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![Application of Metamaterials
Fig 2a. super lens imaging [6] Fig 2b. cloaking [7]
Fig 2c. tunable MTMs [8]
1) N.Fang, H.Lee, C.Sun, and X.Zhang, “Sub–Diffraction-Limited Optical Imaging with a Silver
Superlens”, Science, Vol. 308, no. 5721, pp. 534-537,April 2005.
2) S.A.Cummer, B.I.PopaD.Schurig, D.R.Smith, and J.B.Pendry, “Full-wave simulations of
electromagnetic cloaking structures”, Phys. Rev. Lett. (E), Vol. 74, pp. 036621,May 2006.
3) M.Lapline, “Tunable metamaterials: the key step to practical application”, (Online web page, SPIE
Newsroom, 2009.](https://image.slidesharecdn.com/preregistrationviva-231013062002-0cd253d1/85/metamaterial-6-320.jpg)
![Metamaterial Based Absorber
• Artificial effective homogeneous structures with unusual electromagnetic properties
characterized by the effective permittivity (εeff) and permeability (µeff) which measure the
effects of electric and magnetic field on and by the medium by suitably adjusting its structural
parameters..
• The structure of the MA is basically composed of unit cells arranged in a periodic manner.
The structure consists of a top conducting layer and a bottom ground plane isolated by a
dielectric interlayer.
Fig (3)
Fig4. metamaterial perfect absorber made of electric/magnetic metasurface on top of a metallic ground
plate. Reproduced from the reference [9]
.
Introduction Contd …](https://image.slidesharecdn.com/preregistrationviva-231013062002-0cd253d1/85/metamaterial-8-320.jpg)
![Absorption in Metamaterial
When an electromagnetic wave is incident upon a metamaterial structure, the electric field is
coupled with the top metallic structure and controls the electric permittivity (εr). The counter
propagating circulating currents at the top and the bottom ground layers couples with the
magnetic field and controls the magnetic permeability (µr) of the structure. Therefore, by
optimizing the physical parameters of the top metal layer and the thickness of the dielectric
substrate, the electric and magnetic fields can be effectively coupled in a specific frequency
range where the input impedance Z (ω) can be matched with free space impedance (Z0) at the
interface resulting minimization of S11 of the structure
Reproduced from reference [10]
Introduction Contd …
𝐴 𝑤 = 1 − |𝑆11|2 − |𝑆21|2
= 1 − |𝑆11|2
𝑆11 =
𝑍 𝑤 − ηo
𝑍 𝑤 + ηo
|𝑆21|2 =0
Z(w)=ηo
(1 + 𝑆11)2 − S2
21
(1 − 𝑆11)2 − S2
21](https://image.slidesharecdn.com/preregistrationviva-231013062002-0cd253d1/85/metamaterial-9-320.jpg)
![Development in Metamaterial based application
Fig 4 Current trends in metasurface absorber. Reproduced from reference [11]
Introduction Contd …](https://image.slidesharecdn.com/preregistrationviva-231013062002-0cd253d1/85/metamaterial-10-320.jpg)
![Indium Antimoninde (InSb)
• Semiconductor material from III-V group
• Band gap 1.44ev
• Thermally tuning medium as its electromagnetic properties are very sensitive to
temperature.
• The complexed value of permittivity of InSb is temperature dependent given by Drude
model [48-49];
𝜀 𝑤 = ε∞− ω2
p/(ω2+iωϒ)
where, ε∞ =high freq. permittivity
ϒ= damping constant
ω= angular frequency
ωp= plasma frequency](https://image.slidesharecdn.com/preregistrationviva-231013062002-0cd253d1/85/metamaterial-42-320.jpg)
![Strontium Titanate (STO)
• Incipient ferroelectric materials
• Dielectric material having unique properties including high dielectric constant, low
dielectric loss, superior insulation, and good chemical stability .
• The most attractive property is that the high dielectric constant of the STO can be
adjusted dynamically by varying external environment temperature or by changing
the applied electric field.
• The permittivity of STO can be calculated by [50];
𝜀 𝑤 = ε∞− F/(𝑘0
2
- 𝑘2 −i 𝑘ϒ)
where, ε∞ =high freq. permittivity=9.6
F(cm-2)= 2.3*106
ko (cm-1) = soft mode wave no
ϒ(cm-1)= damping constant
The relationship between soft mode wave number k0 and damping constant γ with the
external temperature can be expressed as follows:
ϒ 𝑇 = −3.3 + 0.094𝑇
𝑘0 𝑇 = 31.2(𝑇 − 42.5)](https://image.slidesharecdn.com/preregistrationviva-231013062002-0cd253d1/85/metamaterial-43-320.jpg)
![Temperature dependent permittivity of STO
Real and imaginary value of relative permittivity has been obtained using MATLAB
software [51]
Fig 15a. real part of permittivity of STO with
different temperatures and frequencies
Fig 15b. imaginary part of permittivity of STO with
different temperatures and frequencies](https://image.slidesharecdn.com/preregistrationviva-231013062002-0cd253d1/85/metamaterial-44-320.jpg)
![Germanium Antimont Telluride (Ge-Sb-Te)
• Phase change material
• Two states: amorphous and crystalline with different electromagnetic characteristics
• The crystallization temp. of GST is 1600c and melting temp. is 6000c.
• GST-based systems provide nearly perfect absorption in the IR and visible light regimes
• Refractive index of GSTs is wavelength-dependent and Dielectric constant of GST is given by
[52-53]:
𝜀𝑥 − 1
𝜀𝑥 + 2
= 𝑥
𝜀𝑐 − 1
𝜀𝑐 + 2
+ 1 − 𝑥
𝜀𝑎 − 1
𝜀𝑎 + 2
where εc = 6.3 & εa = 4.3 are dielectric constant of crystalline (x=1) and
amorphous (x=0) states
GST alloys are known to have advantages over other phase changing material having relatively
lower dissipative loss in near infra red regime and nonvolatility i.e. preserving the
amorphous/crystalline state even in the absence of the input power
• Tunable metamaterials can be realized by the material crystalline phase change, which leads
to the change of dielectric properties. The crystalline phase transition leads to electrical and optical
property changes such as resistivity, color, and refractive indices](https://image.slidesharecdn.com/preregistrationviva-231013062002-0cd253d1/85/metamaterial-45-320.jpg)
![Graphene
• Graphene, a two-dimensional version of graphite, consists of
a planar atomic layer of carbon atoms bonded in a hexagonal structure.
• Thinnest material having unique property such as optical transparency, flexibility,
high electron mobility .
• Graphene sheet can be managed to have a great conductivity amount due to its high
electron mobility. The electron mobility of this platform can be adjusted either by
chemical doping or gate voltage to produce desired conductivity in the frequency
region of interest
Fig 17. hexagonal lattice of graphene
• Permittivity of graphene given as: [54-55]
𝜀𝑔= 1+i
𝑁𝜎
𝑤𝜀0𝑡𝑔
Where, N =the number of graphene layers
tg= thickness of the graphene plate
ɛ0= permittivity of vacuum
σ = conductivity of graphene](https://image.slidesharecdn.com/preregistrationviva-231013062002-0cd253d1/85/metamaterial-46-320.jpg)
More Related Content
metamaterial
- 1. Pre-Registration Seminar On Presented By NehaNiharika Roll No:185EC16 Department of Electronics and Communication Engineering National Institute of Technology Patna 800005 Under the Supervision of Dr. Sangeeta Singh Tunable Terahertz Devices
- 2. 2 Outline Introduction Metamaterialbased absorber Literature review Problem identification Approaches to be followed Implementation of paper Future work References
- 3. Introduction to Metamaterials Aperiodic material that derives its properties from its structure rather than its components. Fig 1a Fig 1b
- 4. • “Meta-” means“altered, changed” or “higher, beyond” • Existing materials only exhibit a small subset of electromagnetic properties theoretically available • Metamaterials can have their electromagnetic properties altered to something beyond what can be found in nature. • Can achieve negative index of refraction, zero index of refraction, magnetism at optical frequencies, etc. • “Metamaterial” coined in the late 1990’s Introduction to Metamaterials
- 5. Historical overview ofMetamaterial • 1948: E.Kock tailored εeff and µeff by periodically arranging the conducting disks, strips and spheres • 1968: Veselgo predicted the existance of LHM • 1996:realization of negative permittivity practically by Pendry • 2001:First experimental demonstration of LHM by Smith Introduction Contd … • 1999: realization of negative permeability practically by Pendry
- 6. Application of Metamaterials Fig2a. super lens imaging [6] Fig 2b. cloaking [7] Fig 2c. tunable MTMs [8] 1) N.Fang, H.Lee, C.Sun, and X.Zhang, “Sub–Diffraction-Limited Optical Imaging with a Silver Superlens”, Science, Vol. 308, no. 5721, pp. 534-537,April 2005. 2) S.A.Cummer, B.I.PopaD.Schurig, D.R.Smith, and J.B.Pendry, “Full-wave simulations of electromagnetic cloaking structures”, Phys. Rev. Lett. (E), Vol. 74, pp. 036621,May 2006. 3) M.Lapline, “Tunable metamaterials: the key step to practical application”, (Online web page, SPIE Newsroom, 2009.
- 7. • Terahertz radiation,also called submillimeter radiation, terahertz waves, terahertz light, T-rays, T-waves, T-light, T-lux, or THz • consists of electromagnetic waves at frequencies from 0.3 to 10 terahertz (THz). • The term applies to electromagnetic radiation with frequencies between the high-frequency edge of the millimeter wave band, 300 GHz and the low frequency edge of the far-infrared light band, 3000 GHz. • Some of the application Terahertz devices: Absorber Polarizer Transmitter Sensor etc Terahertz Devices
- 8. Metamaterial Based Absorber •Artificial effective homogeneous structures with unusual electromagnetic properties characterized by the effective permittivity (εeff) and permeability (µeff) which measure the effects of electric and magnetic field on and by the medium by suitably adjusting its structural parameters.. • The structure of the MA is basically composed of unit cells arranged in a periodic manner. The structure consists of a top conducting layer and a bottom ground plane isolated by a dielectric interlayer. Fig (3) Fig4. metamaterial perfect absorber made of electric/magnetic metasurface on top of a metallic ground plate. Reproduced from the reference [9] . Introduction Contd …
- 9. Absorption in Metamaterial Whenan electromagnetic wave is incident upon a metamaterial structure, the electric field is coupled with the top metallic structure and controls the electric permittivity (εr). The counter propagating circulating currents at the top and the bottom ground layers couples with the magnetic field and controls the magnetic permeability (µr) of the structure. Therefore, by optimizing the physical parameters of the top metal layer and the thickness of the dielectric substrate, the electric and magnetic fields can be effectively coupled in a specific frequency range where the input impedance Z (ω) can be matched with free space impedance (Z0) at the interface resulting minimization of S11 of the structure Reproduced from reference [10] Introduction Contd … 𝐴 𝑤 = 1 − |𝑆11|2 − |𝑆21|2 = 1 − |𝑆11|2 𝑆11 = 𝑍 𝑤 − ηo 𝑍 𝑤 + ηo |𝑆21|2 =0 Z(w)=ηo (1 + 𝑆11)2 − S2 21 (1 − 𝑆11)2 − S2 21
- 10. Development in Metamaterialbased application Fig 4 Current trends in metasurface absorber. Reproduced from reference [11] Introduction Contd …
- 11. STATE OF ART: Variousstudies have been done for enhancement of bandwidth absorption of metamaterial and one of the approach is frequency tunable metamaterial and this can be done by using the material whose property can be tuned according to the requirement rather than making changes in geometry of absorber. Some of the approaches are: • Tuning via thermo-optic effect. • Tuning via free carrier effects • Tuning via Phase Transition material • Chalcogenide glass. • Graphene.
- 12. Tuning via PhaseTransition material TOPIC AUTHORS YEAR OF PUBLICATION OBSERVATION A tunable hybrid metamaterial absorber based on vanadium oxide films Qi-Ye Wen, Huai-Wu Zhang, Qing-Hui Yang, Zhi Chen, Yang Long, Yu-Lan Jing, Yuan Lin and Pei-Xin Zhang Journal of Physics :D Applied Physics (2012) Amplitude and frequency of the device has been tuned by make phase transition of V02. Switchable and tunable metamaterial absorber in THz frequencies Dang Hong Luu, Nguyen Van Dung, Pham Hai, Trinh Thi Giang, Vu Dinh Lam Journal of Science: Advanced Materials and Devices (2016) The absorption intensity and absorption frequency has been tuned with modification of the conductivity of V02 while the absorption frequency is tuned by changing the temperature of InSb material filled into two slits of SRR. • Vanadium Oxide (Vo2)
- 13. TOPIC AUTHORS YEAROF PUBLICATION OBSERVATION Development of a tunable terahertz absorber based on temperature control Liu Jianjun ,Fan Lanlan Microwave and Optical Technolgy Letters (2019) Phase transition of thermally triggered VO2 thin films is used to control the absorption rate of metamaterial absorber Study on Temperature Adjustable Terahertz Metamaterial Absorber Based on Vanadium Dioxide Yubing Zhang , Pinghui Wu , Zigang Zhou , Xifang Chen , Zao Yi , Jiayi Zhu , Tiansheng Zhang , and Huge Jile 2020 three tunable terahertz metamaterial absorbers based on VO2 were designed, providing flexible control over the absorption performance
- 14. TOPIC AUTHORS YEAROF PUBLICATION OBSERVATION Tunable broadband terahertz metamaterial absorber using multi-layer black phosphorus and vanadium dioxide Tongling Wang , Lizhi Qu , Lingfei Qu , Yuping Zhang , Huiyun Zhang and Maoyong Cao Journal of Physics D: Applied Physics (2020) The proposed device uses two independently controllable methods to achieve absorption tuning from 34.64 to 98.8% and from 8 to 98.8% by adjusting the electron doping of BP and conductivity of Vo2 Dual-controlled switchable broadband terahertz absorber based on a graphene- vanadium dioxide metamaterial Tongling Wang, Yuping Zhang, Huiyun Zhang, and Maoyong Cao Optical Material Express (2020) A dual-controlled switchable broadband terahertz (THz) metamaterial absorber which shows tuning of absorptance from 26 to 99.2% by varying the graphene Fermi energy and from 9 to 99.2% by increasing the conductivity of the VO2.
- 15. Switchable and tunablemetamaterial absorber in THz frequencies Luu, Dang Hong; Van Dung, Nguyen; Hai, Pham; Giang, Trinh Thi; Lam, Vu Dinh “Switchable and tunable metamaterial absorber in THz frequencies”, Journal of Science: Advanced Materials and Devices, 1(1), 65–68 (2016) Fig 5a. schematic diagram of MMA structure Fig 5b. absorption spectra of MM structure with different conductivity values of VO2 film. Fig 5c. schematic diagram of MMA structure with InSb filled Fig 5d. the simulated absorption spectra of MMA structure with different temperature
- 16. Dual-controlled switchable broadbandterahertz absorber based on a graphene-vanadium dioxide metamaterial Wang, Tongling; Zhang, Yuping; Zhang, Huiyun; Cao, Maoyong “Dual-controlled switchable broadband terahertz absorber based on a graphene-vanadium dioxide metamaterial” Optical Materials Express, 10(2), 369 (2020) • To achieve dynamically dual-controlled switchable broadband Thz absorptance, metamaterials with both graphene and Vo2 has combined. Fig 6a. schematic of graphene and Vo2 -based metamaterial broadband absorber Fig 6b. absorptance spectra of the proposed absorber at various VO2 conductivities Fig 6c. absorptance spectra of the proposed absorber at various fermi energy of Graphene
- 17. • Liquid Crystal LCis probably the most widely used active material in optics. Its large optical birefringence, which can be controlled by thermal or electrical stimuli, makes it an obvious potential option as a tuning medium for metasurfaces TOPIC AUTHORS YEAR OF PUBLICATIO N OBSERVATION Liquid Crystal Tunable Metamaterial Absorber David Shrekenhamer, Wen-Chen Chen, and Willie J. Padilla Physical Review Letter (2013) Incorporation of active liquid crystal into strategic locations within the metamaterial unit cell, absorption has been tuned. Terahertz characterization of tunable metamaterial based on electrically controlled nematic liquid crystal Rafał Kowerdziej, Marek Olifierczuk, Janusz Parka, and Jerzy Wróbel Applied Physics (2014) The proposed tuning system is based on the use of the NLC. Its properties can be controlled by reorienting the LC molecular direction with the application of bias voltage.
- 18. TOPIC AUTHORS YEAROF PUBLICATION OBSERVATION A Tunable Metamaterial Absorber Based on Liquid Crystal Intended for F Frequency Band Guangsheng Deng, Tianyu Xia, Shuaicheng Jing, Jun Yang, Hongbo Lu, and Zhiping Yin IEEE Antenna and Propagation Letter (2017) The orientation of the liquid crystal molecules can be macroscopically controlled by voltage between top metal pattern layer and metal ground. Thus, the permittivity of the LC layer, dynamically changed which helps in tuning of absorption frequency. Electrically tunable terahertz dual-band metamaterial absorber based on a liquid crystal Zhiping Yin, Yujiao Lu, Tianyu Xia, Weien Lai, Jun Yang, Hongbo Lu and Guangsheng Deng Royal Society of Chemistry (2018) A liquid crystal (LC) based tunable metamaterial absorber with dual-band absorption is presented which shows frequencies can be dynamically tuned by adjusting the bias voltage of the LC layer
- 19. TOPIC AUTHORS YEAROF PUBLICATION OBSERVATION Fast-Tunable Terahertz Metamaterial Absorber Based on Polymer Network Liquid Crystal Jhiping Yin , Chaofan Wan , Guangsheng Deng, Andong Zheng, Peng Wang, Yang Yang, Sheng Gao, Jun Yang, Fei Cai , Zelun Li and Hongbo Lu Applied Science (2018) A tunable metamaterial absorber (MA) based on polymer network liquid crystal (PNLC) in the terahertz (THz) frequency band. Under the optimal polymerization condition, through electrical control of the orientation of the PNLC embedded in the frequency selective surface, the resonant frequency of the absorber can be tuned
- 20. Electrically tunable terahertzdual-band metamaterial absorber based on a liquid crystal Zhiping Yin, Yujiao Lu, Tianyu Xia, Weien Lai, Jun Yang, Hongbo Lu and Guangsheng Deng “ Electrically tunable terahertz dual-band metamaterial absorber based on a liquid crystal” Royal Society of Chemistry 4197-4023 (2018) Fig 7a. schematic of a unit cell of the proposed tunable dual- band metamaterial absorber based on the liquid crystal. Fig 7b. absorption spectrum of the proposed metamaterial absorber
- 21. A Tunable MetamaterialAbsorber Based on Liquid Crystal Intended for F Frequency Band Guangsheng Deng, Tianyu Xia, Shuaicheng Jing, Jun Yang, Hongbo Lu, and Zhiping Yin “A Tunable Metamaterial Absorber Based on Liquid Crystal Intended for F Frequency Band” IEEE Antenna and Wireless Propagation Letter (16) (2017) (c) Fig 8c. measured absorptivity for different bias voltage Fig 8b. simulated spectra of absorptivity with no bias and fully bias voltage Fig 8a. schematic of LC based absorber
- 22. • Chalcogenide Glasses Amongvarious kinds of nonvolatile PCMs, ChGs such as germanium–antimony–tellurium (GST) are the most common choice in photonic applications for their quick responses to external stimuli and reliable data retentions TOPIC AUTHORS YEAR OF PUBLICATION OBSERVATION A Switchable Mid‐Infrared Plasmonic Perfect Absorber with Multispectral Thermal Imaging Capability Andreas Tittl, Ann Katrinn U, Michel Martin, Xinghui Yin, Behrad Golipur and Harald Geissien Advanced Material (2015) Utilizing the amorphous‐to‐crystalline phase transition in GST, the proposed structure offers switchable absorption with strong reflectance contrast at resonance and large phase‐change‐induced spectral shifts
- 23. TOPIC AUTHORS YEAROF PUBLICATI ON OBSERVATION Dynamic Thermal Emission Control Based on Ultrathin Plasmonic Metamaterials Including Phase- Changing Material GST Yurui Qu, Qiang Li, Kaikai Du, Lu Cai, Jun Lu, and Min Qiu Laser & Photonics (2017) An ultrathin plasmonic thermal emitter is experimentally demonstrated to dynamically control thermal emission with low- power-consumption. The dynamic low-power- consumption control is implemented by incorporating phase- changing material Ge2Sb2Te5 (GST), Tunable near- infrared perfect absorber based on the hybridization of phase-change material and nanocross-shaped resonators Ce Li, Wei Zhu, Zhe Liu, Shi Yan, Ruhao Pan, Shuo Du, Junjie Li, and Changzhi Gu Applied Physics Letter (2018) A tunable GST-based MPA in the near infrared region was demonstrated. Dielectric environment engineering, which is equivalent to tuning the permittivity of the capacitance of the LC circuit result in the change of resonance.
- 24. TOPIC AUTHORS YEAROF PUBLICATION OBSERVATION Near-field imaging of the multi-resonant mode induced broadband tunable metamaterial absorber Lulu Chen, Liaoxin Sun, Hongxing Dong, Nanli Mou, Yaqiang Zhan, Qisong Li, Xiongwei Jiang and Long Zhang Royal Society of Chemistry (2019) The proposed absorber shows the dynamic tunability due to the phase change of ultrathin GST layer. The absorptive wavelength will shift to longer wavelength after converting the GST thin film from amorphous to crystalline phase Tunable perfect absorber based on gold grating including phase-c hanging material in visible range Lei Zhang, Ying Wang, Le Zhou, Fang Chen Applied Physics (2019) A tunable GST-based gold grating structure which show the absorption can be dynamic controlled by inserting phase- changing material.
- 25. TOPIC AUTHORS YEAROF PUBLICATION OBSERVATION Large-scale, low- cost, broadband and tunable perfect optical absorber based on phase change material Nanli Moua,b, Xiaolong Liuc Tao Weia , Hongxing Donga , Qiong Hed,e, Lei Zhoud,e, Yaqiang Zhanga,Long Zhanga and Shulin Sunc Royal Society of Chemistry (2020) broadband, polarization- insensitive and tunable optical metamaterial absorber which utilise the optical properties of the PCMs tune the working band of the proposed metamaterial absorber via varying temperature,
- 26. Tunable near-infrared perfectabsorber based on the hybridization of phase-change material and nanocross-shaped resonators Fig 9a schematic of nanocross-shaped MPA and the incident light polarization configuration. 9b and 9c top view and side view of the MPA unit cell (c) experimental and simulated performance , the black line and the red line are the reflection and absorption spectra, respectively Fig 9a Fig 9b Fig 9c Ce Li, Wei Zhu, Zhe Liu, Shi Yan, Ruhao Pan, Shuo Du,Junjie Li, and Changzhi Gu “Tunable near-infrared perfect absorber based on the hybridization of phase-change material and nanocross-shaped resonator” Applied Phys. Lett. 113, 231103 (2018)
- 27. • Strontium Titanate TOPICAUTHORS YEAR OF PUBLICATION OBSERVATION Thermal tunability in terahertz metamaterials fabricated on strontium titanate single-crystal substrates Ranjan Singh Abul K. Azad Q. X. Jia Antoinette J. Tayloran Hou- Tong Chen Optics Letters (2011) A planar gold SRR array fabricated on single-crystal bulk STO shows the resonant behavior in Thz freq range with the variation in temperature Frequency tunable metamaterial absorber at deep- subwavelength scale Ben-Xin Wang, Xiang Zhai,Gui- Zhen Wang, Wei-Qing Huang and Ling-Ling Wang Optic Express (2014) A frequency tunable and deep- subwavelength scale terahertz metamaterial absorber formed by a square metallic patch and a strontium titanate dielectric layer on top of a ground plane which shows The shift of the resonance frequency is attributed to the temperature-dependent refractive index of the dielectric layer
- 28. TOPIC AUTHORS YEAROF PUBLICATION OBSERVATION Tunable silicon-based all-dielectric metamaterials with strontium titanate thin film in terahertz range Yanjiao Zhao, Baiwei Li, Chuwen Lan, Ke bi, and Zhaowei Qu Optic Express (2017) A tunable silicon all-dielectric metamaterials in THz ranges by covering the SAMs with a layer of STO showing the resonance frequencies is tuned on the basis of temperature dependent complex relative permittivity. Bi-tunable terahertz absorber based on strontium titanate and Dirac semimetal C. Kadalec, V.Sokoromets, F.Kadlec, H.Nemec, H.Chen, V.Jurka, K. Hruška and P.Kužel Journal of Physics D: Applied Physics Year (2018) A frequency-tunable metamaterial in the THz range, consisting of metallic subwavelength resonators patterned on an active thin layer of strained SrTiO3 which shows a resonance near 0.5 THz, which is determined both by the geometric shape of the resonators and by the permittivity of the active layer .
- 29. TOPIC AUTHORS YEAROF PUBLICATIO N OBSERVATION Metamaterial absorber with independently tunable amplitude and frequency in the terahertz regime Xin Huang, Fan Yang, Bing Gao, Qi Yang, Jiamin Wu, and Wei He Optics Express (2019) Effective combination of graphene and strontium titanate (STO) in one metamaterial structure, the tunable properties of the amplitude and center frequency are implemented. The amplitude can be tuned by adjusting the chemical potential of graphene sheet, and center frequency can get a shift through temperature changes in the STO material Bi-tunable terahertz absorber based on strontium titanate and Dirac semimetal Han xiong, Yuehong Peng, Fan Yang Zhijing Yang, and Zhenni Wang Optics Express (2020) A polarization-insensitive absorber based on strontium titanate (STO) and bulk Dirac semimetal (BDS) in the terahertz (THz) region. The center frequency of the absorption peak can be independently regulated by temperature or Fermi energy level of STO or BDS, respectively
- 30. Thermally tunable metamaterialabsorber based on strontium titanate in the terahertz regime Xin Huang, Wei He, Fan Yang, Jia Ran, Qi Yang and Shengyi Xie “Thermally tunable metamaterial absorber based on strontium titanate in the terahertz regime” optical materials express 1377, vol 9 (2019) Fig 10a. schematic of the absorber (c) Fig 10c. absorption spectra of absorber with different temperature Fig 10b. absorption spectra under normal incidence at temp 400k
- 31. Metamaterial absorber withindependently tunable amplitude and frequency in the terahertz regime Xin huang, Fan yang, Bing gao, Qi yang, Jiamin Wu, and Wei He “Metamaterial absorber with independently tunable amplitude and frequency in the terahertz regime” Optics Express Vol.19 (2019) Fig 11b. central frequency tunable spectra by changing temperature Fig 11a. schematic representation (top view) of unit cell Fig 11c. amplitude tunable spectra under different chemical potential
- 32. Tuning via Free-CarrierEffects According to the Drude model, plasma frequencies, and thus refractive indices of semiconductors can be tuned by altering their carrier densities and effective masses. TOPIC AUTHORS YEAR OF PUBLICATI ON OBSERVATION Thermal broadband tunable Terahertz metamaterials Jun Zhu, Jiaguang Han ,Zhen Tian , Jianqiang Gu , Zhongyong Chen, Weili Zhang Optics Communication (2011) Incorporation of the semiconductor into the gap of metallic SRRs, where precise patterning of semiconductors permits frequency tuning of the metamaterial resonance by changing the external temperature Temperature tunable metamaterial absorber at THz frequencies Ben-Xin Wang, · Gui-Zhen Wang Journal Material Science (2017) A wide frequency tunable range of terahertz absorber formed by a metallic patch resonator and a metallic board spaced by an InSb dielectric layer is demonstrated. The frequency of the absorber can be tuned actively by varying the temperature of the absorber, and finally a 80.4% frequency tuning rang is obtained.
- 33. TOPIC AUTHORS YEAROF PUBLICATION OBSERVATION InSb-Enhanced Thermally Tunable Terahertz Silicon Metasurfaces Daquan Yang , Chao Zhang , Xiaogang Li , and Chuwen Lan IEEE Access (2019) Thermally tunable THz all- dielectric grating structure consists of two dielectric layers in which the posterior is silicon grating and the former is InSb thin film. The thermal tunability of the grating structure is also dependent on the temperature and thickness of the InSb thin film, which we can speculate from the enhanced frequency shift in the absorber structure Design of a six- band terahertz metamaterial absorber for temperature sensing application Haijun Zou, Yongzhi Cheng Optics Material (2019) A six-band terahertz MMA, which consists of a metallic cross-cave- patch (CCP) structure array and an InSb dielectric substrate layer backed by a ground-plane which shows tuning of resonance frequency is achieved using temperature dependent refractive material Insb
- 34. TOPIC AUTHORS YEAROF PUBLICATION OBSERVATION Thermally tunable terahertz metasurface absorber based on all dielectric indium antimonide resonator structure Hao Luo, Yongzhi cheng Optical materials (2020) A novel design of temperature tunable metasurface absorber (MSA) based on all dielectric indium antimonide (InSb) resonator structure in terahertz (THz) regionhe is proposed in which dielectric property of the InSb can be actively adjusted through the external environment heat with different temperature. Temperature Tunable Seven Band Terahertz Metamaterial Absorber Using Slotted Flower– Shaped Resonator on an InSb Substrate Bhargav Appasani Plasmonics (2021) A seven-band temperature tunable terahertz metamaterial absorber is proposed, whose unit cell consists of a slotted flower–shaped resonator (S-FSR) on InSb dielectric substrate which shows temperature tenability is because of the changes in the plasma frequency of the dielectric.
- 35. Thermal broadband tunableTerahertz metamaterials Jun Zhu, Jiaguang Han, Zhen Tian, Jianqiang Gu, Zhongyong Chen , Weili Zhang “Thermal broadband tunable Terahertz metamaterials” Optics Communications 284 3129–3133 (2011) (c) Fig 12a. unit cell of proposed absorber Fig 12b. Simulated transmission with quartz substrate Fig 12c. Simulated transmission with sillicon substrate
- 36. • Graphene Graphene, atwo-dimension material consisting of one monolayer of carbon atoms, has been recently applied in electronic and photonic devices due to its exotic properties, such as optical transparency, flexibility, high electron mobility.In addition, its sheet conductivity can be continuously tuned in a broad frequency range by shifting the electronic Fermi level via chemical or electronic doping, which enables fast electrical modulation and on-chip integration.This makes the continuous or structured graphene sheet a promising candidate for designing tunable THz metamaterial. TOPIC AUTHORS YEAR OF PUBLICATION OBSERVATION Tunable THz perfect absorber using graphene-based metamaterials Mahboobeh Faraji, Mohammad Kazen, Moravvej Farshi and Leila Yousefi Optics Communication (2015) Tunable and switchable absorber using two patterned graphene layers (i.e., fishnet plus microribbons) both in one unit cell shows perfect absorbances of 96–99% obtained at various frequencies centered about 2.14–9.94 TH
- 37. TOPIC AUTHORS YEAROF PUBLICATION OBSERVATION A Tunable Ultrabroadband Ultrathin Terahertz Absorber Using Graphene Stacks Yanfei Dong, Peiguo Liu, Dingwang Yu, Gaosheng Li and Liang Yang IEEE Antenna and Wireless Propagation Letter (2016) dynamic tuning of the absorption band, is achieved by combining two concentric circular split-rings encircling a split circular resonator with graphene stacks embedded in a SiO 2 dielectric. the frequency response can be dynamically tuned by varying the graphene gate voltage to reduce the need for complex bias network Based on graphene tunable dual-band terahertz metamaterial absorber with wide- angle Mulin Huang, Yongzhi Cheng, Zhengze Cheng, Haoran Chen, Xuesong Mao and Rongzhou Gong Optics Communication (2018) A tunable MMA based on the SGP for THz waves, which yields dual-band and wide-angle absorption properties has been demonstrated .
- 38. TOPIC AUTHORS YEAROF PUBLICATION OBSERVATION Ultra-thin and broadband tunable metamaterial graphene absorber Han Xiong, Ying- Bo Wu, Ji Dong, Ming-Chun Tang, Yan-Nan Jiang, and Xiao-Ping Zeng Optics Express (2018) an ultra-thin and broadband metamaterial absorber which is frequency tuned by graphene in the far-infrared region is designed. By varying an external bias voltage applied to the graphene and geometric size of each patch, absorption band and spectral position of the proposed absorber can be controlled The design of a graphene-based wideband tunable metamaterial absorber in THz regime. L Wang, C Ding, D Xia, X Ding and Y Wang IOP Conference series: Material series & Engineering (2019) A wideband tunable MMA based on graphene in Terahertz regime using a single layer of multiple split- ring resonators (SRRs) has been demonstrated
- 39. TOPIC AUTHORS YEAROF PUBLICATION OBSERVATION Graphene-based dual- band tunable perfect absorber in THz range Zhaoyang Liu, Jian Li, Lingjuan He and Tianbo Yu 2021 Absorber is composed of a circular graphene layer with an ellipse cut out in the centre, separated by a dielectric layer in the middle and a gold mirror at the bottom. position of the absorption peak can be changed by adjusting the Fermi level and geometric parameters of the graphene pattern. Furthermore, the absorber is insensitive to the polarized incident light with a wide incident angle. Tunable terahertz perfect absorber with a graphene-based double split-ring structure Zhendong Wu, Bijun Xu, Mengyao Yan, Bairui Wu, Pan cheng and Zhichao Sun Optical Material Express (2021) The impact of different Fermi energies and the disparate relaxation times on the regulation of absorption along with the optimal structure parameters has been explored required to achieve perfect absorption.
- 40. Based on graphenetunable dual-band terahertz metamaterial absorber with wide-angle M.Huang, Y.Cheng, H.Chen, X. Mao, R. Gong “Based on graphene tunable dual-band terahertz metamaterial absorber with wide-angle” ,Optics Communications, Vol 415, 194-201 (2018) Fig 13a. schematic of MMA Fig 13b. unit cell of absorber Fig 13c. absorbance of the MMA with (a) non-SGP and SGP; (b) lossfree and loss dielectric
- 41. Ultra-thin and broadbandtunable metamaterial graphene absorber Xiong, Han; Wu, Ying-Bo; Dong, Ji; Tang, Ming-Chun; Jiang, Yan-Nan; Zeng, Xiao-Ping (2018). Ultra-thin and broadband tunable metamaterial graphene absorber. Optics Express, 26(2) Fig 14b. Reflection spectra with different Fermi level Fig 14a. schematic diagram and geometric parameters of the proposed MGA unit cell
- 42. Indium Antimoninde (InSb) •Semiconductor material from III-V group • Band gap 1.44ev • Thermally tuning medium as its electromagnetic properties are very sensitive to temperature. • The complexed value of permittivity of InSb is temperature dependent given by Drude model [48-49]; 𝜀 𝑤 = ε∞− ω2 p/(ω2+iωϒ) where, ε∞ =high freq. permittivity ϒ= damping constant ω= angular frequency ωp= plasma frequency
- 43. Strontium Titanate (STO) •Incipient ferroelectric materials • Dielectric material having unique properties including high dielectric constant, low dielectric loss, superior insulation, and good chemical stability . • The most attractive property is that the high dielectric constant of the STO can be adjusted dynamically by varying external environment temperature or by changing the applied electric field. • The permittivity of STO can be calculated by [50]; 𝜀 𝑤 = ε∞− F/(𝑘0 2 - 𝑘2 −i 𝑘ϒ) where, ε∞ =high freq. permittivity=9.6 F(cm-2)= 2.3*106 ko (cm-1) = soft mode wave no ϒ(cm-1)= damping constant The relationship between soft mode wave number k0 and damping constant γ with the external temperature can be expressed as follows: ϒ 𝑇 = −3.3 + 0.094𝑇 𝑘0 𝑇 = 31.2(𝑇 − 42.5)
- 44. Temperature dependent permittivityof STO Real and imaginary value of relative permittivity has been obtained using MATLAB software [51] Fig 15a. real part of permittivity of STO with different temperatures and frequencies Fig 15b. imaginary part of permittivity of STO with different temperatures and frequencies
- 45. Germanium Antimont Telluride(Ge-Sb-Te) • Phase change material • Two states: amorphous and crystalline with different electromagnetic characteristics • The crystallization temp. of GST is 1600c and melting temp. is 6000c. • GST-based systems provide nearly perfect absorption in the IR and visible light regimes • Refractive index of GSTs is wavelength-dependent and Dielectric constant of GST is given by [52-53]: 𝜀𝑥 − 1 𝜀𝑥 + 2 = 𝑥 𝜀𝑐 − 1 𝜀𝑐 + 2 + 1 − 𝑥 𝜀𝑎 − 1 𝜀𝑎 + 2 where εc = 6.3 & εa = 4.3 are dielectric constant of crystalline (x=1) and amorphous (x=0) states GST alloys are known to have advantages over other phase changing material having relatively lower dissipative loss in near infra red regime and nonvolatility i.e. preserving the amorphous/crystalline state even in the absence of the input power • Tunable metamaterials can be realized by the material crystalline phase change, which leads to the change of dielectric properties. The crystalline phase transition leads to electrical and optical property changes such as resistivity, color, and refractive indices
- 46. Graphene • Graphene, atwo-dimensional version of graphite, consists of a planar atomic layer of carbon atoms bonded in a hexagonal structure. • Thinnest material having unique property such as optical transparency, flexibility, high electron mobility . • Graphene sheet can be managed to have a great conductivity amount due to its high electron mobility. The electron mobility of this platform can be adjusted either by chemical doping or gate voltage to produce desired conductivity in the frequency region of interest Fig 17. hexagonal lattice of graphene • Permittivity of graphene given as: [54-55] 𝜀𝑔= 1+i 𝑁𝜎 𝑤𝜀0𝑡𝑔 Where, N =the number of graphene layers tg= thickness of the graphene plate ɛ0= permittivity of vacuum σ = conductivity of graphene
- 47. Problem Identification • Dynamiccontrol of EM resonant response for the real time manipulation in THz radiation • Dynamic control of THz devices
- 48. Approaches to befollowed • Hybridization of two or more techniques. • Use of tunable dielectrics
- 49. Some of thepaper implemented in CST Equivalent circuit model of an ultra-thin polarization independent triple band metamaterial absorber Bhattacharyya, S., Ghosh, S. and Srivastava, K.V., Equivalent circuit model of an ultra-thin polarization-independent triple band metamaterial absorber. AIP Advances, 4(9), p.097127 (2014). a= 10mm w=0.2mm r1=4.625 r2=3.075mm r3= 2.15mm fig 18. top view of unit cell of the proposed absorber
- 50. Fig 19. comparisonof simulated result with that of proposed results
- 51. Graphene pixel-based polarization-insensitivemetasurface for almost perfect and wideband terahertz absorption Pankaj kumar,Akhlesh lakhtakia,& Pradip k. Jain Graphene pixel-based polarization- insensitive metasurface for almost perfect and wideband terahertz absorption Vol. 36, No. 8 / August 2019 / Journal of the Optical Society of America a=9.6µm b=3µm d=0.2µm Lsub=9.6µm Fig 20. top view of meta atoms
- 52. Fig 21. comparisonof simulated result with that of proposed results
- 53. Sambit Kumar Ghosh,Vinit Singh Yadav, Santanu Das, & Somak Bhattacharyya Tunable Graphene-Based Metasurface for Polarization-Independent Broadband Absorption in Lower Mid-Infrared (MIR) Range IEEE Transactions on Electromagnetic Compatibility 1-9 , Tunable Graphene-Based Metasurface for Polarization-Independent Broadband Absorption in Lower Mid-Infrared (MIR) Range a=6µm q=1µm d=1µm n=1µm c=1.75µm b=2.5 m=0.125 e=0.25µ Fig 22a. top view of unit cell Fig 22b. front view of unit cell
- 54. Fig 23. comparisonof simulated result with that of proposed results
- 55. Future work • Studyof other tunable materials • Incorporation of materials in devices
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