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Backscattering design for a focusing grating coupler with fully etched slots for transverse magnetic modes
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Published in: | Scientific reports volume:8; Vol. 8. 2018, 1; Article-number 17746; insgesamt 8 Seiten; year:2018; pages:17746; number:1; extent:8 |
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Authors and Corporations: | , , , , , , , |
Other Authors: | Schulz, Kai Marvin 1987- [Author] • Pitruzzello, Giampaolo [Author] • Fohrmann, Lena Simone [Author] • Petrov, Alexander 1978- [Author] • Eich, Manfred [Author] |
Type of Resource: | E-Book Component Part |
Language: | English |
published: |
2018
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Series: |
Scientific reports, Vol. 8. 2018, 1; Article-number 17746; insgesamt 8 Seiten
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Source: | Verbunddaten SWB Lizenzfreie Online-Ressourcen |
ISSN: | 2045-2322 |
Summary: | Grating couplers are a fundamental building block of integrated optics as they allow light to be coupled from free-space to on-chip components and vice versa. A challenging task in designing any grating coupler is represented by the need for reducing back reflections at the waveguide-grating interface, which introduce additional losses and undesirable interference fringes. Here, we present a design approach for focusing TM grating couplers that minimizes these unwanted reflections by introducing a modified slot that fulfills an anti-reflection condition. We show that this antireflection condition can be met only for the Bloch mode of the grating that concentrates in the dielectric. As a consequence the light is scattered from the grating coupler with a negative angle, referred to as “backscattering design”. Our analytic model shows that the anti-reflection condition is transferrable to grating couplers on different waveguide platforms and that it applies for both TE and TM polarizations. Our experimentally realized focusing grating coupler for TM-modes on the silicon photonics platform has a coupling loss of (3.95 ± 0.15) dB at a wavelength of 1.55 µm. It has feature sizes above 200 nm and fully etched slots. The reflectivity between the grating coupler and the connected waveguide is suppressed to below 0.16%. |
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Physical Description: |
Illustrationen, Diagramme 8 |
ISSN: | 2045-2322 |
DOI: | 10.1038/s41598-018-36082-z |