Silicon Nitride Integrated Photonics from Visible to Mid‐Infrared Spectra

Abstract Silicon nitride (Si 3 N 4 ) photonic integrated circuits (PICs) are of great interest due to their extremely low propagation loss and higher integration capabilities. The number of applications based on the silicon nitride integrated photonics platform continues to grow, including the Internet of Things (IoT), artificial intelligence (AI), light detection and ranging (LiDAR), hybrid neuromorphic and quantum computing. It's potential for CMOS compatibility, as well as advances in heterogeneous integration with silicon‐on‐insulator, indium phosphate, and lithium niobate on insulator platforms, are leading to an advanced hybrid large‐scale PICs. Here, they review key trends in Si 3 N 4 photonic integrated circuit technology and fill an information gap in the field of state‐of‐the‐art devices operating from the visible to the mid‐infrared spectrum. A comprehensive overview of its microfabrication process details (deposition, lithography, etching, etc.) is introduced. Finally, the limitations and challenges of silicon nitride photonics performance are pointed out in an ultra‐wideband, providing routes and prospects for its future scaling and optimization.