Polarization Coupling of <inline-formula><tex-math notation="LaTeX">$X$</tex-math></inline-formula>-Cut Thin Film Lithium Niobate Based Waveguides
Thin film lithium niobate (LN) shows great potentials for highly compact passive and active devices. As LN is an anisotropic material, waveguides made on it exhibit different mode properties from those on conventional isotropic materials. We study the effective refractive indices of fundamental mode...
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IEEE
2020-01-01
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| Series: | IEEE Photonics Journal |
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| Online Access: | https://ieeexplore.ieee.org/document/9095209/ |
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| author | Jingyi Wang Pengxin Chen Daoxin Dai Liu Liu |
| author_facet | Jingyi Wang Pengxin Chen Daoxin Dai Liu Liu |
| author_sort | Jingyi Wang |
| collection | DOAJ |
| description | Thin film lithium niobate (LN) shows great potentials for highly compact passive and active devices. As LN is an anisotropic material, waveguides made on it exhibit different mode properties from those on conventional isotropic materials. We study the effective refractive indices of fundamental modes of two polarizations in etched ridge waveguides on an <inline-formula><tex-math notation="LaTeX">$X$</tex-math></inline-formula>-cut LN thin film. Mode hybridization phenomenon, where the effective refractive indices of the two polarizations are close, is analyzed in detail with different structural parameters. Transmission through a 90° bend, which is a typical routing element for a photonic chip, is simulated. Significant polarization coupling related to the mode evaluation through the bend is observed, and becomes the dominant fact limiting the performance of this element. In order to ensure a low bending loss, the required bending radius is much larger than that for waveguides on an in-plane isotropic material, e.g. a <inline-formula><tex-math notation="LaTeX">$Z$</tex-math></inline-formula>-cut LN thin film. Mode hybridization also plays an important role in the performance of the 90° bend, which should be avoided. Generally, decreasing the thickness of the LN thin film, working at a longer wavelength, or confining the propagation angle on a chip would help to decrease the polarization coupling. |
| format | Article |
| id | doaj-art-127db859b302464bb7e2b861237f18d0 |
| institution | Matheson Library |
| issn | 1943-0655 |
| language | English |
| publishDate | 2020-01-01 |
| publisher | IEEE |
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| series | IEEE Photonics Journal |
| spelling | doaj-art-127db859b302464bb7e2b861237f18d02025-07-01T23:50:27ZengIEEEIEEE Photonics Journal1943-06552020-01-0112311010.1109/JPHOT.2020.29953179095209Polarization Coupling of <inline-formula><tex-math notation="LaTeX">$X$</tex-math></inline-formula>-Cut Thin Film Lithium Niobate Based WaveguidesJingyi Wang0https://orcid.org/0000-0002-9464-2404Pengxin Chen1https://orcid.org/0000-0003-0589-9601Daoxin Dai2https://orcid.org/0000-0002-2769-3009Liu Liu3https://orcid.org/0000-0002-4927-9562South China Academy of Advanced Optoelectronics, Centre for Optical and Electromagnetic Research, Guangdong Provincial Key Laboratory of Optical Information Materials and Technology, South China Normal University, Higher-Education Mega-Center, Guangzhou, ChinaSouth China Academy of Advanced Optoelectronics, Centre for Optical and Electromagnetic Research, Guangdong Provincial Key Laboratory of Optical Information Materials and Technology, South China Normal University, Higher-Education Mega-Center, Guangzhou, ChinaZhejiang Provincial Key Laboratory for Sensing Technologies, State Key Laboratory for Modern Optical Instrumentation, Centre for Optical and Electromagnetic Research, Zhejiang University, Hangzhou, ChinaZhejiang Provincial Key Laboratory for Sensing Technologies, State Key Laboratory for Modern Optical Instrumentation, Centre for Optical and Electromagnetic Research, Zhejiang University, Hangzhou, ChinaThin film lithium niobate (LN) shows great potentials for highly compact passive and active devices. As LN is an anisotropic material, waveguides made on it exhibit different mode properties from those on conventional isotropic materials. We study the effective refractive indices of fundamental modes of two polarizations in etched ridge waveguides on an <inline-formula><tex-math notation="LaTeX">$X$</tex-math></inline-formula>-cut LN thin film. Mode hybridization phenomenon, where the effective refractive indices of the two polarizations are close, is analyzed in detail with different structural parameters. Transmission through a 90° bend, which is a typical routing element for a photonic chip, is simulated. Significant polarization coupling related to the mode evaluation through the bend is observed, and becomes the dominant fact limiting the performance of this element. In order to ensure a low bending loss, the required bending radius is much larger than that for waveguides on an in-plane isotropic material, e.g. a <inline-formula><tex-math notation="LaTeX">$Z$</tex-math></inline-formula>-cut LN thin film. Mode hybridization also plays an important role in the performance of the 90° bend, which should be avoided. Generally, decreasing the thickness of the LN thin film, working at a longer wavelength, or confining the propagation angle on a chip would help to decrease the polarization coupling.https://ieeexplore.ieee.org/document/9095209/Ridge waveguidelithium niobatepolarization coupling |
| spellingShingle | Jingyi Wang Pengxin Chen Daoxin Dai Liu Liu Polarization Coupling of <inline-formula><tex-math notation="LaTeX">$X$</tex-math></inline-formula>-Cut Thin Film Lithium Niobate Based Waveguides IEEE Photonics Journal Ridge waveguide lithium niobate polarization coupling |
| title | Polarization Coupling of <inline-formula><tex-math notation="LaTeX">$X$</tex-math></inline-formula>-Cut Thin Film Lithium Niobate Based Waveguides |
| title_full | Polarization Coupling of <inline-formula><tex-math notation="LaTeX">$X$</tex-math></inline-formula>-Cut Thin Film Lithium Niobate Based Waveguides |
| title_fullStr | Polarization Coupling of <inline-formula><tex-math notation="LaTeX">$X$</tex-math></inline-formula>-Cut Thin Film Lithium Niobate Based Waveguides |
| title_full_unstemmed | Polarization Coupling of <inline-formula><tex-math notation="LaTeX">$X$</tex-math></inline-formula>-Cut Thin Film Lithium Niobate Based Waveguides |
| title_short | Polarization Coupling of <inline-formula><tex-math notation="LaTeX">$X$</tex-math></inline-formula>-Cut Thin Film Lithium Niobate Based Waveguides |
| title_sort | polarization coupling of inline formula tex math notation latex x tex math inline formula cut thin film lithium niobate based waveguides |
| topic | Ridge waveguide lithium niobate polarization coupling |
| url | https://ieeexplore.ieee.org/document/9095209/ |
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