Parameter Investigations of Waveguide-Integrated Lithium Niobate Photonic Crystal Microcavity
Despite significant progress, fabricating two-dimensional (2D) lithium niobate (LN)-based photonic crystal (PhC) cavities integrated with tapered and PhC waveguides remains challenging, due to structural imperfections. Notable, especially, are variations in hole radius (<i>r</i>) and inc...
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2025-05-01
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| author | Sohail Muhammad Dingwei Chen Chengwei Xian Jun Zhou Zhongke Lei Pengju Kuang Liang Ma Guangjun Wen Boyu Fan Yongjun Huang |
| author_facet | Sohail Muhammad Dingwei Chen Chengwei Xian Jun Zhou Zhongke Lei Pengju Kuang Liang Ma Guangjun Wen Boyu Fan Yongjun Huang |
| author_sort | Sohail Muhammad |
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| description | Despite significant progress, fabricating two-dimensional (2D) lithium niobate (LN)-based photonic crystal (PhC) cavities integrated with tapered and PhC waveguides remains challenging, due to structural imperfections. Notable, especially, are variations in hole radius (<i>r</i>) and inclination angle (°), which induce bandgap shifts and degrade quality factors (Q-factor). These fabrication errors underscore the critical need to address nanoscale tolerances. Here, we systematically investigate the impacts of key geometric parameters on optical performance and optimize a 2D LN-based cavity integrated with taper and PhC waveguide system. Using a 3D Finite-Difference Time-Domain (FDTD) and varFDTD simulations, we identify stringent fabrication thresholds. The <i>a</i> must exceed 0.72 µm to sustain Q > <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><msup><mrow><mn>10</mn></mrow><mrow><mn>7</mn></mrow></msup></mrow></semantics></math></inline-formula>; reducing <i>a</i> to 0.69 µm collapses Q-factors below <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><msup><mrow><mn>10</mn></mrow><mrow><mn>4</mn></mrow></msup></mrow></semantics></math></inline-formula>, due to under-coupled modes and bandgap misalignment, which necessitates ±0.005 µm precision. When an <i>r</i> < 0.22 µm weakens confinement, Q plummets to 2 × <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><msup><mrow><mn>10</mn></mrow><mrow><mn>4</mn></mrow></msup></mrow></semantics></math></inline-formula> at <i>r</i> = 0.20 µm (±0.01 µm etching tolerance). Inclination angles < 70° induce 100× Q-factor losses, requiring ±2° alignment for symmetric modes. Air slot width (<i>s</i>) variations shift resonant wavelengths and require optimization in coordination with the inclination angle. By optimizing <i>s</i> and the inclination angle (at 70°), we achieve a record Q-factor of 6.21 ×<inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mo> </mo><msup><mrow><mn>10</mn></mrow><mrow><mn>6</mn></mrow></msup></mrow></semantics></math></inline-formula>, with, in addition, C-band compatibility (1502–1581 nm). This work establishes rigorous design–fabrication guidelines, demonstrating the potential for LN-based photonic devices with high nano-fabrication robustness. |
| format | Article |
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| spelling | doaj-art-cb64b532634649db8a7f68945cc8178b2025-08-20T01:56:41ZengMDPI AGPhotonics2304-67322025-05-0112547510.3390/photonics12050475Parameter Investigations of Waveguide-Integrated Lithium Niobate Photonic Crystal MicrocavitySohail Muhammad0Dingwei Chen1Chengwei Xian2Jun Zhou3Zhongke Lei4Pengju Kuang5Liang Ma6Guangjun Wen7Boyu Fan8Yongjun Huang9School of Information and Communication Engineering, Sichuan Provincial Engineering Research Center of Communication Technology for Intelligent IoT, University of Electronic Science and Technology of China, Chengdu 611731, ChinaSchool of Information and Communication Engineering, Sichuan Provincial Engineering Research Center of Communication Technology for Intelligent IoT, University of Electronic Science and Technology of China, Chengdu 611731, ChinaSchool of Information and Communication Engineering, Sichuan Provincial Engineering Research Center of Communication Technology for Intelligent IoT, University of Electronic Science and Technology of China, Chengdu 611731, ChinaSichuan Guoruan Technology Group Co., Ltd., Chengdu 610031, ChinaSichuan Guoruan Technology Group Co., Ltd., Chengdu 610031, ChinaSchool of Information and Communication Engineering, Sichuan Provincial Engineering Research Center of Communication Technology for Intelligent IoT, University of Electronic Science and Technology of China, Chengdu 611731, ChinaSchool of Information and Communication Engineering, Sichuan Provincial Engineering Research Center of Communication Technology for Intelligent IoT, University of Electronic Science and Technology of China, Chengdu 611731, ChinaSchool of Information and Communication Engineering, Sichuan Provincial Engineering Research Center of Communication Technology for Intelligent IoT, University of Electronic Science and Technology of China, Chengdu 611731, ChinaSchool of Information and Communication Engineering, Sichuan Provincial Engineering Research Center of Communication Technology for Intelligent IoT, University of Electronic Science and Technology of China, Chengdu 611731, ChinaSchool of Information and Communication Engineering, Sichuan Provincial Engineering Research Center of Communication Technology for Intelligent IoT, University of Electronic Science and Technology of China, Chengdu 611731, ChinaDespite significant progress, fabricating two-dimensional (2D) lithium niobate (LN)-based photonic crystal (PhC) cavities integrated with tapered and PhC waveguides remains challenging, due to structural imperfections. Notable, especially, are variations in hole radius (<i>r</i>) and inclination angle (°), which induce bandgap shifts and degrade quality factors (Q-factor). These fabrication errors underscore the critical need to address nanoscale tolerances. Here, we systematically investigate the impacts of key geometric parameters on optical performance and optimize a 2D LN-based cavity integrated with taper and PhC waveguide system. Using a 3D Finite-Difference Time-Domain (FDTD) and varFDTD simulations, we identify stringent fabrication thresholds. The <i>a</i> must exceed 0.72 µm to sustain Q > <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><msup><mrow><mn>10</mn></mrow><mrow><mn>7</mn></mrow></msup></mrow></semantics></math></inline-formula>; reducing <i>a</i> to 0.69 µm collapses Q-factors below <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><msup><mrow><mn>10</mn></mrow><mrow><mn>4</mn></mrow></msup></mrow></semantics></math></inline-formula>, due to under-coupled modes and bandgap misalignment, which necessitates ±0.005 µm precision. When an <i>r</i> < 0.22 µm weakens confinement, Q plummets to 2 × <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><msup><mrow><mn>10</mn></mrow><mrow><mn>4</mn></mrow></msup></mrow></semantics></math></inline-formula> at <i>r</i> = 0.20 µm (±0.01 µm etching tolerance). Inclination angles < 70° induce 100× Q-factor losses, requiring ±2° alignment for symmetric modes. Air slot width (<i>s</i>) variations shift resonant wavelengths and require optimization in coordination with the inclination angle. By optimizing <i>s</i> and the inclination angle (at 70°), we achieve a record Q-factor of 6.21 ×<inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mo> </mo><msup><mrow><mn>10</mn></mrow><mrow><mn>6</mn></mrow></msup></mrow></semantics></math></inline-formula>, with, in addition, C-band compatibility (1502–1581 nm). This work establishes rigorous design–fabrication guidelines, demonstrating the potential for LN-based photonic devices with high nano-fabrication robustness.https://www.mdpi.com/2304-6732/12/5/4752D LN-based PhC optical cavityPhC waveguidetaper waveguideparametric investigation |
| spellingShingle | Sohail Muhammad Dingwei Chen Chengwei Xian Jun Zhou Zhongke Lei Pengju Kuang Liang Ma Guangjun Wen Boyu Fan Yongjun Huang Parameter Investigations of Waveguide-Integrated Lithium Niobate Photonic Crystal Microcavity Photonics 2D LN-based PhC optical cavity PhC waveguide taper waveguide parametric investigation |
| title | Parameter Investigations of Waveguide-Integrated Lithium Niobate Photonic Crystal Microcavity |
| title_full | Parameter Investigations of Waveguide-Integrated Lithium Niobate Photonic Crystal Microcavity |
| title_fullStr | Parameter Investigations of Waveguide-Integrated Lithium Niobate Photonic Crystal Microcavity |
| title_full_unstemmed | Parameter Investigations of Waveguide-Integrated Lithium Niobate Photonic Crystal Microcavity |
| title_short | Parameter Investigations of Waveguide-Integrated Lithium Niobate Photonic Crystal Microcavity |
| title_sort | parameter investigations of waveguide integrated lithium niobate photonic crystal microcavity |
| topic | 2D LN-based PhC optical cavity PhC waveguide taper waveguide parametric investigation |
| url | https://www.mdpi.com/2304-6732/12/5/475 |
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