Wafer-scale statistical extraction of parallel waveguide spacing from optical resonant spectra

Area of Science:

• Photonics
• Integrated Optics
• Materials Science

Background:

• Photonic integrated circuits (PICs) are crucial for modern optical communication and computing.
• Precise control over waveguide spacing is essential for PIC performance but challenging to monitor during fabrication.
• Fabrication variations can significantly impact device functionality and yield.

Purpose of the Study:

• To develop a scalable and accurate method for extracting parallel waveguide spacing in PICs.
• To enable in-line process monitoring and variation-aware modeling in silicon photonics manufacturing.
• To visualize and quantify fabrication-induced variations across a wafer.

Main Methods:

• Design of high-sensitivity channel-ring resonators sensitive to waveguide spacing variations.
• Wafer-scale optical transmission spectra measurements of fabricated resonators.
• Application of a compact model to quantitatively link spectral response to effective waveguide gap.
• Generation of a virtual wafer map correlating resonator position with fabrication variations.

Main Results:

• Successful quantitative extraction of effective waveguide gap with high accuracy.
• Visualization of spatial distribution of fabrication-induced variations using virtual wafer maps.
• Experimental validation across diverse resonator array designs on a silicon photonics platform.
• Demonstration of statistical robustness for reliable process monitoring.

Conclusions:

• The presented method offers a precise and scalable solution for monitoring waveguide spacing in PIC fabrication.
• This approach facilitates in-line process control and supports variation-aware design and modeling.
• It provides a viable pathway to enhance yield and performance in photonic chip manufacturing.