Breaking through the barriers [semiconductor lasers]

In this era of high-end microelectronic integrated-circuit processing there are numerous examples of practical circuit designs containing many tens of thousands of transistors. The state-of-the-art for semiconductor photonic integrated circuits-those in which the information is carried entirely by optical rather than electrical signals-has been limited, however, to only a handful of devices. This article outlines two of the critical barriers to photonic integration and describes some recent advances in the technology that contribute to overcoming those barriers. Some examples of the implementation of these technologies are also presented