| Authors: | A.H. El-Saeed, A. Elshazly, H. Kobbi, R. Magdziak, G. Lepage, C. Marchese, J. Rahimi Vaskasi, S. Bipul, D. Bode, M.E. Filipcic, D. Velenis, M. Chakrabarti, P. De Heyn, P. Verheyen, P. Absil, F. Ferraro, Y. Ban, J. Van Campenhout, W. Bogaerts, Q. Deng | | Title: | Low-Loss Silicon Directional Coupler with Arbitrary Coupling Ratios for Broadband Wavelength Operation Based on Bent Waveguides | | Format: | International Journal | | Publication date: | 7/2024 | | Journal/Conference/Book: | Journal of Lightwave Technologies
| | DOI: | 10.1109/JLT.2024.3407339 | | Citations: | Look up on Google Scholar
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Abstract
We demonstrate a design for a high-performance 2x2 splitter meeting the essential requirements of broadband coupling, support for arbitrary coupling ratio, ultra low-loss, high fabrication tolerance, and a compact footprint. This is achieved based on a rigorous coupled mode theory analysis of the broadband response of the bent directional coupler (DC) and by demonstrating a full coupling model, with measured broadband values of 0.4, 0.5, 0.6, and 0.7. As a benchmark, we demonstrate a 0.5:0.5 splitter that significantly reduces coupling variation from 0.391 in the traditional DC to just 0.051 over an 80 nm wavelength span. This represents a remarkable 7.67 times reduction in coupling variation. Further, newly-invented low-loss bends were used in the proposed design leading to an ultra low-loss design with negligible excess loss (0.003 ± 0.013 dB). The proposed 0.5:0.5 design is tolerant and shows consistently low coupling variation over a full 300 mm wafer showcasing a maximum cross coupling variation of 0.112 over 80 nm wavelength range, at the extreme edge of the wafer. Futhermore, we augmented the wafer mapping with a waveguide width fabrication tolerance study, confirming the tolerance of the device with a mere 0.061 maximum coupling variation with a waveguide width deviation of +-20 nm over 80 nm wavelength range. These specs make the proposed splitter an attractive component for practical
applications with mass production. Related Research Topics
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