Engineering multimodal spectrum of Cayley tree fractal meta-resonator supercells for ultrabroadband terahertz light absorption
Self-similar fractals provide a degree of freedom for varying the resonance frequency due to the multiscale geometric features involved and are an ideal candidate for ultrabroadband absorbing devices – especially in the terahertz (THz) band where there is a lack of natural absorbing materials. Metas...
| Main Authors: | , , , |
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| Format: | Article |
| Language: | English |
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De Gruyter
2020-01-01
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| Series: | Nanophotonics |
| Subjects: | |
| Online Access: | https://doi.org/10.1515/nanoph-2019-0391 |
| _version_ | 1818363104953630720 |
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| author | Zubair Amna Zubair Muhammad Danner Aaron Mehmood Muhammad Qasim |
| author_facet | Zubair Amna Zubair Muhammad Danner Aaron Mehmood Muhammad Qasim |
| author_sort | Zubair Amna |
| collection | DOAJ |
| description | Self-similar fractals provide a degree of freedom for varying the resonance frequency due to the multiscale geometric features involved and are an ideal candidate for ultrabroadband absorbing devices – especially in the terahertz (THz) band where there is a lack of natural absorbing materials. Metasurface-based THz absorbers often suffer from poor broadband performance, whereas strongly absorbing broadband devices are typically complex multilayer structures. Here, we numerically demonstrate an ultrabroadband, ultrathin, polarization-insensitive, wide-angle, single-layer planar metasurface THz absorber by integrating different Cayley tree fractal resonators into one supercell based on the frequency shifting and multiresonance bands of different fractal orders. In terms of physics, we have exploited the self-similar nature of fractal geometry to engineer the multimodal spectrum of this system. With increasing fractal order N, an increasing number of modes can be excited with certain degeneracies where each mode corresponds to plasmon oscillations at different geometric scales inside fractal. As a result, broad, multipeaked spectra with large degeneracy numbers can be achieved with larger N. Finally, by placing fractals of different order N into one supercell, the coupling and superposition of the neighboring resonances exhibit the desired ultrabroadband response. The proposed absorber provides a wide incident wave angle with a full-width half-maximum absorption bandwidth of more than one octave, i.e. 3.88 THz. Greater than 80% absorption is achieved over a frequency range of 3 THz. Owing to its performance, this work is a step forward in realizing perfect blackbody absorbers that can be easily integrated with bolometric sensing technology to make high-efficient THz-sensing devices. |
| first_indexed | 2024-12-13T21:43:11Z |
| format | Article |
| id | doaj.art-6ead4bbd99fa4de6a2043d6cfa481815 |
| institution | Directory Open Access Journal |
| issn | 2192-8614 |
| language | English |
| last_indexed | 2024-12-13T21:43:11Z |
| publishDate | 2020-01-01 |
| publisher | De Gruyter |
| record_format | Article |
| series | Nanophotonics |
| spelling | doaj.art-6ead4bbd99fa4de6a2043d6cfa4818152022-12-21T23:30:30ZengDe GruyterNanophotonics2192-86142020-01-019363364410.1515/nanoph-2019-0391nanoph-2019-0391Engineering multimodal spectrum of Cayley tree fractal meta-resonator supercells for ultrabroadband terahertz light absorptionZubair Amna0Zubair Muhammad1Danner Aaron2Mehmood Muhammad Qasim3NanoTech Lab, Department of Electrical Engineering, Information Technology University (ITU) of the Punjab, Lahore, PakistanNanoTech Lab, Department of Electrical Engineering, Information Technology University (ITU) of the Punjab, 4th Floor, Arfa Software Technology Park, Ferozepur Road, Lahore 54600, PakistanDepartment of Electrical and Computer Engineering, National University of Singapore, 117583 Singapore, SingaporeNanoTech Lab, Department of Electrical Engineering, Information Technology University (ITU) of the Punjab, 4th Floor, Arfa Software Technology Park, Ferozepur Road, Lahore 54600, PakistanSelf-similar fractals provide a degree of freedom for varying the resonance frequency due to the multiscale geometric features involved and are an ideal candidate for ultrabroadband absorbing devices – especially in the terahertz (THz) band where there is a lack of natural absorbing materials. Metasurface-based THz absorbers often suffer from poor broadband performance, whereas strongly absorbing broadband devices are typically complex multilayer structures. Here, we numerically demonstrate an ultrabroadband, ultrathin, polarization-insensitive, wide-angle, single-layer planar metasurface THz absorber by integrating different Cayley tree fractal resonators into one supercell based on the frequency shifting and multiresonance bands of different fractal orders. In terms of physics, we have exploited the self-similar nature of fractal geometry to engineer the multimodal spectrum of this system. With increasing fractal order N, an increasing number of modes can be excited with certain degeneracies where each mode corresponds to plasmon oscillations at different geometric scales inside fractal. As a result, broad, multipeaked spectra with large degeneracy numbers can be achieved with larger N. Finally, by placing fractals of different order N into one supercell, the coupling and superposition of the neighboring resonances exhibit the desired ultrabroadband response. The proposed absorber provides a wide incident wave angle with a full-width half-maximum absorption bandwidth of more than one octave, i.e. 3.88 THz. Greater than 80% absorption is achieved over a frequency range of 3 THz. Owing to its performance, this work is a step forward in realizing perfect blackbody absorbers that can be easily integrated with bolometric sensing technology to make high-efficient THz-sensing devices.https://doi.org/10.1515/nanoph-2019-0391metasurfaceabsorbercayley tree fractalsdegeneracies |
| spellingShingle | Zubair Amna Zubair Muhammad Danner Aaron Mehmood Muhammad Qasim Engineering multimodal spectrum of Cayley tree fractal meta-resonator supercells for ultrabroadband terahertz light absorption Nanophotonics metasurface absorber cayley tree fractals degeneracies |
| title | Engineering multimodal spectrum of Cayley tree fractal meta-resonator supercells for ultrabroadband terahertz light absorption |
| title_full | Engineering multimodal spectrum of Cayley tree fractal meta-resonator supercells for ultrabroadband terahertz light absorption |
| title_fullStr | Engineering multimodal spectrum of Cayley tree fractal meta-resonator supercells for ultrabroadband terahertz light absorption |
| title_full_unstemmed | Engineering multimodal spectrum of Cayley tree fractal meta-resonator supercells for ultrabroadband terahertz light absorption |
| title_short | Engineering multimodal spectrum of Cayley tree fractal meta-resonator supercells for ultrabroadband terahertz light absorption |
| title_sort | engineering multimodal spectrum of cayley tree fractal meta resonator supercells for ultrabroadband terahertz light absorption |
| topic | metasurface absorber cayley tree fractals degeneracies |
| url | https://doi.org/10.1515/nanoph-2019-0391 |
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