Directional Multiplexing for optical Board-to-Board Interconnections

The propagation angle of a beam is conserved when traveling through a multi-mode step-index fiber over short distances. We show that this feature can be used for multiplexed signal transmission thus providing a high bandwidth single-fiber interconnection between chips, boards or racks. With respect to this application the transmission properties of a fiber are analyzed. Concepts for optical multiplexing and de- multiplexing set-ups are outlined. A fiber transmission line consisting of a fiber and an optical de-multiplexing unit is characterized to obtain experimental results on the transmission capabilities in terms of efficiency, channel separation, number of multiplexed channels and cross-talk