Glass substrates for photonic integrated circuits

Abstract

Described herein are glass substrates that include a cavity and glass fingers extending into the cavity. A photonic integrated circuit (PIC) is positioned near the cavity such that a waveguide of the PIC is optically coupled to a waveguide of the glass substrate formed in one of the glass fingers. The structure described herein allows for improved coupling efficiency between the PIC and the glass substrate, and improved access for underfill and outgassing processes. This approach facilitates reliable packaging of large or multi-reticle PICs while maintaining high optical and mechanical performance.