Method and Structure for Optical Coupling in Photonic Integrated Circuits Using Etched Silicon Substrates

This invention introduces a novel method and structure for optical coupling in photonic integrated circuits (PICs) using etched silicon substrates. These etched features allow light to be introduced from beneath the substrate and efficiently coupled into on-chip waveguides. It enhances the efficiency of photonic couplings, allowing multiple input modes to be excited with high density while reducing the overall size of the system. The approach leverages total internal reflection-based coupling, improving integration and performance within PICs. By eliminating the need for patterned gratings and enabling large-scale, efficient optical coupling, this invention enhances the packaging and performance of PICs, reducing insertion losses and simplifying fabrication.
 
Background: 
Photonic integrated circuits (PICs) play a crucial role in modern optical communication, computing, and sensing applications. However, a key challenge in their development is achieving efficient and compact optical coupling that supports high-density input modes. Existing solutions often struggle with integration efficiency and scalability. Traditional grating couplers suffer from limited coupling efficiency, spectral sensitivity, polarization dependence, and complex fabrication requirements. They also generally allow coupling into only one or a few waveguides at a time, restricting scalability in multi-channel systems. This invention addresses these limitations by introducing a silicon-on-insulator (SOI)-based coupling technique that enhances light transfer efficiency while minimizing space requirements.

Applications:

• High-speed optical communication networks
• Quantum computing and quantum photonics
• Optical interconnects for data centers
• LIDAR and sensing applications
• Biomedical imaging and diagnostics

Advantages:

• Enhances optical coupling efficiency through total internal reflection-based design
• Compact design reduces the size of photonic couplings, enabling higher integration density
• Supports high-density multi-mode excitation, improving PIC scalability
• Minimizes energy losses during optical coupling, enhancing overall performance
• Versatile; compatible with various photonic technologies, including silicon-on-insulator platforms