High-Performance and Fabrication-Tolerant 3 dB Adiabatic Coupler Based on Ultralow-Loss Silicon Waveguide by Tri-Layer Hard Mask Etching Process

High-Performance and Fabrication-Tolerant 3 dB Adiabatic Coupler Based on Ultralow-Loss Silicon Waveguide by Tri-Layer Hard Mask Etching Process

Silicon photonics has emerged as critical for advancing photonic integrated circuits (PICs), but waveguide losses, primarily resulting from sidewall roughness, remain a primary challenge. In this work, we demonstrate a tri-layer hard mask etching process that produces strip silicon waveguides with p...

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Bibliographic Details
Main Authors: Ke Zhang, Yunchu Yu, Nanfei Zhu, Senlin Zhang, Jie Sun, Shijin Ding, David Wei Zhang
Format: Article
Language:English
Published: MDPI AG 2025-06-01
Series:Nanomaterials
Subjects:
silicon photonics
ultralow loss
waveguide
adiabatic directional coupler
Online Access:https://www.mdpi.com/2079-4991/15/12/947
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Summary:Silicon photonics has emerged as critical for advancing photonic integrated circuits (PICs), but waveguide losses, primarily resulting from sidewall roughness, remain a primary challenge. In this work, we demonstrate a tri-layer hard mask etching process that produces strip silicon waveguides with propagation losses as low as 1.48 dB/cm, i.e., a 37% improvement over the conventional Si<sub>3</sub>N<sub>4</sub> hard mask technique. Based on the abovementioned approach, the fabricated 3 dB adiabatic directional couplers achieve a nearly ideal splitting ratio of 50.2:49.8 as well as an excess loss of 0.067 dB. These results indicate that the tri-layer hard mask etching process enables scalable and ultralow-loss PICs to be fabricated for high-speed optical interconnects and quantum computing systems.
ISSN:2079-4991

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