Optical interconnections for digital systems

The replacement of electrical lines and connectors by free-space or guided-wave optics in high-performance digital systems is currently of active research interest. As clock rates approach or exceed 1 GHz, as the wiring density required by integrated circuits exceeds the capability of wire bonders, or as size, weight, and immunity to electromagnetic interference become issues, optical interconnections become an increasingly attractive alternative to electrical interconnections. Optical interconnections with only a laser, two lenses, and a detector are possible, and such a free-space board-to-board interconnection has been demonstrated at 1 Gb/s with an average power dissipation of only about 40 mW. Optical interconnections have prospects for even better performance with improved devices and should facilitate the development of advanced digital systems, particularly if the technology can be made cost effective