The concept of a three-dimensionally interconnected optical backplane for a high-performance system containing multichip module boards, operating at 850 nm, is introduced. The backplane reported here employs 2-D vertical-cavity surface-emitting lasers (VCSELs) and photodetector arrays as transceivers. By integrating 250-^m-pitch 2-D VCSELs, microlenses, and photodetector arrays into our backplane design, we have demonstrated a multi-bus-line optical backplane and experimentally realized this architecture with 2-D VCSEL and detector arrays while using the third dimension as the signal-propagating direction. Such an approach greatly increases the aggregate bandwidth of the backplane. Packaging issues such as misalignment, cross talk, and signal-to- noise ratio are studied. Eye diagrams up to 1.5 GHz were obtained with clear eyes, and the frequency response of a single bus line shows a bandwidth of 2.5 THz.