Crosstalk and interconnection distance considerations for board-to-board optical interconnects using 2-D VCSEL and microlens array

We describe the design and experimental characterization of a substrate-mod e optical backplane using 0.5 -, 0.75- and 1-mm spacing two-dimensional (2- D) optical beam arrays. The system uses arrays of multiplexed holograms to implement free space board-to-board interconnects, and employs 250-mu m pit ch 2-D vertical-cavity surface-emitting lasers (VCSEL) and microlens array as a transmitter to provide 0.5- to 1-mm spacing 2-D beam array, operating at 850 nm. By comparing the optical beam properties at the detector plane i ncluding the spot size and power uniformity of the optical beam array, as w ell as signal-to-noise ratio (SNR), the maximum interconnect distances are justified. Furthermore, we point out the improvement of the throughput that can be achieved by 2-D crosstalk analysis within the same design concept. The results of crosstalk analysis obtained here can be used for application to the standard five-board free-space optical backplane system.