Electro-optical printed circuit board (EOPCB)

Recently attention has been given to optical waveguides in order to elude the interconnect bottleneck caused by insufficient discrete copper wiring at the board-level. But the cost increase, due to additional manufacturing steps and equipment, are justifiable only for those applications where electronic interconnections are unable to perform satisfactorily. That's why the future high-performance board will most likely be a hybrid carrier which combines electrical and optical circuitry. This paper will introduce a suitable technology to generate multimode waveguides on standard base materials like FR4. Great importance has been attached to designing a manufacturing process for the optical layer, which is essentially compatible with conventional PCB production. The results of early characterizations encouraged us to pursue this technology. Our layout contains bent waveguides, optical bifurcations and even crosses, the latter being unthinkable in electrical wiring layout. We will also address concerns like sidewall roughness of the waveguide structures, propagation loss, thermal and environmental stability, etc. which all are significant to the high performance EOPCB.