreover, the device's sensitivity to variations in geometrical parameters and chemical potentials demonstrates its reliable performance. With its outstanding performance, this high-performance meta-surface emerges as an ideal candidate for fundamental building blocks in larger optical systems, including sensors and detectors, operating within the THz frequency band. Originality/value The proposed device covers a significant portion of the THz gap through the provision of five adjustable peaks for reflection and transmission channels. Additionally, the ECM and impedance matching concept offers a simplified and time-efficient approach to designing the meta-surface. Leveraging this approach, the proposed device is effectively represented using passive circuit elements such as inductors, capacitors and resistors, while its performance is validated through the utilization of the finite element method (FEM) as a full-wave simulation tool. This combination of circuit modeling and FEM simulation contributes to the robustness and accuracy of the device's performance evaluation.

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Section: Simulation Resultsmentioning

confidence: 99%

Section: Possible Fabrication Methods Of a Graphene/gold/metal-based ...mentioning

confidence: 99%

An optoelectronic Coupler based on graphene patterns and SU-8 photoresist

Zandi,

Fouladian,

Mazloum

2024

COMPEL

View full text Add to dashboard Cite

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“…Meanwhile, generally precise conditions are displayed to portray the graphene layer 8 . Additionally, 9,10 displayed proficient circuit models for graphene nano‐strips and graphene nano‐disks, individually, which consider the impacts of physical parameters such as the geometry and electron unwinding time at the side the impacts of predisposition voltage have taken into account. Concurring to numerous past works, the exactness of the circuit demonstrate execution has been compared with numerical strategies, most of which report a really great attention with the slight blunder of the circuit demonstrate strategy versus numerical strategies 11 .…”

Section: Introductionmentioning

confidence: 99%

Two directional THz wave duplexer and filter based on graphene disks and rings

Khani

Fouladian

Mazloum

2023

Int J Numerical Modelling

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Coating both sides of a dielectric spacer with graphene patterns, leads to a tunable meta surface which acts as a THz duplexer. Two separate channels, reflection and transmission are considered as outputs ports while the aim is to minimize absorption ration. The presented structure consists of periodic arrays of graphene patterns on both sides of silicon dioxide as substrate. Moreover, the patterns include disks and rings are biased differently compared to conventional patterns which makes it possible to achieve tunable behaviors versus external bias. utilizing equivalent circuit models (ECM) for graphene patterns and dielectric, the whole structure is modeled by passive RLC branches.According to the simulation outputs, the presented structure can transmit and reflect incident THz waves at desired frequencies in 0.1 THz to 30 THz which makes it an ideal candidate for manipulating THz waves in terms of transmission and reflection. The THz duplexer can transmit and reflect incident waves at 1-3.3 THz as wide-band and 1.05 THz as narrow-band operation. Such a tunable device is in great demand for indoor communications, security, less harmful medical imaging and space related researches.

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“…The conductivity of graphene can be controlled by the bias voltage and chemical doping, in this case, the absorbers based on graphene are much flexible than absorbers based on metal (Biabanifard, 2021). Numerous theoretical designs have introduced with various configurations, such as nanodisk, microribbons, heterostructure and a combination of cross-shaped gold wires and graphene wires (Soltani-Zanjani et al , 2021; Cyrus and Biabanifard, 2021; Aghaee and Orouji, 2020a, 2020b, 2020c; Aghaee and Orouji, 2021a, 2021b).…”

Section: Introductionmentioning

confidence: 99%

A tunable broadband THz absorber using periodic arrays of graphene disks

Khani

Aghaee

Mazloum

et al. 2022

COMPEL

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Purpose A wide band perfect THz absorber is presented in this work. The structure includes two layers of graphene disks on the silicon dioxide dielectric layer while a golden plate is placed at the bottom to act as a fully reflecting mirror against THz waves. According to the simulations, the device is robust enough to show independent operation versus layers thicknesses variations, chemical potentials mismatches and changing of electron relaxation time. The designed THz absorber in this work is an appropriate basic block for several applications in THz optical systems such as sensors, detectors and modulators. Design/methodology/approach The layers in the proposed device are modeled via passive circuit elements and consequently, the equivalent circuit of the device is calculated. Leveraging the developed equivalent circuit model (ECM) and impedance matching concept, the proposed device is designed to perfect absorption with 4.7 THz bandwidth that possesses over 90% absorption. Ample simulations are performed using MATLAB (ECM) and CST (finite element method) to verify the superior performance of the device. According to the simulations, the device is robust enough to show independent operation versus layers thicknesses variations, chemical potentials mismatches and changing of electron relaxation time. Findings This work reports a wideband THz absorber, composed of two graphene layers. This paper considers the circuit model representation for two different layers of the device. For a unique structure, a highly tunable response versus chemical potential is obtained. The circuit model approach and impedance matching theory are exploited to reduce computational time regarding conventional approaches. Originality/value A wide band absorber in THz band is presented. Leveraging circuit model approach and impedance matching theory, the design procedure is simplified regarding CPU time and memory requirements compared to conventional methods. Detailed calculations and ample simulations verify the performance excellency of the device to absorb THz incident waves in 2–6.5 THz frequencies. Also, the robustness of the device is investigated versus parameters mismatches like layers thicknesses and chemical potentials values. According to the simulations and absorption response, the proposed device is an appropriate block to be used in THz optical systems such as detectors, imaging systems and optical modulators.

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Manipulating pattern periods via external bias for graphene‐based THz Dual‐Band absorber

Cited by 23 publications

References 19 publications

An optoelectronic Coupler based on graphene patterns and SU-8 photoresist

An optoelectronic Coupler based on graphene patterns and SU-8 photoresist

Two directional THz wave duplexer and filter based on graphene disks and rings

A tunable broadband THz absorber using periodic arrays of graphene disks

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