Optical Design and Applications for Ion-Exchanged Glass Waveguide Circuits

Glass provides high-dimensional stability and flatness, enabling high-throughput electronic assembly with high-precision optical alignment for co-packaged optics (CPO) applications. Optical waveguides can be integrated in the glass core material by the thermal silver ion-exchange (IOX) process at temperatures around $350~^{\circ }$ C for fiber-to-chip connectivity. Currently available IOX glasses degrade due to ion mobility at operating conditions, so we designed a new glass composition enabling waveguides to be stable over a lifetime of five years at an elevated temperature of $85~^{\circ }$ C or higher without performance degradation, which could impact the integrity of the optical signal. The glass composition was optimized for thermal stability and low-loss IOX waveguides were fabricated with a propagation loss of only 0.034 dB/cm. Waveguide designs are studied and evaluated for waveguide crossings, high-density spacing, tight bends, high-optical power transmission, and polarization dependency. The waveguide technology is demonstrated for different applications, including glass waveguide bridge for fiber-to-chip coupling, multicore fan-out, optical waveguide shuffle, and an optical waveguide circuit for CPO with over 1024 waveguide interconnects.