Stitching-loss-tolerant silicon nitride waveguides on glass for panel-level optical interconnects

Area of Science:

• Materials Science
• Optical Engineering
• Nanotechnology

Background:

• Reticle stitching in i-line stepper lithography causes optical loss in silicon nitride (SiN) waveguides.
• This loss is a critical bottleneck for cost-effective, large-area fabrication of optical interconnects.

Purpose of the Study:

• To propose and demonstrate a stitching-loss-tolerant SiN waveguide structure.
• To mitigate optical loss introduced during the fabrication process.

Main Methods:

• Fabrication of SiN waveguides using i-line stepper lithography.
• Measurement of optical loss at stitching interfaces for straight and tapered waveguide designs.
• Characterization of stitching loss with varying tapered waveguide stitching widths (Ws).

Main Results:

• Straight SiN waveguides exhibited a stitching loss of 0.105 dB/interface at 1310 nm.
• Tapered waveguides with Ws of 2 µm and 3.5 µm showed significantly reduced losses of 0.0678 dB/interface and 0.0213 dB/interface, respectively.
• The proposed structure effectively alleviates stitching-induced optical loss.

Conclusions:

• The developed stitching-loss-tolerant SiN waveguide structure is effective in reducing fabrication-related optical losses.
• This advancement supports the realization of cost-effective, glass-based panel-level optical interconnects.
• The findings address a key challenge in next-generation optical packaging.