An integrated free space optical bus

As integrated circuit linewidths are reduced, single-chip system functionality and speed increase. Conventional electronic chip input/output does not follow this trend: bonding pad sizes and off chip capacitive loads remain essentially constant. Shortage of chip interconnect capability has become critical. Integrated free-space optical interconnect has the potential to overcome this problem by providing a large number of high-speed connections between chips. A description is given of the application of free-space optics, quantum-well modulators, and CMOS photodetectors to this task