US Patent 10439720 FPC-based optical interconnect module on glass interposer

FPC-based optical interconnect modules with glass interposer connecting a VCSEL laser to a fiber ribbon cable is described. Improved optical coupling between VCSEL/PD and polymer waveguides are achieved by monolithically integrating micro-lenses and waveguides on the rear side of glass interposer and active devices on the front side. The waveguide has a vertical portion at one end of a horizontal trench portion joined by a 45 degree sidewall. A method of fabrication includes: providing a glass interposer, an array of micro lenses and an array of polymer waveguides having 45 degree tapered ends as reflectors on one surface, and depositing a metal layer and patterning the metal layer into transmission lines on the second surface of the glass substrate, growing bonding pillars for flip chip mounting and assembling active optical devices on the second surface of the glass to connect with the transmission lines.