Fiber-to-silicon photonics interposer for high-density vertical coupling through laser structured mirror-waveguide circuits

Optical interposers are promising as a robust, reliable, and scalable technology for high-density coupling between the dissimilar platforms of optical fiber and silicon photonics (SiP) chips. To extend this concept, femtosecond laser micro-structuring was harnessed to develop a multi-level, mirror-waveguide optical circuit platform in fused silica glass. The flexible laser writing facilitated compact, low-profile vertical interconnection between multi-core fibers and SiP circuits, exploiting total internal reflection mirrors and vertical grating couplers. Various design strategies of laying out 3D waveguide fanouts, multi-core fiber sockets, and turn-mirrors were explored in 40 channel systems. The flexible interposer technology is scalable to higher channel counts, while maintaining a small footprint, thus offering a broad solution to challenges in areas of optical interconnects and photonic packaging.