<title>256-channel bidirectional optical interconnect using VCSELs and photodiodes on CMOS</title>

2D Parallel Optical Interconnects are capable of providing large connectivity between elements in computing and switching systems. Using this technology we have demonstrated a bi-directional optical interconnect between two PCBs containing optoelectronic VLSI circuits. The OE- VLSI circuits were constructed using VCSELs and photodiodes flip-chip bump bonded to a 0.35 micrometers CMOS chip. The CMOS was comprised of 256 Vertical Cavity Surface Emitting Laser (VCSEL) drivers, 256 receivers, and the requisite buffer and control circuits required to operate the large transceiver array. This is the first system, to our knowledge, to send bi-directional data optically between optoelectronic VLSI chips which have both VCSELs and photodiodes co-integrated on the same substrate.