Theoretical and numerical studies of dynamically tunable terahertz graphene-based chiral and anisotropic metamaterials
Asgari, Somayyeh (2024-05-31)
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https://rightsstatements.org/vocab/InC/1.0/
https://urn.fi/URN:NBN:fi:oulu-202405133329
Kuvaus
Tiivistelmä
This thesis investigates how theoretical and numerical approaches can be used to design and analyse tunable terahertz graphene-based chiral and anisotropic metamaterials for applications in optoelectronics. Nine variations of metamaterials were designed and analysed to demonstrate the versatility of the technique: single-, dual-, and multi-function metamaterials working as a filter, multiband absorbers, broadband and multiband mirror, switch, inverter, a refractive index sensor, and a biosensor. Metamaterials were designed and optimized numerically in Computer Simulation Technology (CST) Software, while Equivalent circuit models (ECMs), parameter retrieval method, and Kramers–Kronig relations-based MATLAB codes were utilized in theoretical analysis.
The proposed metamaterial designs are dynamically tunable by varying bias voltage and they showed impressive component level performance in the THz frequency range (0.3–5.5 THz). The best designed metamaterials exhibit a maximum linear dichroism (LD) response of 100%, maximum absorption of 100%, with maximum four absorption/reflection bands, a maximum switching extinction ratio of 33.01 dB and a maximum circular dichroism (CD) response of 20%. From a sensing performance point of view, the maximum refractive index sensitivity was 0.96 THz/refractive index unit. With certain designs, the number and location of the absorption and reflection bands can be adjusted by rotating the incident electromagnetic field.
The obtained results demonstrated the significant potential of metamaterials in various research fields, their potential impact on the optoelectronics industry and the possibility of a proper design to make graphene-based THz metastructure fabrication more feasible.
Tässä opinnäytetyössä tutkitaan, kuinka teoreettisia ja numeerisia lähestymistapoja voidaan käyttää virittävien terahertsigrafeenipohjaisten kiraalisten ja anisotrooppisten metamateriaalien suunnittelussa ja analysoinnissa optoelektroniikan sovelluksiin. Metamateriaalien yhdeksän muunnelmaa suunniteltiin ja analysoitiin osoittamaan tekniikan monipuolisuutta: yksi-, kaksi- ja monitoimimetamateriaalit, jotka toimivat suodattimena, monikaistaiset vaimentimet, laajakaista- ja monikaistapeilit, kytkin, invertteri, taitekerroinanturi ja biosensori. Metamateriaalit suunniteltiin ja optimoitiin numeerisesti Computer Simulation Technology (CST) -ohjelmistossa. Teoreettisessa analyysissä hyödynnettiin ekvivalentteja piirimalleja (ECM), parametrien hakumenetelmää ja Kramers–Kronig-relaatioihin perustuvia MATLAB-koodeja.
Ehdotetut metamateriaalimallit ovat dynaamisesti viritettävissä vaihtelemalla esijännitettä ja ne osoittivat vaikuttavaa komponenttitason suorituskykyä THz-taajuusalueella (0,3–5,5 THz). Parhaiten suunniteltujen metamateriaalien lineaarinen dikroismi (LD) maksimivaste on 100 %, maksimiabsorptio 100 %, enintään neljä absorptio/heijastuskaistaa, suurin kytkentäsammutussuhde 33,01 dB ja maksimi pyöreä dikroismi (CD) vaste 20 %. Tunnistuksen suorituskyvyn kannalta suurin taitekerroinherkkyys oli 0,96 THz/taitekerroinyksikkö. Tietyissä malleissa absorptio- ja heijastuskaistojen lukumäärää ja sijaintia voidaan säätää kiertämällä tulevaa sähkömagneettista kenttää.
Saadut tulokset osoittivat metamateriaalien merkittävän potentiaalin eri tutkimusaloilla, niiden mahdollisen vaikutuksen optoelektroniikan teollisuuteen sekä mahdollisuuden oikeanlaiseen suunnitteluun grafeenipohjaisen THz-metarakenteen valmistuksen mahdollistamiseksi.
Original papers
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Asgari, S., & Fabritius, T. (2020). Equivalent circuit model of graphene chiral multi-band metadevice absorber composed of U-shaped resonator array. Optics Express, 28(26), 39850. https://doi.org/10.1364/OE.412107 https://doi.org/10.1364/OE.412107
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Asgari, S., & Fabritius, T. (2023). Terahertz graphene-based multi-functional anisotropic metamaterial and its equivalent circuit model. Scientific Reports, 13(1), 3433. https://doi.org/10.1038/s41598-023-30605-z https://doi.org/10.1038/s41598-023-30605-z
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Asgari, S., & Fabritius, T. (2021). Graphene-based dual-functional chiral metamirror composed of complementary 90° rotated U-shaped resonator arrays and its equivalent circuit model. Scientific Reports, 11(1), 23827. https://doi.org/10.1038/s41598-021-03457-8 https://doi.org/10.1038/s41598-021-03457-8
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Asgari, S., & Fabritius, T. (2022). Graphene-based multiband chiral metamaterial absorbers comprised of square split-ring resonator arrays with different numbers of gaps, and their equivalent circuit model. IEEE Access, 10, 63658–63671. https://doi.org/10.1109/ACCESS.2022.3183272 https://doi.org/10.1109/ACCESS.2022.3183272
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Asgari, S., & Fabritius, T. (2023). Numerical simulation and equivalent circuit model of multi-band terahertz absorber composed of double-sided graphene comb resonator array. IEEE Access, 11, 36052–36063. https://doi.org/10.1109/ACCESS.2023.3265804 https://doi.org/10.1109/ACCESS.2023.3265804
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Asgari, S., Granpayeh, N., & Fabritius, T. (2020). Controllable terahertz cross-shaped three-dimensional graphene intrinsically chiral metastructure and its biosensing application. Optics Communications, 474, 126080. https://doi.org/10.1016/j.optcom.2020.126080 https://doi.org/10.1016/j.optcom.2020.126080
Osajulkaisut
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Asgari, S., & Fabritius, T. (2020). Equivalent circuit model of graphene chiral multi-band metadevice absorber composed of U-shaped resonator array. Optics Express, 28(26), 39850. https://doi.org/10.1364/OE.412107 https://doi.org/10.1364/OE.412107
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Asgari, S., & Fabritius, T. (2023). Terahertz graphene-based multi-functional anisotropic metamaterial and its equivalent circuit model. Scientific Reports, 13(1), 3433. https://doi.org/10.1038/s41598-023-30605-z https://doi.org/10.1038/s41598-023-30605-z
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Asgari, S., & Fabritius, T. (2021). Graphene-based dual-functional chiral metamirror composed of complementary 90° rotated U-shaped resonator arrays and its equivalent circuit model. Scientific Reports, 11(1), 23827. https://doi.org/10.1038/s41598-021-03457-8 https://doi.org/10.1038/s41598-021-03457-8
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Asgari, S., & Fabritius, T. (2022). Graphene-based multiband chiral metamaterial absorbers comprised of square split-ring resonator arrays with different numbers of gaps, and their equivalent circuit model. IEEE Access, 10, 63658–63671. https://doi.org/10.1109/ACCESS.2022.3183272 https://doi.org/10.1109/ACCESS.2022.3183272
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Asgari, S., & Fabritius, T. (2023). Numerical simulation and equivalent circuit model of multi-band terahertz absorber composed of double-sided graphene comb resonator array. IEEE Access, 11, 36052–36063. https://doi.org/10.1109/ACCESS.2023.3265804 https://doi.org/10.1109/ACCESS.2023.3265804
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Asgari, S., Granpayeh, N., & Fabritius, T. (2020). Controllable terahertz cross-shaped three-dimensional graphene intrinsically chiral metastructure and its biosensing application. Optics Communications, 474, 126080. https://doi.org/10.1016/j.optcom.2020.126080 https://doi.org/10.1016/j.optcom.2020.126080
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