Silicon Nitride Foundry Process Delivers 9.3% Uniformity Across 46 Visible Grating Emitters

{"The architecture replaces binary trees with individually tuned coupler lengths that set arbitrary tap ratios, allowing uniform local intensity rather than far-field pattern optimization. Fabricated devices were measured under both narrowband 530 nm and 550-650 nm illumination, confirming 8.8% band-integrated variation. The 46-channel result directly addresses channel-count limits in multiplexed optical biosensors.","Conventional phased-array networks optimize aggregate beams; this work instead targets per-emitter power equality required for parallel sensing. The foundry run used standard silicon nitride thickness and etch steps, indicating immediate transferability to existing visible-photonics MPW shuttles. Coefficient-of-variation numbers were obtained from calibrated camera imaging of the grating outputs.","Related work on silicon-nitride visible platforms (e.g., LioniX and AIM Photonics process reports) has focused on ring resonators and AWGs; grating tap networks remain rare. The present design scales to hundreds of channels once coupler-length libraries are automated, opening parallel neural interfaces and quantum-control arrays previously constrained by illumination non-uniformity.","Next steps include on-chip reference detectors and closed-loop trimming to push variation below 5%. A 2025 tape-out incorporating active feedback would test whether the passive 9% floor is sufficient for most biosensing dynamic ranges or whether active compensation becomes necessary."}