Highly Efficient Polarization-Insensitive Grating Couplers on Thin-Film Lithium Niobate with an Integrated Gold Layer
The thin-film lithium niobate platform, which is emerging as a promising photonic integration platform, currently lacks a polarization-insensitive grating coupler (GC), a crucial component for polarization-independent fiber interfaces. This limitation restricts its use in many applications, such as...
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| Format: | Article |
| Language: | English |
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MDPI AG
2025-01-01
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| Series: | Photonics |
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| Online Access: | https://www.mdpi.com/2304-6732/12/2/111 |
| _version_ | 1826581637685575680 |
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| author | Alaa Sultan Mostafa Khalil Leila Mehravar Chang-qing Xu |
| author_facet | Alaa Sultan Mostafa Khalil Leila Mehravar Chang-qing Xu |
| author_sort | Alaa Sultan |
| collection | DOAJ |
| description | The thin-film lithium niobate platform, which is emerging as a promising photonic integration platform, currently lacks a polarization-insensitive grating coupler (GC), a crucial component for polarization-independent fiber interfaces. This limitation restricts its use in many applications, such as polarization-insensitive modulation systems and polarization management. In this study, we propose a polarization-insensitive nonuniform GC, achieved by intersecting optimal TE- and TM-mode grating periods. Based on our simulation results, the proposed design delivers a coupling efficiency (CE) of 80% for TE and 78.5% for TM polarization, with a polarization-dependent loss of less than 0.14 dB at a wavelength of 1550 nm. The inserted gold layer, i.e., that inside the substrate layer, boosts the CEs of the optimal TE- and TM-mode GC by about 50%, resulting in a highly efficient, polarization-insensitive solution. This advancement enables on-chip polarization diversity applications on the thin-film lithium niobate platform. We also investigate the fabrication and alignment tolerances of the proposed design to ensure robust performance under practical conditions. |
| first_indexed | 2025-03-14T14:53:14Z |
| format | Article |
| id | doaj.art-8df98ff58bff4686b262009822ed6945 |
| institution | Directory Open Access Journal |
| issn | 2304-6732 |
| language | English |
| last_indexed | 2025-03-14T14:53:14Z |
| publishDate | 2025-01-01 |
| publisher | MDPI AG |
| record_format | Article |
| series | Photonics |
| spelling | doaj.art-8df98ff58bff4686b262009822ed69452025-02-25T13:43:41ZengMDPI AGPhotonics2304-67322025-01-0112211110.3390/photonics12020111Highly Efficient Polarization-Insensitive Grating Couplers on Thin-Film Lithium Niobate with an Integrated Gold LayerAlaa Sultan0Mostafa Khalil1Leila Mehravar2Chang-qing Xu3Department of Engineering Physics, McMaster University, Hamilton, ON L8S 4L7, CanadaDepartment of Engineering Physics, McMaster University, Hamilton, ON L8S 4L7, CanadaDepartment of Engineering Physics, McMaster University, Hamilton, ON L8S 4L7, CanadaDepartment of Engineering Physics, McMaster University, Hamilton, ON L8S 4L7, CanadaThe thin-film lithium niobate platform, which is emerging as a promising photonic integration platform, currently lacks a polarization-insensitive grating coupler (GC), a crucial component for polarization-independent fiber interfaces. This limitation restricts its use in many applications, such as polarization-insensitive modulation systems and polarization management. In this study, we propose a polarization-insensitive nonuniform GC, achieved by intersecting optimal TE- and TM-mode grating periods. Based on our simulation results, the proposed design delivers a coupling efficiency (CE) of 80% for TE and 78.5% for TM polarization, with a polarization-dependent loss of less than 0.14 dB at a wavelength of 1550 nm. The inserted gold layer, i.e., that inside the substrate layer, boosts the CEs of the optimal TE- and TM-mode GC by about 50%, resulting in a highly efficient, polarization-insensitive solution. This advancement enables on-chip polarization diversity applications on the thin-film lithium niobate platform. We also investigate the fabrication and alignment tolerances of the proposed design to ensure robust performance under practical conditions.https://www.mdpi.com/2304-6732/12/2/111thin-film lithium niobateoptical waveguidegrating couplers |
| spellingShingle | Alaa Sultan Mostafa Khalil Leila Mehravar Chang-qing Xu Highly Efficient Polarization-Insensitive Grating Couplers on Thin-Film Lithium Niobate with an Integrated Gold Layer Photonics thin-film lithium niobate optical waveguide grating couplers |
| title | Highly Efficient Polarization-Insensitive Grating Couplers on Thin-Film Lithium Niobate with an Integrated Gold Layer |
| title_full | Highly Efficient Polarization-Insensitive Grating Couplers on Thin-Film Lithium Niobate with an Integrated Gold Layer |
| title_fullStr | Highly Efficient Polarization-Insensitive Grating Couplers on Thin-Film Lithium Niobate with an Integrated Gold Layer |
| title_full_unstemmed | Highly Efficient Polarization-Insensitive Grating Couplers on Thin-Film Lithium Niobate with an Integrated Gold Layer |
| title_short | Highly Efficient Polarization-Insensitive Grating Couplers on Thin-Film Lithium Niobate with an Integrated Gold Layer |
| title_sort | highly efficient polarization insensitive grating couplers on thin film lithium niobate with an integrated gold layer |
| topic | thin-film lithium niobate optical waveguide grating couplers |
| url | https://www.mdpi.com/2304-6732/12/2/111 |
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