High-speed wide band board-to-board optical interconnection

Abstract

Increases in modulation speed and interconnection distance have driven electrical interconnects to their theoretical limits, beyond which optical interconnections are the only possible alternative. In this paper, we report, we believe for the first time, a 14-GHz board-to-board optical interconnection. The optical data bus boards were constructed by depositing a graded-index (GRIN) polymer film on tope of a substrate. Thanks to the GRIN characteristic of the polymer film, an array of high-index substrates can be employed as the optical data bus boards. The propagation loss of the optical data bus was measured by the two prism method. We routinely achieved ~0.5 dB/cm propagation loss on various substrates. Board to board optical interconnection was achieved using a microprism array as small as 100 µm with a coupling bandwidth larger than 800 nm, which is two orders of magnitude larger than the 3-D optical interconnects based on holographic optical elements. A 1-GHz baseband signal was provided using an external modulator. Finally, the high-speed signal was detected by integrating a photodetector at the end face of the output microprism.