PhD defence by Chaochao Ye

Abstract

Integrated nonlinear photonics has developed into a highly active research area over the past decades, opening new horizons in a wide range of applications. To date, various nonlinear material platforms have been explored. This thesis focuses on the development of an ultra-efficient aluminum gallium arsenide-on insulator (AlGaAsOI) integrated nonlinear platform.

One aspect of the research involves the fabrication of ultra-low loss AlGaAsOI devices. By optimizing the fabrication process, we successfully attained the highest quality factor for high-confinement III-V microresonators fabricated through an electron-beam lithography-based patterning process. Another aspect of the research focuses on dispersion management in multimode microresonators. We introduce a robust multimode waveguide design and a tapered coupler design that effectively suppress the unintended avoided mode crossing in AlGaAsOI microresonators. The final part of the research aims to enable efficient nonlinear processes in the AlGaAsOI platform. We successfully achieved an enhanced four-wave mixing process based on a bandstructured Fabry-Perot Bragg grating cavity, widely separated Kerr optical parametric oscillation utilizing higher-order dispersion, and room-temperature microresonator based dissipative Kerr soliton generation in both normal and anomalous dispersion regimes.

In summary, we comprehensively investigate the AlGaAsOI integrated nonlinear photonics, covering aspects of fabrication, theory, design, and applications, and provide insights into future development. We expect that the advancements achieved here will further prompt the development of AlGaAsOI integrated nonlinear photonics.

Supervisors

• Principal supervisor: Senior Researcher Minhao Pu, DTU Electro, Denmark
• Co-supervisor: Professor Kresten Yvind, DTU Electro, Denmark

Evaluation Board

• Senior Researcher Mikkel Heuck, DTU Electro, Denmark
• Professor Tobias Herr, Universität Hamburg, Germany
• Professor Jing Xu, Huazhong University of Science and Technology, China

Master of the Ceremony

• Senior researcher Hao Hu, DTU Electro, Denmark