Polymers of differing refraction indices are embedded within a PCB to provide
optical connectivity of the PCB with other circuit boards via an optic backplane.
The creation of islands of polymer material of refractive index n1 completely
surrounded by polymer material with refractive index n2 where n1
has a higher index than n2 allows the islands of n1 indexed polymer
to serve as optical waveguides. A process of forming a multi-layered PCB with the
optical waveguide islands using successive laminations and using laser ablation
to write the optical connection scheme is taught. Further, the use of uniquely
marked targets in a copper layer to align the optical waveguides in production
is also taught. Additionally, the use of clearing polymer materials and reinforcing
polymer voids with lamination to allow a simple, high tolerance insertion of through-holes
is taught.