High-efficiency broadband grating out-coupler for thick silicon waveguides with a tuned SiGe layer
We design a novel grating out-coupler while maintaining a Gaussian-shaped far-field output. The approach is based on the patterning of a grating in a SiGe layer on the top surface of a 3-μm-thick Si waveguide. The grating aims at coupling the guided signal into a beam vertically out from the surface...
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| Main Authors: | , , , , |
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| Format: | Article |
| Language: | English |
| Published: |
EDP Sciences
2025-01-01
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| Series: | Journal of the European Optical Society-Rapid Publications |
| Subjects: | |
| Online Access: | https://jeos.edpsciences.org/articles/jeos/full_html/2025/02/jeos20250032/jeos20250032.html |
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| Summary: | We design a novel grating out-coupler while maintaining a Gaussian-shaped far-field output. The approach is based on the patterning of a grating in a SiGe layer on the top surface of a 3-μm-thick Si waveguide. The grating aims at coupling the guided signal into a beam vertically out from the surface of the chip, i.e., out-coupling. The use of a high refractive index alloy, i.e., silicon-germanium, allows a tunability of the effective index of the guided mode and to modify the field distribution enabling a higher efficiency of the grating. It yields a theoretical efficiency of 75% at the central wavelength of 1583 nm. The overall length of this grating coupler is 500 μm, and the output light is detected at 1 μm above the grating. This type of long grating coupler is intended to be eventually used as sensor in LiDAR (Light detection and ranging) applications. |
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| ISSN: | 1990-2573 |