Challenges and advances of photonic integrated circuits

The idea of Photonic Integrated Circuits (PICs) appeared in the 1970s, had first achievements in the 1980s with, for example, a laser–modulator. However, recently, due to the demand for increasing bandwidth (100 Gb/s) at lower cost and consumption, and due to semiconductor optoelectronics processing maturity, extremely complex PICs have been developed and industrially produced. This dense integration is an important technological breakthrough, and has a strong impact on optical communication systems with for example cost-effective O/E/O nodes, or transmissions with new modulation formats. This article presents the technological challenges related to PICs, and the major realizations made, up to today.