Axel Beier

Waveguide and packaging technology for optical backplanes and hybrid electrical-optical circuit boards

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.

Thin glass based electrical-optical circuit boards (EOCB) using ion-exchange technology for graded-index multimode waveguides

The concept and experimental results to manufacture electrical-optical circuit boards (EOCB) with buried optical waveguides using thin-glass sheets (display glass) are presented. An ion-exchange process was developed to manufacture the graded index waveguides in thin-glass sheets. Besides of their excellent optical properties no mechanical structuring is necessary for the waveguides. Their properties were simulated and experimentally validated. The circuit board assembly is presented, as well as the concept developed for the optical coupling in the module-to-board and board-to- backplane coupling, and the assembly of the pluggable electrical-optical module itself is described.

New-generation interconnect

A new-generation interconnect for optical backplane systems based on printed circuits board is presented for transmitting data via integrated multimode polymer optical waveguides both on electro-optical transmitter/receiver processing boards and on optical backplane board. Different developments concerning this system such as optical waveguide technology, transmitter/receiver module activities, and optical interconnect/coupling concepts are discussed.

Electro-optical circuit boards using thin-glass sheets with integrated optical waveguides

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.