Despite the widespread use of silicon photonics, fiber coupling remains a major challenge in mass production. Our group has demonstrated integrated microlens couplers (IMCs) as an efficient, broadband, and polarization-insensitive solution for wafer-scale fiber-to-chip coupling, with a previously achieved free-space loss of 0.6 dB.
In this project, we are transitioning from polymer-based to hard-material IMCs, fabricating microlens using SiON and utilizing anisotropic etching to transfer the lens pattern from PR to SiON. By optimizing the oxide-to-nitride ratio, we minimized film stress while maintaining the desired refractive index. We successfully deposited extra-thick (>20 μm), low-stress (bow <50 μm) SiON films via PECVD and developed etching recipes to fine-tune PR-to-SiON selectivity, ensuring precise pattern transfer with high shape fidelity.
These advancements significantly improve IMC durability during packaging, paving the way for a robust, pluggable fiber-to-chip connector for scalable silicon photonics integration.
Project is currently funded by: Industry Sponsored Research