Ultra-broadband Tunable Terahertz Absorber Based on Hollow Fan Patterned VO<sub>2</sub> Metamaterials

In-Ho Pak; Hyok-Ju Kim; Kwang-Jin Ri; Song-Il Ri

doi:doi:10.11648/j.sjac.20250902.12

Research Article |

| Peer-Reviewed

Ultra-broadband Tunable Terahertz Absorber Based on Hollow Fan Patterned VO₂ Metamaterials

In-Ho Pak

, Hyok-Ju Kim

, Kwang-Jin Ri^*

, Song-Il Ri

Published in Science Journal of Analytical Chemistry (Volume 13, Issue 3)

Received: 25 August 2025 Accepted: 12 September 2025 Published: 14 November 2025

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Abstract

A novel design of ultra-broadband tunable terahertz (THz) absorber based on hollow fan patterned VO₂ metamaterials is proposed and investigated. Our designed metamaterial absorber (MA) is aimed at expanding the absorption bandwidth, simplifying the structure and reducing the volume as much as possible. It is really proved from simulation results that the proposed MA has not only simple structure and small volume but also ultra-broadband absorption above 90% ranging from 2.92 THz to 10.05 THz. Comparing with previous studies, the proposed MA greatly improved its performances in several aspects of absorption bandwidth, tunable range, simple structure and small volume. Increasing the VO₂ conductivity from 200 S/m to 2×10⁵ S/m, the absorption rate of proposed MA rapidly increases from 1.2% to 99.2%, thus the proposed MA has the high tuning performance with maximum modulation depth of 98.8%. We also investigate the absorption origin of proposed MA by using the electric field distributions. The proposed MA achieves the ultra-broadband absorption by the fundamental resonance and high-order resonances of hollow fan VO₂ pattern. In addition, all the influences of polarization angle, incidence angle and geometrical parameters on the ultra-broadband absorption are analyzed in detail. Our designed MA may be widely utilized for practical applications of THz technology.

Published in	Science Journal of Analytical Chemistry (Volume 13, Issue 3)
DOI	10.11648/j.sjac.20250902.12
Page(s)	22-30
Creative Commons	This is an Open Access article, distributed under the terms of the Creative Commons Attribution 4.0 International License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution and reproduction in any medium or format, provided the original work is properly cited.
Copyright	Copyright © The Author(s), 2025. Published by Science Publishing Group

Keywords

Metamaterial Absorber, Ultra-broadband, Tunable, Vanadium Dioxide, Hollow, Fan

1. Introduction

Metamaterials, a kind of artificially structured materials characterized by meta-atoms customized for user purposes exhibit exotic electromagnetic properties such as negative refractive index

[1]

, invisible cloaking

[2]

, perfect absorption

[3]

that are not capable of existing in ordinary materials. The interesting features of metamaterials have been effectively utilized for many functional devices such as absorbers

[4]

, filters

[5]

, polarization converters

[6]

, and hyperlens

[7]

. In particular, metamaterial absorbers (MAs) have many meaningful applications such as stealth camouflage

[8]

, sensing

[9]

, energy harvesting

[10]

, and wireless communications

[11]

. After the first microwave MA with perfect absorption was demonstrated by Landy et al

[3]

, numerous MAs have been proposed and demonstrated in various frequency bands ranging from microwave, terahertz (THz), infrared to optical domains

[12-16]

, involving multi-band and broadband absorption

[17-21]

. As well known, the broadband MAs are greatly valuable because of their extensive applications including thermal emitting, energy harvesting, security imaging and shielding

[22]

. Simultaneously, their absorption tunability is eminently desirable for optoelectronic devices such as modulators and switches

[23]

. Therefore, the development of tunable broadband MAs has been the attractive topic.

Recently, many studies on the MAs have been considerably focused on the THz MAs working in the frequency band ranging from 0.1 THz to 10THz. The great improvement of THz technology has accelerated the practical applications of THz MAs in many functional devices. For example, multi-band THz MAs with high performance are very useful for THz sensors

[24]

, while tunable broadband MAs are very useful for THz communications

[25]

Active materials including vanadium dioxide (VO₂) and graphene are necessarily required for tunable THz MAs. Here, we think that VO₂ is preferable rather than graphene. In the case of utilization of graphene for tunable MAs, the Fermi energy of graphene can adjusted by the bias voltage, which accompanies external electrodes, thus resulting in the complexity of the total structure

[26, 27]

. In addition, the fabrication of ultra-thin graphene layer still faces challenges. On the contrary, VO₂ has acquired great popularity because of the reversible phase transition property and the easy tunability of conductivity. Indeed, VO₂ can be considered as a good candidate for tunable MAs, because it leads to the dramatic increase of conductivity to several orders of magnitude throughout the phase transition process and ensures the high modulation performance in THz functional devices

[28]

Until now, many significant researches on tunable THz MAs based on VO₂ have been reported. For instance, Yang et al demonstrated a tunable broadband THz absorber based on VO₂ metamaterials, whose working bandwidth was 3.78 THz with absorptivity above 90% ranging from 3.01 THz to 6.79 THz

[29]

. Ahmed et al investigated an ultra-broadband THz MA with two M-shaped VO₂ rings, whose absorption rate can reach above 90% between 4.15 THz to 8.43 THz

[30]

. Pan et al proposed a tunable ultra-broadband THz MA excited by the toroidal dipole moments, which achieved the absorption over 90% in the range of 2.38-21.13 THz, with relative absorption bandwidth of 159.5%

[31]

. Additionally, Feng et al investigated a tunable dual-broadband THz absorber with hybrid VO₂ metamaterial, whose working bandwidths with absorption above 90% were extended to 3.4 THz and 3.06 THz. However, this MA is not appropriate for practical applications because of the complicated structure

[32]

. Zhang et al designed an ultra-broadband tunable THz MA using bilayer VO₂ square ring arrays. The proposed absorber achieved high absorptivity more than 90% ranging from 1.63 THz to 12.39 THz, with relative bandwidth of 153.5%

[33]

Although these recent tunable MAs have greatly improved their performances compared to previous MAs, they still face some challenges including further expansion of absorption bandwidth

[29, 30]

, simplification of complex structures

[31, 32]

and reduction of large volumes

[33]

. Therefore, the continuous development of broadband tunable THz MAs with simple structure and small volume is absolutely necessary

[34-37]

In this paper, we theoretically investigate a novel design of ultra-broadband tunable THz absorber based on hollow fan patterned VO₂ metamaterials. As expected, the proposed MA has not only simple structure and small volume but also ultra-broadband absorption above 90% ranging from 2.92 THz to 10.05 THz. Moreover, the proposed MA achieves the high tuning performance with maximum modulation depth of 98.8%. Comparing with previous studies

[28]	Y. C. Liu, Y. X. Qian, F. R. Hu, et al., A dynamically adjustable broadband terahertz absorber based on a vanadium dioxide hybrid metamaterial, Results in Physics 19(2020): 103384. https://doi.org/10.1016/j.rinp.2020.103384 View Article
[29]	G. S. Yang, F. P. Yan, X. M. Du, et al., Tunable broadband terahertz metamaterial absorber based on vanadium dioxide, AIP Advances 12(2022): 045219. https://doi.org/10.1063/5.0082295 View Article
[30]	M. R. Ahmed, O. Jyoti, F. Farjana, P. P. Sarkar, A. K. Paul, and M. S. Habib, Theoretical and numerical investigation of an ultra-broadband near-perfect absorption in auxetic metamaterials, Optics Continuum 3(2024): 2139-2149. https://doi.org/10.1364/OPTCON.539561 View Article
[31]	H. Pan, H. F. Zhang, Thermally tunable polarization-insensitive ultra-broadband terahertz metamaterial absorber based on the coupled toroidal dipole modes, Optics Express 29(2021): 18081-18094. https://doi.org/10.1364/OE.427554 View Article
[32]	H. L. Feng, Z. X. Zhang, J. Y. Zhang, D. C. Fang, et al., Tunable Dual-Broadband Terahertz Absorber with Vanadium Dioxide Metamaterial, Nanomaterials 12(2022): 1731. https://doi.org/10.3390/nano12101731 View Article
[33]	P. Y. Zhang, G. Q. Chen, Z. Y. Hou, Y. Z. Zhang, et al., Ultra-broadband tunable terahertz metamaterial absorber based on double-layer vanadium dioxide square ring arrays, Micromachines 13(2022): 669. https://doi.org/10.3390/mi13050669 View Article
[34]	Y. J. Wang, Y. Y. Chen, F. Liu, L. Chen, et al., Vanadium dioxide enabled polarization insensitive tunable broadband terahertz metamaterial absorber, Scientific Reports 15(2025): 10140. https://doi.org/10.1038/s41598-025-94645-3 View Article
[35]	Y. Q. Zhu, Vanadium dioxide-based tunable broadband metamaterial absorber in the terahertz, Materials Research Express 12(2025): 015801. https://doi.org/10.1088/2053-1591/ada41b View Article
[36]	M. A. Islam, M. R. Ahmed, O. Jyoti, et al., Analysis of an ultra-broadband terahertz metamaterial absorber, Optics Continuum 4(2025): 756-769. https://doi.org/10.1364/OPTCON.557405 View Article
[37]	L. Gevorgyan, H. Haroyan, H. Parsamyan, K Nerkararyan, Tunable ultra-broadband terahertz metamaterial absorber based on vanadium dioxide strips, RSC Advances 13(2023): 11948. https://doi.org/10.1039/d3ra01194a View Article

[28-37]

, the proposed MA greatly improved its performances in several aspects of absorption bandwidth, tunable range, simple structure and small volume. We also investigate the absorption origin of proposed MA. In addition, all the influences of polarization angle, incidence angle and geometrical parameters on the ultra-broadband absorption are analyzed in detail.

2. Design and Simulation

The schematic of our designed MA unit cell is illustrated in Figure 1. The proposed structure is constructed of three layers: the gold layer with conductivity of σ = 4.561×10⁷ S/m is placed on the bottom, the lossless dielectric layer with relative permittivity of 1.96

[38]

is placed on the gold layer, and the hollow fan patterned VO₂ layer is placed on the middle dielectric layer. At the THz band, the relative permittivity of VO₂ described by Drude model is given as

[39]

(1)

Herein,

ε_{\infty} = 12

is the infinite-frequency dielectric constant,

=5.75×10¹³ rad/s indicates the collision frequency. The plasma frequency

ω_{p} (σ)

is related to conductivity of VO₂(

σ_{V O_{2}}

) as follows:

(2)

Here,

σ_{0}

=3×10⁵ S/m and

ω_{p} (σ_{0})

=1.4×10¹⁵ rad/s. VO₂ has the conductivity of 2×10⁵ S/m when it works as a metal at T = 350 K and has the conductivity of 200 S/m when it works as an insulator at T = 300 K

[40]

. The geometrical parameters extracted from the optimal design of MA unit cell are given in Table 1.

Table 1. Geometrical parameters of the designed MA.

P	R₁	R₂	g	w	h₁	h₂	h₃
22 μm	9 μm	9.5 μm	2.5 μm	2.25 μm	0.2 μm	8 μm	0.2 μm

Download: Download full-size image

Figure 1. Schematic of the designed MA unit cell: (a) front view, (b) side view.

All the numerical simulations of the proposed MA are carried out by the well-known software CST STUDIO SUITE 2018. Here, we allocate the boundary condition of unit cell to the x- and y- axes, while the boundary condition for the z-axis is set to open (add space). The proposed MA is exposed to the plane electromagnetic wave directed to the negative z-direction. We generally simulate the absorption rate of proposed MA at TE and TM modes. For TE (TM) mode, the electric field vector of incident THz wave is directed to the y-axis (x-axis)

[41]

. The frequency-dependent absorption rate of MA is expressed as

A (ω) = 1 - R (ω) - T (ω)

, where

R (ω) = {|S_{11} (ω)|}^{2}

is the reflection and

{T (ω) = |S_{21} (ω)|}^{2}

is the transmission. In our MA design, the continuous gold layer is located at the bottom, which completely prevents the transmission of electromagnetic waves, that is:

{T (ω) = |S_{21} (ω)|}^{2} = 0

. Therefore, the absorption rate is expressed as simpler Eq.

A (ω) = 1 - R (ω)

3. Results and Discussion

Download: Download full-size image

Figure 2. (a) Absorption and reflection spectra of proposed MA, (b) Color map of absorption spectra with the variation of polarization angles, (c) Absorption behaviors of the MAs with different VO₂ patterns.

The absorption (A) and reflection (R) spectra of proposed MA for TE mode are plotted in Figure 2(a). When VO₂ acts as a metal, with conductivity of 2×10⁵ S/m, the absorption rate of proposed MA exceeds 90% in the frequency band ranging from 2.92 THz to 10.05 THz. Within the absorption band, the proposed MA has three resonant peaks with absorption rates of 99.25%, 95.83%, 97.20% at 3.36 THz, 6.44 THz, 9.38 THz, respectively. The influence of polarization angle on the absorption rate of proposed MA is investigated. As shown in Figure 2(b), the absorption rate of proposed MA is hardly affected by the polarization angle. That is, the proposed MA is polarization-independent. To intuitively show the seeking process of the proposed MA design, the absorption spectra of MAs using three VO₂ patterns are plotted in Figure 2(c). Starting from the first dual-band MA with circular VO₂ patch, we achieved the final ultra-broadband MA with hollow fan VO₂ pattern via the second broadband MA with fan VO₂ pattern.

The conductivity of VO₂ depends on the ambient temperature. Thus, we can change the conductivity of VO₂ by altering the temperature. In some applications including THz communications, the phase transition time of VO₂ decides the modulation speed of THz device. For this reason, we may elect the photo-excited phase transition method as the available technique, where the employed strong laser pulses have timescale less than several picoseconds

[42-44]

. Figure 3 shows the absorption tunability of designed MA corresponding to the variation of VO₂ conductivity. Increasing the VO₂ conductivity from 200 S/m to 2×10⁵ S/m, the absorption rate of proposed MA rapidly increases from 1.2% to 99.2%. From these simulation results, we can estimate the modulation depth (MD) of our tunable MA via MD = (A_m-A_i)/A_m×100. Here, A_m and A_i indicate the absorption rates corresponding to metal and insulator states of VO₂, respectively

[45]

. The proposed MA achieves high MD of 98.8% at 3.36 THz.

Download: Download full-size image

Figure 3. Absorption tunability of designed MA with change of VO₂ conductivity.

In addition, one of the important factors characterized the MAs is a relative absorption bandwidth (RAB), which is the proportion of absorption bandwidth to the central frequency. As shown in Table 2, the RAB of proposed MA reaches to 109.94%, higher than those of other MAs reported in Refs.

[28]	Y. C. Liu, Y. X. Qian, F. R. Hu, et al., A dynamically adjustable broadband terahertz absorber based on a vanadium dioxide hybrid metamaterial, Results in Physics 19(2020): 103384. https://doi.org/10.1016/j.rinp.2020.103384 View Article
[29]	G. S. Yang, F. P. Yan, X. M. Du, et al., Tunable broadband terahertz metamaterial absorber based on vanadium dioxide, AIP Advances 12(2022): 045219. https://doi.org/10.1063/5.0082295 View Article
[30]	M. R. Ahmed, O. Jyoti, F. Farjana, P. P. Sarkar, A. K. Paul, and M. S. Habib, Theoretical and numerical investigation of an ultra-broadband near-perfect absorption in auxetic metamaterials, Optics Continuum 3(2024): 2139-2149. https://doi.org/10.1364/OPTCON.539561 View Article
[31]	H. Pan, H. F. Zhang, Thermally tunable polarization-insensitive ultra-broadband terahertz metamaterial absorber based on the coupled toroidal dipole modes, Optics Express 29(2021): 18081-18094. https://doi.org/10.1364/OE.427554 View Article
[32]	H. L. Feng, Z. X. Zhang, J. Y. Zhang, D. C. Fang, et al., Tunable Dual-Broadband Terahertz Absorber with Vanadium Dioxide Metamaterial, Nanomaterials 12(2022): 1731. https://doi.org/10.3390/nano12101731 View Article
[33]	P. Y. Zhang, G. Q. Chen, Z. Y. Hou, Y. Z. Zhang, et al., Ultra-broadband tunable terahertz metamaterial absorber based on double-layer vanadium dioxide square ring arrays, Micromachines 13(2022): 669. https://doi.org/10.3390/mi13050669 View Article
[34]	Y. J. Wang, Y. Y. Chen, F. Liu, L. Chen, et al., Vanadium dioxide enabled polarization insensitive tunable broadband terahertz metamaterial absorber, Scientific Reports 15(2025): 10140. https://doi.org/10.1038/s41598-025-94645-3 View Article
[35]	Y. Q. Zhu, Vanadium dioxide-based tunable broadband metamaterial absorber in the terahertz, Materials Research Express 12(2025): 015801. https://doi.org/10.1088/2053-1591/ada41b View Article
[36]	M. A. Islam, M. R. Ahmed, O. Jyoti, et al., Analysis of an ultra-broadband terahertz metamaterial absorber, Optics Continuum 4(2025): 756-769. https://doi.org/10.1364/OPTCON.557405 View Article
[37]	L. Gevorgyan, H. Haroyan, H. Parsamyan, K Nerkararyan, Tunable ultra-broadband terahertz metamaterial absorber based on vanadium dioxide strips, RSC Advances 13(2023): 11948. https://doi.org/10.1039/d3ra01194a View Article

[28-37]

except

[31]

. Although the MA reported in Ref.

[31]

has the RAB of 159.5%, it employs the more complicated structure. Moreover, it has the larger thickness and narrow tunable range. On the contrary, our designed structure is simple and has the thin thickness and wide tunable range.

Table 2. Comparison of the designed MA with previous tunable MAs.

Ref.

Absorption bandwidth (THz)

RAB (%)

Tunable range (%)

Thickness (μm)

[28]

1 (0.7-1.7)

83.33

3-90

31.4

[29]

3.78 (3.01-6.79)

77.14

2.7-98.9

8.2

[30]

4.28 (4.15-8.43)

68.04

2-100

8.9

[31]

18.75 (2.38-21.13)

159.5

39-96

20.5

[34]

6.35 (2.82-9.17)

105.92

2-100

8.38

[35]

5.19 (2.32-7.51)

106.12

2-100

11.2

[36]

7.40 (4.51-11.90)

90.18

2-98

6.25

[37]

1.18 (0.66-1.84)

94.4

3-95

39.2

This paper

7.13 (2.92-10.05)

109.94

1.2-99.2

8.4

Download: Download full-size image

Figure 4. Relative impedance and absorption spectra of designed MA.

The impedance matching theory is commonly employed for explaining the absorption principle of MAs

[45]

. In this theory, the frequency-dependent relative impedance of MA is given as:

(3)

Using the Eq. (3), we calculated the frequency-dependent relative impedance of proposed MA. As shown in Figure 4, within the frequency band with absorption rate above 90%, the real part of Z(ω) is close to 1, while the imaginary part of Z(ω) is close to 0. That is, the impedance of proposed MA is well matched with free space, ensuring the ultra-broadband absorption capability.

Download: Download full-size image

Figure 5. Electric field (E_z) distributions simulated at (a) f₁=3.36 THz, (b) f₂=6.44 THz, (c) f₃=9.38 THz.

To better reveal the physical origin of proposed MA, electric field distributions are simulated and investigated at three resonant peaks (f₁, f₂, f₃). As shown in Figure 5(a), at f₁=3.36 THz, the intense electric field concentrates on the upper half and lower half of hollow fan VO₂ pattern, exciting the electric dipolar resonance. Then, another electric dipolar resonance with opposite direction is induced at bottom gold layer. The coupling of these two electric dipolar resonances produces the magnetic resonance. So, the first absorption peak results from the electric dipolar resonance and magnetic resonance. At f₂=6.44 THz, the electric field strongly concentrates on the edges around the gaps as shown in Figure 5(b), resulting in the three electric dipoles. As a result, the electric hexapolar resonances are formed at the top VO₂ pattern and the bottom metal layer, respectively. Then, the couple of these two electric hexapoles excites the three-harmonic magnetic resonance. So, the second absorption peak is generated by the electric hexapolar resonance and the three-harmonic magnetic resonance. At f₃=9.38 THz, the electric field distribution looks very similar to that of f₂=6.44 THz as shown in Figure 5(c). That is, the third absorption peak is also supported by the electric hexapolar resonance and the three-harmonic magnetic resonance

[45]

. To sum up, the proposed MA achieves the ultra-broadband absorption by the fundamental resonance and high-order resonances of hollow fan VO₂ pattern.

The effects of geometrical parameters on the absorption rate of proposed MA are shown in Figure 6. As shown in Figure 6(a), increasing the unit cell periodicity P, the absorption rate of proposed MA increases, but its absorption bandwidth decreases. This absorption behavior is attributed to the coupling resonance effect between the adjacent unit cells. As plotted in Figure 6(b), the increase of inner radius R₁ mainly influences the absorption at high simulation frequency interval. When the outer radius R₂ increases, the working bandwidth of proposed MA increases, but its absorption rate decreases as shown in Figure 6(c). When the geometrical parameter g increases, the absorption rate of proposed MA significantly increases in the middle frequency band as shown in Figure 6(d). Meanwhile, we can see from Figure 6(e) that the absorption rate of proposed MA is very sensitive to the variation of geometrical parameter w. As shown in Figure 6(f), increasing the thickness h₂, the central frequency of working band of proposed MA is red-shifted. This red-shift behavior is attributed to the Fabry-Perot resonance of the middle dielectric layer. The rise of thickness h₂ causes the increase in the length of resonant cavity, thus generating the red-shift of ultra-broadband absorption

[45]

Download: Download full-size image

Figure 6. Effects of geometrical parameters on the absorption rate of proposed MA: (a) P, (b) R₁, (c) R₂, (d) g, (e) w and (f) h_2.

Download: Download full-size image

Figure 7. Influence of incident angle on the absorption rate of proposed MA for (a) TE and (b) TM waves.

Finally, we investigated the influence of incident angle on the absorption rate of proposed MA. As shown in Figure 7(a), the rise of incident angle causes the decrease of absorption rate of proposed MA within the frequency band ranging from 2.92 THz to 10.05 THz. However, the proposed MA still has absorption rate over 72% at incident angle below 50° for TE mode. This absorption behavior is attributed to the attenuation of effective magnetic resonance with rise of incident angle. For TM mode, the rise of incident angle causes a bit of decrease in the absorption rate of proposed MA as shown in Figure 7(b). The proposed MA still has absorption rate above 86% for incident angle below 60°. So, we believe that the proposed MA has stable absorption performance with wide incident angle.

4. Conclusion

We have proposed and investigated a novel design of ultra-broadband tunable THz absorber based on hollow fan patterned VO₂ metamaterials, which can easily achieve the expansion of absorption bandwidth, simplification of the structure and reduction of the volume. The proposed MA has the ultra-broadband absorption above 90% ranging from 2.92 THz to 10.05 THz. Moreover, the proposed MA can achieve high tuning performance with maximum modulation depth of 98.8%. The ultra-broadband absorption capability of proposed MA results from the fundamental resonance and high-order resonances of hollow fan VO₂ pattern. Comparing with previous studies

[28]	Y. C. Liu, Y. X. Qian, F. R. Hu, et al., A dynamically adjustable broadband terahertz absorber based on a vanadium dioxide hybrid metamaterial, Results in Physics 19(2020): 103384. https://doi.org/10.1016/j.rinp.2020.103384 View Article
[29]	G. S. Yang, F. P. Yan, X. M. Du, et al., Tunable broadband terahertz metamaterial absorber based on vanadium dioxide, AIP Advances 12(2022): 045219. https://doi.org/10.1063/5.0082295 View Article
[30]	M. R. Ahmed, O. Jyoti, F. Farjana, P. P. Sarkar, A. K. Paul, and M. S. Habib, Theoretical and numerical investigation of an ultra-broadband near-perfect absorption in auxetic metamaterials, Optics Continuum 3(2024): 2139-2149. https://doi.org/10.1364/OPTCON.539561 View Article
[31]	H. Pan, H. F. Zhang, Thermally tunable polarization-insensitive ultra-broadband terahertz metamaterial absorber based on the coupled toroidal dipole modes, Optics Express 29(2021): 18081-18094. https://doi.org/10.1364/OE.427554 View Article
[32]	H. L. Feng, Z. X. Zhang, J. Y. Zhang, D. C. Fang, et al., Tunable Dual-Broadband Terahertz Absorber with Vanadium Dioxide Metamaterial, Nanomaterials 12(2022): 1731. https://doi.org/10.3390/nano12101731 View Article
[33]	P. Y. Zhang, G. Q. Chen, Z. Y. Hou, Y. Z. Zhang, et al., Ultra-broadband tunable terahertz metamaterial absorber based on double-layer vanadium dioxide square ring arrays, Micromachines 13(2022): 669. https://doi.org/10.3390/mi13050669 View Article
[34]	Y. J. Wang, Y. Y. Chen, F. Liu, L. Chen, et al., Vanadium dioxide enabled polarization insensitive tunable broadband terahertz metamaterial absorber, Scientific Reports 15(2025): 10140. https://doi.org/10.1038/s41598-025-94645-3 View Article
[35]	Y. Q. Zhu, Vanadium dioxide-based tunable broadband metamaterial absorber in the terahertz, Materials Research Express 12(2025): 015801. https://doi.org/10.1088/2053-1591/ada41b View Article
[36]	M. A. Islam, M. R. Ahmed, O. Jyoti, et al., Analysis of an ultra-broadband terahertz metamaterial absorber, Optics Continuum 4(2025): 756-769. https://doi.org/10.1364/OPTCON.557405 View Article
[37]	L. Gevorgyan, H. Haroyan, H. Parsamyan, K Nerkararyan, Tunable ultra-broadband terahertz metamaterial absorber based on vanadium dioxide strips, RSC Advances 13(2023): 11948. https://doi.org/10.1039/d3ra01194a View Article

[28-37]

, the proposed MA greatly improved its performances in several aspects of absorption bandwidth, tunable range, simple structure and small volume. So, our designed MA may be widely utilized for practical applications of THz technology.

Abbreviations

MA	Metamaterial Absorber
THz	Terahertz
RAB	Relative Absorption Bandwidth
MD	Modulation Depth
TE	Transverse Electric
TM	Transverse Magnetic

Conflicts of Interest

The authors declare no conflicts of interest.

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Pak, I., Kim, H., Ri, K., Ri, S. (2025). Ultra-broadband Tunable Terahertz Absorber Based on Hollow Fan Patterned VO2 Metamaterials. Science Journal of Analytical Chemistry, 13(3), 22-30. https://doi.org/10.11648/j.sjac.20250902.12

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Pak, I.; Kim, H.; Ri, K.; Ri, S. Ultra-broadband Tunable Terahertz Absorber Based on Hollow Fan Patterned VO2 Metamaterials. Sci. J. Anal. Chem. 2025, 13(3), 22-30. doi: 10.11648/j.sjac.20250902.12

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Pak I, Kim H, Ri K, Ri S. Ultra-broadband Tunable Terahertz Absorber Based on Hollow Fan Patterned VO2 Metamaterials. Sci J Anal Chem. 2025;13(3):22-30. doi: 10.11648/j.sjac.20250902.12

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@article{10.11648/j.sjac.20250902.12,
  author = {In-Ho Pak and Hyok-Ju Kim and Kwang-Jin Ri and Song-Il Ri},
  title = {Ultra-broadband Tunable Terahertz Absorber Based on Hollow Fan Patterned VO2 Metamaterials
},
  journal = {Science Journal of Analytical Chemistry},
  volume = {13},
  number = {3},
  pages = {22-30},
  doi = {10.11648/j.sjac.20250902.12},
  url = {https://doi.org/10.11648/j.sjac.20250902.12},
  eprint = {https://article.sciencepublishinggroup.com/pdf/10.11648.j.sjac.20250902.12},
  abstract = {A novel design of ultra-broadband tunable terahertz (THz) absorber based on hollow fan patterned VO2 metamaterials is proposed and investigated. Our designed metamaterial absorber (MA) is aimed at expanding the absorption bandwidth, simplifying the structure and reducing the volume as much as possible. It is really proved from simulation results that the proposed MA has not only simple structure and small volume but also ultra-broadband absorption above 90% ranging from 2.92 THz to 10.05 THz. Comparing with previous studies, the proposed MA greatly improved its performances in several aspects of absorption bandwidth, tunable range, simple structure and small volume. Increasing the VO2 conductivity from 200 S/m to 2×105 S/m, the absorption rate of proposed MA rapidly increases from 1.2% to 99.2%, thus the proposed MA has the high tuning performance with maximum modulation depth of 98.8%. We also investigate the absorption origin of proposed MA by using the electric field distributions. The proposed MA achieves the ultra-broadband absorption by the fundamental resonance and high-order resonances of hollow fan VO2 pattern. In addition, all the influences of polarization angle, incidence angle and geometrical parameters on the ultra-broadband absorption are analyzed in detail. Our designed MA may be widely utilized for practical applications of THz technology.
},
 year = {2025}
}

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TY  - JOUR
T1  - Ultra-broadband Tunable Terahertz Absorber Based on Hollow Fan Patterned VO2 Metamaterials

AU  - In-Ho Pak
AU  - Hyok-Ju Kim
AU  - Kwang-Jin Ri
AU  - Song-Il Ri
Y1  - 2025/11/14
PY  - 2025
N1  - https://doi.org/10.11648/j.sjac.20250902.12
DO  - 10.11648/j.sjac.20250902.12
T2  - Science Journal of Analytical Chemistry
JF  - Science Journal of Analytical Chemistry
JO  - Science Journal of Analytical Chemistry
SP  - 22
EP  - 30
PB  - Science Publishing Group
SN  - 2376-8053
UR  - https://doi.org/10.11648/j.sjac.20250902.12
AB  - A novel design of ultra-broadband tunable terahertz (THz) absorber based on hollow fan patterned VO2 metamaterials is proposed and investigated. Our designed metamaterial absorber (MA) is aimed at expanding the absorption bandwidth, simplifying the structure and reducing the volume as much as possible. It is really proved from simulation results that the proposed MA has not only simple structure and small volume but also ultra-broadband absorption above 90% ranging from 2.92 THz to 10.05 THz. Comparing with previous studies, the proposed MA greatly improved its performances in several aspects of absorption bandwidth, tunable range, simple structure and small volume. Increasing the VO2 conductivity from 200 S/m to 2×105 S/m, the absorption rate of proposed MA rapidly increases from 1.2% to 99.2%, thus the proposed MA has the high tuning performance with maximum modulation depth of 98.8%. We also investigate the absorption origin of proposed MA by using the electric field distributions. The proposed MA achieves the ultra-broadband absorption by the fundamental resonance and high-order resonances of hollow fan VO2 pattern. In addition, all the influences of polarization angle, incidence angle and geometrical parameters on the ultra-broadband absorption are analyzed in detail. Our designed MA may be widely utilized for practical applications of THz technology.

VL  - 13
IS  - 3
ER  -

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Author Information

In-Ho Pak

Institute of Natural Science, University of Sciences, Pyongyang, Democratic People’s Republic of Korea

http://orcid.org/0009-0002-3832-3238
Hyok-Ju Kim

Department of Physics, University of Sciences, Pyongyang, Democratic People’s Republic of Korea

http://orcid.org/0009-0000-1051-4679
Kwang-Jin Ri

Department of Physics, University of Sciences, Pyongyang, Democratic People’s Republic of Korea

Contact Email

http://orcid.org/0009-0002-2603-2724
Song-Il Ri

Institute of Natural Science, University of Sciences, Pyongyang, Democratic People’s Republic of Korea

http://orcid.org/0009-0007-7947-8224

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APA Style

Pak, I., Kim, H., Ri, K., Ri, S. (2025). Ultra-broadband Tunable Terahertz Absorber Based on Hollow Fan Patterned VO2 Metamaterials. Science Journal of Analytical Chemistry, 13(3), 22-30. https://doi.org/10.11648/j.sjac.20250902.12

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ACS Style

Pak, I.; Kim, H.; Ri, K.; Ri, S. Ultra-broadband Tunable Terahertz Absorber Based on Hollow Fan Patterned VO2 Metamaterials. Sci. J. Anal. Chem. 2025, 13(3), 22-30. doi: 10.11648/j.sjac.20250902.12

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AMA Style

Pak I, Kim H, Ri K, Ri S. Ultra-broadband Tunable Terahertz Absorber Based on Hollow Fan Patterned VO2 Metamaterials. Sci J Anal Chem. 2025;13(3):22-30. doi: 10.11648/j.sjac.20250902.12

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@article{10.11648/j.sjac.20250902.12,
  author = {In-Ho Pak and Hyok-Ju Kim and Kwang-Jin Ri and Song-Il Ri},
  title = {Ultra-broadband Tunable Terahertz Absorber Based on Hollow Fan Patterned VO2 Metamaterials
},
  journal = {Science Journal of Analytical Chemistry},
  volume = {13},
  number = {3},
  pages = {22-30},
  doi = {10.11648/j.sjac.20250902.12},
  url = {https://doi.org/10.11648/j.sjac.20250902.12},
  eprint = {https://article.sciencepublishinggroup.com/pdf/10.11648.j.sjac.20250902.12},
  abstract = {A novel design of ultra-broadband tunable terahertz (THz) absorber based on hollow fan patterned VO2 metamaterials is proposed and investigated. Our designed metamaterial absorber (MA) is aimed at expanding the absorption bandwidth, simplifying the structure and reducing the volume as much as possible. It is really proved from simulation results that the proposed MA has not only simple structure and small volume but also ultra-broadband absorption above 90% ranging from 2.92 THz to 10.05 THz. Comparing with previous studies, the proposed MA greatly improved its performances in several aspects of absorption bandwidth, tunable range, simple structure and small volume. Increasing the VO2 conductivity from 200 S/m to 2×105 S/m, the absorption rate of proposed MA rapidly increases from 1.2% to 99.2%, thus the proposed MA has the high tuning performance with maximum modulation depth of 98.8%. We also investigate the absorption origin of proposed MA by using the electric field distributions. The proposed MA achieves the ultra-broadband absorption by the fundamental resonance and high-order resonances of hollow fan VO2 pattern. In addition, all the influences of polarization angle, incidence angle and geometrical parameters on the ultra-broadband absorption are analyzed in detail. Our designed MA may be widely utilized for practical applications of THz technology.
},
 year = {2025}
}

Copy | Download

TY  - JOUR
T1  - Ultra-broadband Tunable Terahertz Absorber Based on Hollow Fan Patterned VO2 Metamaterials

AU  - In-Ho Pak
AU  - Hyok-Ju Kim
AU  - Kwang-Jin Ri
AU  - Song-Il Ri
Y1  - 2025/11/14
PY  - 2025
N1  - https://doi.org/10.11648/j.sjac.20250902.12
DO  - 10.11648/j.sjac.20250902.12
T2  - Science Journal of Analytical Chemistry
JF  - Science Journal of Analytical Chemistry
JO  - Science Journal of Analytical Chemistry
SP  - 22
EP  - 30
PB  - Science Publishing Group
SN  - 2376-8053
UR  - https://doi.org/10.11648/j.sjac.20250902.12
AB  - A novel design of ultra-broadband tunable terahertz (THz) absorber based on hollow fan patterned VO2 metamaterials is proposed and investigated. Our designed metamaterial absorber (MA) is aimed at expanding the absorption bandwidth, simplifying the structure and reducing the volume as much as possible. It is really proved from simulation results that the proposed MA has not only simple structure and small volume but also ultra-broadband absorption above 90% ranging from 2.92 THz to 10.05 THz. Comparing with previous studies, the proposed MA greatly improved its performances in several aspects of absorption bandwidth, tunable range, simple structure and small volume. Increasing the VO2 conductivity from 200 S/m to 2×105 S/m, the absorption rate of proposed MA rapidly increases from 1.2% to 99.2%, thus the proposed MA has the high tuning performance with maximum modulation depth of 98.8%. We also investigate the absorption origin of proposed MA by using the electric field distributions. The proposed MA achieves the ultra-broadband absorption by the fundamental resonance and high-order resonances of hollow fan VO2 pattern. In addition, all the influences of polarization angle, incidence angle and geometrical parameters on the ultra-broadband absorption are analyzed in detail. Our designed MA may be widely utilized for practical applications of THz technology.

VL  - 13
IS  - 3
ER  -

Copy | Download