Free-form catenary-inspired meta-couplers for ultra-high or broadband vertical coupling
Metasurface-assisted waveguide couplers, or meta-couplers, innovatively link free-space optics with on-chip devices, offering flexibility for polarization and wavelength (de)multiplexing, mode-selective coupling, and guided mode manipulation. However, conventional meta-couplers still face challenges...
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| Format: | Article |
| Language: | English |
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De Gruyter
2025-01-01
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| Series: | Nanophotonics |
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| Online Access: | https://doi.org/10.1515/nanoph-2024-0566 |
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| author | Chen Tianqu Xu Mingfeng Pu Mingbo Tang Xi Zheng Yuhan Zeng Qingji Xiao Yuting Ha Yingli Guo Yinghui Zhang Fei Chi Nan Luo Xiangang |
| author_facet | Chen Tianqu Xu Mingfeng Pu Mingbo Tang Xi Zheng Yuhan Zeng Qingji Xiao Yuting Ha Yingli Guo Yinghui Zhang Fei Chi Nan Luo Xiangang |
| author_sort | Chen Tianqu |
| collection | DOAJ |
| description | Metasurface-assisted waveguide couplers, or meta-couplers, innovatively link free-space optics with on-chip devices, offering flexibility for polarization and wavelength (de)multiplexing, mode-selective coupling, and guided mode manipulation. However, conventional meta-couplers still face challenges with low coupling efficiency and narrow bandwidth due to critical near-field coupling caused by waveguide constraints and unit-cell–based design approach, which cannot be accurately addressed using traditional design methods. In this paper, quasi-continuous dielectric catenary arrays are first employed to enhance efficiency and bandwidth by addressing adjacent coupling issues of discrete metasurface. Then, diffraction analysis demonstrates that the performance of forward-designed couplers is hindered by spurious diffraction orders and destructive interference. To further enhance performance, an adjoint-based topology optimization algorithm is utilized to customize electric near-field, which can effectively suppress spurious diffraction orders and destructive near-field interference, achieving ultra-high coupling efficiency of 93 % with 16.7 dB extinction ratios at 1,550 nm. Additionally, a broadband meta-coupler exceeds 350 nm bandwidth with 50 % average coupling efficiency across O- to L-bands using multiobjective optimization. These high-performance devices may render them suitable for applications in optical communications, sensing, and nonlinear optics. Moreover, the inverse design method shows potential for improving the performance of various metasurface-integrated on-chip devices. |
| format | Article |
| id | doaj-art-1362d35e7af94ca09ae644b97eacad51 |
| institution | OA Journals |
| issn | 2192-8614 |
| language | English |
| publishDate | 2025-01-01 |
| publisher | De Gruyter |
| record_format | Article |
| series | Nanophotonics |
| spelling | doaj-art-1362d35e7af94ca09ae644b97eacad512025-08-20T02:28:49ZengDe GruyterNanophotonics2192-86142025-01-011481145115510.1515/nanoph-2024-0566Free-form catenary-inspired meta-couplers for ultra-high or broadband vertical couplingChen Tianqu0Xu Mingfeng1Pu Mingbo2Tang Xi3Zheng Yuhan4Zeng Qingji5Xiao Yuting6Ha Yingli7Guo Yinghui8Zhang Fei9Chi Nan10Luo Xiangang11Department of Communication, Science and Engineering, Fudan University, Shanghai200438, ChinaNational Key Laboratory of Optical Field Manipulation Science and Technology, Chinese Academy of Sciences, Chengdu610209, ChinaNational Key Laboratory of Optical Field Manipulation Science and Technology, Chinese Academy of Sciences, Chengdu610209, ChinaNational Key Laboratory of Optical Field Manipulation Science and Technology, Chinese Academy of Sciences, Chengdu610209, ChinaNational Key Laboratory of Optical Field Manipulation Science and Technology, Chinese Academy of Sciences, Chengdu610209, ChinaNational Key Laboratory of Optical Field Manipulation Science and Technology, Chinese Academy of Sciences, Chengdu610209, ChinaNational Key Laboratory of Optical Field Manipulation Science and Technology, Chinese Academy of Sciences, Chengdu610209, ChinaNational Key Laboratory of Optical Field Manipulation Science and Technology, Chinese Academy of Sciences, Chengdu610209, ChinaNational Key Laboratory of Optical Field Manipulation Science and Technology, Chinese Academy of Sciences, Chengdu610209, ChinaNational Key Laboratory of Optical Field Manipulation Science and Technology, Chinese Academy of Sciences, Chengdu610209, ChinaDepartment of Communication, Science and Engineering, Fudan University, Shanghai200438, ChinaNational Key Laboratory of Optical Field Manipulation Science and Technology, Chinese Academy of Sciences, Chengdu610209, ChinaMetasurface-assisted waveguide couplers, or meta-couplers, innovatively link free-space optics with on-chip devices, offering flexibility for polarization and wavelength (de)multiplexing, mode-selective coupling, and guided mode manipulation. However, conventional meta-couplers still face challenges with low coupling efficiency and narrow bandwidth due to critical near-field coupling caused by waveguide constraints and unit-cell–based design approach, which cannot be accurately addressed using traditional design methods. In this paper, quasi-continuous dielectric catenary arrays are first employed to enhance efficiency and bandwidth by addressing adjacent coupling issues of discrete metasurface. Then, diffraction analysis demonstrates that the performance of forward-designed couplers is hindered by spurious diffraction orders and destructive interference. To further enhance performance, an adjoint-based topology optimization algorithm is utilized to customize electric near-field, which can effectively suppress spurious diffraction orders and destructive near-field interference, achieving ultra-high coupling efficiency of 93 % with 16.7 dB extinction ratios at 1,550 nm. Additionally, a broadband meta-coupler exceeds 350 nm bandwidth with 50 % average coupling efficiency across O- to L-bands using multiobjective optimization. These high-performance devices may render them suitable for applications in optical communications, sensing, and nonlinear optics. Moreover, the inverse design method shows potential for improving the performance of various metasurface-integrated on-chip devices.https://doi.org/10.1515/nanoph-2024-0566integrated photonicstopology optimizationcatenarynanophotonics |
| spellingShingle | Chen Tianqu Xu Mingfeng Pu Mingbo Tang Xi Zheng Yuhan Zeng Qingji Xiao Yuting Ha Yingli Guo Yinghui Zhang Fei Chi Nan Luo Xiangang Free-form catenary-inspired meta-couplers for ultra-high or broadband vertical coupling Nanophotonics integrated photonics topology optimization catenary nanophotonics |
| title | Free-form catenary-inspired meta-couplers for ultra-high or broadband vertical coupling |
| title_full | Free-form catenary-inspired meta-couplers for ultra-high or broadband vertical coupling |
| title_fullStr | Free-form catenary-inspired meta-couplers for ultra-high or broadband vertical coupling |
| title_full_unstemmed | Free-form catenary-inspired meta-couplers for ultra-high or broadband vertical coupling |
| title_short | Free-form catenary-inspired meta-couplers for ultra-high or broadband vertical coupling |
| title_sort | free form catenary inspired meta couplers for ultra high or broadband vertical coupling |
| topic | integrated photonics topology optimization catenary nanophotonics |
| url | https://doi.org/10.1515/nanoph-2024-0566 |
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