Topological Rainbow Trapping with Expanded Bandwidth in Valley Photonic Crystals
We introduce a novel approach to achieve broadband rainbow trapping in a 2D photonic crystal (PC) platform. By exploiting the concept of valley PCs, we engineer a structure that supports robust topological edge states. A carefully designed rotational angle gradient along the edge state path induces...
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MDPI AG
2025-05-01
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| Series: | Photonics |
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| author | Sayed El. Soliman Israa Abood Naglaa Abdel All Chii-Chang Chen |
| author_facet | Sayed El. Soliman Israa Abood Naglaa Abdel All Chii-Chang Chen |
| author_sort | Sayed El. Soliman |
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| description | We introduce a novel approach to achieve broadband rainbow trapping in a 2D photonic crystal (PC) platform. By exploiting the concept of valley PCs, we engineer a structure that supports robust topological edge states. A carefully designed rotational angle gradient along the edge state path induces frequency-dependent light localization, forming a topological rainbow with a significantly expanded bandwidth. This phenomenon of topological rainbow trapping is attributed to the interplay between valley-dependent topological edge states and the engineered rotational angle gradient. To further enhance light localization and broaden the trapping spectrum, we incorporate a graded radius profile in the bottom row of dielectric columns. Through a combination of rotational angle modulation and radius grading, we successfully realize broadband rainbow trapping with enhanced light localization. Our findings reveal a broad trapping bandwidth spanning from <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mn>0.8314</mn><mi>c</mi><mo>/</mo><mi>a</mi></mrow></semantics></math></inline-formula> to <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mn>0.9205</mn><mi>c</mi><mo>/</mo><mi>a</mi></mrow></semantics></math></inline-formula>, showcasing the potential of this approach for applications in optical frequency filtering, sensing, and information processing. |
| format | Article |
| id | doaj-art-257f311d481c453a99ef1d03fdee94b2 |
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| issn | 2304-6732 |
| language | English |
| publishDate | 2025-05-01 |
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| spelling | doaj-art-257f311d481c453a99ef1d03fdee94b22025-08-20T01:56:41ZengMDPI AGPhotonics2304-67322025-05-0112548710.3390/photonics12050487Topological Rainbow Trapping with Expanded Bandwidth in Valley Photonic CrystalsSayed El. Soliman0Israa Abood1Naglaa Abdel All2Chii-Chang Chen3Physics Department, Faculty of Science, Assiut University, Assiut 71516, EgyptCollege of Physics and Optoelectronic Engineering, Shenzhen University, Shenzhen 518060, ChinaDepartment of Physics, College of Science, Imam Mohammad Ibn Saud Islamic University, Riyadh 11432, Saudi ArabiaDepartment of Optics and Photonics, National Central University, Taoyuan City 320, TaiwanWe introduce a novel approach to achieve broadband rainbow trapping in a 2D photonic crystal (PC) platform. By exploiting the concept of valley PCs, we engineer a structure that supports robust topological edge states. A carefully designed rotational angle gradient along the edge state path induces frequency-dependent light localization, forming a topological rainbow with a significantly expanded bandwidth. This phenomenon of topological rainbow trapping is attributed to the interplay between valley-dependent topological edge states and the engineered rotational angle gradient. To further enhance light localization and broaden the trapping spectrum, we incorporate a graded radius profile in the bottom row of dielectric columns. Through a combination of rotational angle modulation and radius grading, we successfully realize broadband rainbow trapping with enhanced light localization. Our findings reveal a broad trapping bandwidth spanning from <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mn>0.8314</mn><mi>c</mi><mo>/</mo><mi>a</mi></mrow></semantics></math></inline-formula> to <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mn>0.9205</mn><mi>c</mi><mo>/</mo><mi>a</mi></mrow></semantics></math></inline-formula>, showcasing the potential of this approach for applications in optical frequency filtering, sensing, and information processing.https://www.mdpi.com/2304-6732/12/5/487photonic crystalstopological statesbroadbandrainbow tapping |
| spellingShingle | Sayed El. Soliman Israa Abood Naglaa Abdel All Chii-Chang Chen Topological Rainbow Trapping with Expanded Bandwidth in Valley Photonic Crystals Photonics photonic crystals topological states broadband rainbow tapping |
| title | Topological Rainbow Trapping with Expanded Bandwidth in Valley Photonic Crystals |
| title_full | Topological Rainbow Trapping with Expanded Bandwidth in Valley Photonic Crystals |
| title_fullStr | Topological Rainbow Trapping with Expanded Bandwidth in Valley Photonic Crystals |
| title_full_unstemmed | Topological Rainbow Trapping with Expanded Bandwidth in Valley Photonic Crystals |
| title_short | Topological Rainbow Trapping with Expanded Bandwidth in Valley Photonic Crystals |
| title_sort | topological rainbow trapping with expanded bandwidth in valley photonic crystals |
| topic | photonic crystals topological states broadband rainbow tapping |
| url | https://www.mdpi.com/2304-6732/12/5/487 |
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