Silicon photonics is an evolving technology in which data is transferred among computer chips by optical rays. Optical rays can carry far more data in less time than electrical conductors.
Optical fibre is being used to overcome the limitation of copper in networking and storage area networks (SANs) to support faster interconnects between data centers. The next threshold in performance is the connectivity between chips and processors. The concept involves combining laser and silicon technology on the same chip. The improved performance results from the greater available bandwidth and higher propagation speed of infrared (IR) beams compared with electric current. The effective implementation of silicon photonics technology would dramatically increase the processing speed and power of computers.
Silicon photonics research began in the late 1980s and has been ongoing ever since. The technology uses lasers to transfer data into light pulses. A multiplexer combines the pulses into a single signal which travels across a optic fiber to a silicon receiver where de-multiplexers divide the signal back into separate channels. Photodetectors can then turn the light back into data.
Historically, one of the most serious challenges facing the developers of silicon photonics has been the fact that laser devices, which generate the IR beams that carry the data, are power-hungry. In addition, silicon has not proven effective for lasing because of thermal dissipation within the material. For these reasons, external lasers have been required in the manufacture of optical computers using silicon chips. Researchers are developing methods of overcoming problems that prevent the use of silicon, however. For example, combining silicon with indium phosphide improves its IR-transmission capacity. Electric current is applied to the indium phosphide through metal electrodes, causing photon emissions that can be confined and concentrated in a silicon cavity, producing coherent IR.