Origins and mitigation of scattering-related propagation losses in suspended GaAs waveguides for quantum photonic integrated circuits

Ljubotina, Miloš (author), Albrechtsen, Marcus (author), Liu, Zhe (author), Midolo, Leonardo (author), Debevc, Andraž (author), Topič, Marko (author), Krč, Janez (author)

Quantum photonic integrated circuits (QPICs) offer a promising path toward scalable quantum technologies. QPICs rely on the integration of many quantum photonic components and interconnecting optical waveguides for generation, manipulation, and detection of single photons. A key challenge in QPICs is the management and minimization of optical losses, which is particularly critical for single-photon applications. In this paper, we investigate optical propagation losses in strip waveguides within suspended gallium arsenide (GaAs) platforms, which can directly host deterministic single-photon sources but suffer high scatteringrelated losses. We systematically analyze different scattering loss contributions by investigating four key waveguide perturbation types: sidewall roughness, top surface roughness, surface particles, and suspension tethers. Our approach combines rigorous 3D finitedifference time-domain (FDTD) simulations with experimental measurements to decouple and quantify individual contributions to the total propagation loss.We study two suspended GaAs platforms operating at different wavelengths: an established 930 nm platform and an emerging 1300 nm platform in the telecommunication O-band. Based on our findings, we identify the dominant scattering loss mechanisms and propose novel design-time guidelines and concrete strategies to reduce the main loss contributions by factors of 2.5–5. These improvements are crucial for enabling complex QPICs directly within the native platform of the single-photon source, supporting advances in integrated quantum technologies.

• Language: English
• Keywords: Optical propagation losses, optical scattering, quantum photonic integrated circuits (QPICs), suspended gallium arsenide (GaAs) strip waveguides, waveguide sidewall roughness, waveguide surface roughness, waveguide surface particles, waveguide suspension tethers
• Work type: Article
• Typology: 1.01 - Original Scientific Article
• Organization: FE - Faculty of Electrical Engineering
• Publication status: Published
• Publication version: Version of Record
• Year: 2025
• Number of pages: 13 str.
• Numbering: Vol. 31, no. 5, art. 6100413
• PID: 20.500.12556/RUL-173333
• UDC: 621.38
• ISSN on article: 1558-4542
• DOI: 10.1109/JSTQE.2025.3576388
• COBISS.SI-ID: 249046531
• Publication date in RUL: 16.09.2025

Record is a part of a journal

• Title: IEEE journal of selected topics in quantum electronics
• Shortened title: IEEE j. sel. top. quantum electron.
• Publisher: IEEE
• ISSN: 1558-4542
• COBISS.SI-ID: 68843523

Licences

• License: CC BY 4.0, Creative Commons Attribution 4.0 International
• Link: http://creativecommons.org/licenses/by/4.0/
• Description: This is the standard Creative Commons license that gives others maximum freedom to do what they want with the work as long as they credit the author.

Secondary language

• Language: Slovenian
• Keywords: optične izgube širjenja, optično sipanje, kvantna fotonska integrirana vezja, viseči trakasti valovodi iz galijevega arzenida (GaAs), hrapavost stranic valovoda, hrapavost površine valovoda, delci na površini valovoda, nosilni mostiči valovoda