Broadband Terahertz Polarizing Beam Splitter Based on a Graphene-Based Defective One-Dimensional Photonic Crystal
Seeking operative terahertz (THz) devices has always stimulated considerable attention. Of particular interest is the THz beam splitter. Here, a tunable THz polarizing beam splitter (PBS) is proposed based on a graphene-embedded quarter-wave stack with a central defect layer of air. The spectral per...
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2019-01-01
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| author | Ziba Saleki Yurui Fang Samad Roshan Entezar |
| author_facet | Ziba Saleki Yurui Fang Samad Roshan Entezar |
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| description | Seeking operative terahertz (THz) devices has always stimulated considerable attention. Of particular interest is the THz beam splitter. Here, a tunable THz polarizing beam splitter (PBS) is proposed based on a graphene-embedded quarter-wave stack with a central defect layer of air. The spectral performance of the structure is investigated by the transfer matrix method. It is found that the electromagnetic waves can be decomposed into two separate polarized waves at incident angles greater than the critical angle. Furthermore, it is shown that a new kind of Brewster angle is found at the low THz frequencies due to the existence of the graphene nano-layers. The appearance of this angle which we call it the graphene induced Brewster angle results in the separation of TM- and TE- polarized waves at the low THz frequencies (<inline-formula><tex-math notation="LaTeX">$f< 2$</tex-math></inline-formula> THz) in addition to the high THz region. It is shown that the working frequency range of PBS can be easily tuned by adjusting the width of the defect layer of air and also by tuning the chemical potential of graphene nano-layers via a gate voltage. The analysis of the proposed PBS is confirmed by the Finite Element Method (FEM) simulations that were performed with the commercial software COMSOL 5.2. Our investigations also reveal that the high transmission extinction ratio (<inline-formula><tex-math notation="LaTeX">$>200$</tex-math></inline-formula> dB) for TM waves with frequency <inline-formula><tex-math notation="LaTeX">$f< 2$</tex-math></inline-formula> THz is achieved by increasing the chemical potential to 0.5 eV. Moreover, this structure can exhibit extremely high extinction ratio for TE waves with high THz frequencies. Finally, the degree of polarization equals to one is reported for the PBS proposed here. This structure offers the opportunity to realize a high-efficiency PBS with very high extinction ratios at the broadband THz frequency. |
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| language | English |
| publishDate | 2019-01-01 |
| publisher | IEEE |
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| series | IEEE Photonics Journal |
| spelling | doaj-art-99d97792d8d14cec86b929a22fc830d62025-08-20T02:42:01ZengIEEEIEEE Photonics Journal1943-06552019-01-0111511310.1109/JPHOT.2019.29350848805387Broadband Terahertz Polarizing Beam Splitter Based on a Graphene-Based Defective One-Dimensional Photonic CrystalZiba Saleki0https://orcid.org/0000-0002-7562-8893Yurui Fang1https://orcid.org/0000-0002-3098-7681Samad Roshan Entezar2https://orcid.org/0000-0003-1699-9114Key Laboratory of Materials Modification by Laser, Electron, and Ion Beams (Ministry of Education), School of Physics, Dalian University of Technology, Dalian, ChinaKey Laboratory of Materials Modification by Laser, Electron, and Ion Beams (Ministry of Education), School of Physics, Dalian University of Technology, Dalian, ChinaFaculty of Physics, University of Tabriz, Tabriz, IranSeeking operative terahertz (THz) devices has always stimulated considerable attention. Of particular interest is the THz beam splitter. Here, a tunable THz polarizing beam splitter (PBS) is proposed based on a graphene-embedded quarter-wave stack with a central defect layer of air. The spectral performance of the structure is investigated by the transfer matrix method. It is found that the electromagnetic waves can be decomposed into two separate polarized waves at incident angles greater than the critical angle. Furthermore, it is shown that a new kind of Brewster angle is found at the low THz frequencies due to the existence of the graphene nano-layers. The appearance of this angle which we call it the graphene induced Brewster angle results in the separation of TM- and TE- polarized waves at the low THz frequencies (<inline-formula><tex-math notation="LaTeX">$f< 2$</tex-math></inline-formula> THz) in addition to the high THz region. It is shown that the working frequency range of PBS can be easily tuned by adjusting the width of the defect layer of air and also by tuning the chemical potential of graphene nano-layers via a gate voltage. The analysis of the proposed PBS is confirmed by the Finite Element Method (FEM) simulations that were performed with the commercial software COMSOL 5.2. Our investigations also reveal that the high transmission extinction ratio (<inline-formula><tex-math notation="LaTeX">$>200$</tex-math></inline-formula> dB) for TM waves with frequency <inline-formula><tex-math notation="LaTeX">$f< 2$</tex-math></inline-formula> THz is achieved by increasing the chemical potential to 0.5 eV. Moreover, this structure can exhibit extremely high extinction ratio for TE waves with high THz frequencies. Finally, the degree of polarization equals to one is reported for the PBS proposed here. This structure offers the opportunity to realize a high-efficiency PBS with very high extinction ratios at the broadband THz frequency.https://ieeexplore.ieee.org/document/8805387/Polarizing beam-splitterdefective photonic crystalgraphene nano-layersextinction ratiodegree of polarization |
| spellingShingle | Ziba Saleki Yurui Fang Samad Roshan Entezar Broadband Terahertz Polarizing Beam Splitter Based on a Graphene-Based Defective One-Dimensional Photonic Crystal IEEE Photonics Journal Polarizing beam-splitter defective photonic crystal graphene nano-layers extinction ratio degree of polarization |
| title | Broadband Terahertz Polarizing Beam Splitter Based on a Graphene-Based Defective One-Dimensional Photonic Crystal |
| title_full | Broadband Terahertz Polarizing Beam Splitter Based on a Graphene-Based Defective One-Dimensional Photonic Crystal |
| title_fullStr | Broadband Terahertz Polarizing Beam Splitter Based on a Graphene-Based Defective One-Dimensional Photonic Crystal |
| title_full_unstemmed | Broadband Terahertz Polarizing Beam Splitter Based on a Graphene-Based Defective One-Dimensional Photonic Crystal |
| title_short | Broadband Terahertz Polarizing Beam Splitter Based on a Graphene-Based Defective One-Dimensional Photonic Crystal |
| title_sort | broadband terahertz polarizing beam splitter based on a graphene based defective one dimensional photonic crystal |
| topic | Polarizing beam-splitter defective photonic crystal graphene nano-layers extinction ratio degree of polarization |
| url | https://ieeexplore.ieee.org/document/8805387/ |
| work_keys_str_mv | AT zibasaleki broadbandterahertzpolarizingbeamsplitterbasedonagraphenebaseddefectiveonedimensionalphotoniccrystal AT yuruifang broadbandterahertzpolarizingbeamsplitterbasedonagraphenebaseddefectiveonedimensionalphotoniccrystal AT samadroshanentezar broadbandterahertzpolarizingbeamsplitterbasedonagraphenebaseddefectiveonedimensionalphotoniccrystal |