Parallel optical interconnections for future broad band systems, based on the "fibre in board technology"

A novel interconnection technology based on the integration of glass optical fibres in a standard printed circuit board is presented to overcome the interconnection bottleneck in the nest generation of broad band switching fabrics. Within these systems, the parallel electro-optical modules will be: integrated on the switching board itself which has a switching capacity of 20 Gbit/s. A robust and automated technology is used for the realisation of optical interconnections between these electro-optical (E/O) modules and the off-board connectors at the edge of the board. Dedicated surface optical contacts have been developed, capable of handling 16 parallel channels. These surface optical contacts can be integrated everywhere on the board and can be used for mounting an electro-optical module or a multifibre connector compatible with this technology. Electro-optical modules (8 channel transmitters and 4 channel receivers) and multifibre optical back panel connectors have been integrated on an engineering prototype for the evaluation of the technology. Off-board links, over 200 m MM (graded index) fibre, and on-board links are operational at 622 Mbit/s. The boards have been subjected to reliability tests and preliminary results reveal no degradation of the board after thermal cycling. Precision moulding techniques are presented to make the proposed technology more cost-effective and suitable for volume production.