Research on Envelope Profile of Lithium Niobate on Insulator Stepped-Mode Spot Size Converter
To enhance the end-face coupling efficiency of lithium niobate on insulator (LNOI) chips, in conjunction with current device fabrication processes, a stepped spot size converter (SSC) based on a special outer envelope profile has been proposed and investigated. This stepped SSC can reduce the coupli...
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MDPI AG
2025-01-01
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| Series: | Micromachines |
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| Online Access: | https://www.mdpi.com/2072-666X/16/1/109 |
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| author | Jianfeng Bao Dengcai Yang Zhiyu Chen Jingyuan Zhang Feng Yang |
| author_facet | Jianfeng Bao Dengcai Yang Zhiyu Chen Jingyuan Zhang Feng Yang |
| author_sort | Jianfeng Bao |
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| description | To enhance the end-face coupling efficiency of lithium niobate on insulator (LNOI) chips, in conjunction with current device fabrication processes, a stepped spot size converter (SSC) based on a special outer envelope profile has been proposed and investigated. This stepped SSC can reduce the coupling loss between the LNOI waveguide and a normal single-mode optical fiber. First, the output waveguide of a mode converter was proposed and simulated, in which the mode field had the biggest overlapping integral factor with a single-mode fiber (MDF ≈ 9.8 μm). Then, a stepped LNOI waveguide, the basic structure of the mode converter, with three kinds of outer envelope profile, was proposed and analyzed. Through analysis of the impacts of different envelope profiles on mode spot conversion efficiency, the relationship between envelope profile and propagation efficiency was obtained. Additionally, the rule of LNOI stair height variation tendency and the pattern of mode spot conversion efficiency for the multi-step mode spot converter in LNOI were obtained. Ultimately, a stepped SSC with a COS-shaped envelope curve was adopted. When this stepped SSC is coupled to single-mode fiber with a mode-field diameter of 9.8 μm, the coupling efficiency of the TE mode was 95.35% at the wavelength of 1550 nm. |
| format | Article |
| id | doaj-art-5fcd6d70f5c44baeb52dd650e1f43863 |
| institution | Kabale University |
| issn | 2072-666X |
| language | English |
| publishDate | 2025-01-01 |
| publisher | MDPI AG |
| record_format | Article |
| series | Micromachines |
| spelling | doaj-art-5fcd6d70f5c44baeb52dd650e1f438632025-01-24T13:42:13ZengMDPI AGMicromachines2072-666X2025-01-0116110910.3390/mi16010109Research on Envelope Profile of Lithium Niobate on Insulator Stepped-Mode Spot Size ConverterJianfeng Bao0Dengcai Yang1Zhiyu Chen2Jingyuan Zhang3Feng Yang4School of Physics and Optoelectronic Engineering, Institute of Laser Engineering, Beijing University of Technology, Beijing 100124, ChinaSchool of Physics and Optoelectronic Engineering, Institute of Laser Engineering, Beijing University of Technology, Beijing 100124, ChinaMicrowave Photonics Technology Laboratory, Chengdu 610036, ChinaSchool of Physics and Optoelectronic Engineering, Institute of Laser Engineering, Beijing University of Technology, Beijing 100124, ChinaSchool of Physics and Optoelectronic Engineering, Institute of Laser Engineering, Beijing University of Technology, Beijing 100124, ChinaTo enhance the end-face coupling efficiency of lithium niobate on insulator (LNOI) chips, in conjunction with current device fabrication processes, a stepped spot size converter (SSC) based on a special outer envelope profile has been proposed and investigated. This stepped SSC can reduce the coupling loss between the LNOI waveguide and a normal single-mode optical fiber. First, the output waveguide of a mode converter was proposed and simulated, in which the mode field had the biggest overlapping integral factor with a single-mode fiber (MDF ≈ 9.8 μm). Then, a stepped LNOI waveguide, the basic structure of the mode converter, with three kinds of outer envelope profile, was proposed and analyzed. Through analysis of the impacts of different envelope profiles on mode spot conversion efficiency, the relationship between envelope profile and propagation efficiency was obtained. Additionally, the rule of LNOI stair height variation tendency and the pattern of mode spot conversion efficiency for the multi-step mode spot converter in LNOI were obtained. Ultimately, a stepped SSC with a COS-shaped envelope curve was adopted. When this stepped SSC is coupled to single-mode fiber with a mode-field diameter of 9.8 μm, the coupling efficiency of the TE mode was 95.35% at the wavelength of 1550 nm.https://www.mdpi.com/2072-666X/16/1/109LNOIcouplingSSCsteppedenvelope |
| spellingShingle | Jianfeng Bao Dengcai Yang Zhiyu Chen Jingyuan Zhang Feng Yang Research on Envelope Profile of Lithium Niobate on Insulator Stepped-Mode Spot Size Converter Micromachines LNOI coupling SSC stepped envelope |
| title | Research on Envelope Profile of Lithium Niobate on Insulator Stepped-Mode Spot Size Converter |
| title_full | Research on Envelope Profile of Lithium Niobate on Insulator Stepped-Mode Spot Size Converter |
| title_fullStr | Research on Envelope Profile of Lithium Niobate on Insulator Stepped-Mode Spot Size Converter |
| title_full_unstemmed | Research on Envelope Profile of Lithium Niobate on Insulator Stepped-Mode Spot Size Converter |
| title_short | Research on Envelope Profile of Lithium Niobate on Insulator Stepped-Mode Spot Size Converter |
| title_sort | research on envelope profile of lithium niobate on insulator stepped mode spot size converter |
| topic | LNOI coupling SSC stepped envelope |
| url | https://www.mdpi.com/2072-666X/16/1/109 |
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