The following paper presents research on the manufacture of circuit boards with buried optical waveguides using thin-glass
sheets (display glass), which represents a further development of earlier research on buried optical waveguide
substrates using polymer. An ion-exchange process was developed to manufacture the waveguides in thin-glass sheets,
thereby eliminating the necessity of mechanically structuring the layers. The waveguide properties were simulated and
experimentally validated. The circuit board assembly and the concept for the optical coupling from the module to the
board and from the board to the backplane are presented. The design and assembly of pluggable electro-optical
transmitter and receiver modules is described.
Due to ever-faster processor clock speeds, there is a rising need for increased bandwidth to transfer large amounts of data, noise-free, within computer and telecommunications systems. A related requirement is the demand for high bit-rate, short-haul links. Here, optical transmission paths are a viable alternative to high-frequency electrical interconnections, whereby layers with integrated waveguides are particularly suitable. The reasons for this include that a higher connection density can be achieved and the power dissipation, as well as interference from electromagnetic radiation, are significantly lower. The article presents general considerations and the results of research conducted by the German BMBF Project NeGIT, into the manufacture of circuit boards with embedded polymer optical waveguides. The electrical-optical boards were fabricated using precise photolithographic processes and standard lamination methods. They possess the thermal stability necessary for manufacturing processes and operational conditions, in terms of both bond strength and the stability of the optical properties. As part of this project, a design of an optical coupling in the daughter card and board backplane interfaces was developed and is presented as the centerpiece of this study.