Large Optical Backplane With Embedded Graded-Index Glass Waveguides and Fiber-Flex Termination

Introduction of electro-optical circuit board (EOCB) technologies based on embedded glass waveguides in the system enclosure of current data storage, compute, or switch platforms will be instrumental in accommodating the prohibitive bandwidth densities projected in exascale data centers, access networks, and high-performance computing environments in future. The main focus of this paper is, therefore, on the realization of large EOCB backplanes (350 × 465) mm
²
with passive dual-star interconnect topologies. The waveguides are embedded inside glass panels using a two-step thermal ion exchange process. The fabricated embedded waveguides are then characterized for propagation and coupling losses across different wavelength ranges and for different coupling arrangements. The fabrication process for these large panels is briefly explained accompanied by the lamination process of four separate glass panels. The connectivity between backplane and peripheral cards is addressed using fiber flex termination with two possible waveguide interfaces-actively assembled pluggable interface and passively assembled adhesive bonded interface. A demonstration platform is also finally reported and the viability evaluated for optical connectivity and system efficiency is tested for the whole system containing fiber flex termination.