Silicon Photonics: Fundamentals and Devices

1.1 Introduction

Silicon is the material par excellence. It is the most widely studied material in the history of civilization. In fact, the present-day information age has dawned with an electronics revolution brought about by the maturity of silicon-based microelectronics.

The growth of the silicon industry follows the now-famous Moore's law, which states that the number of transistors in an integrated circuit chip doubles every 12 months (since revised to every 18 months). However, during the last few years there has been indication of the decline of Moore's law. There are doubts whether in future silicon-based integrated circuits (ICs) will deliver the same advantages and functionalities as shown today.

The weakest point of silicon is that proper light emitters and modulators cannot be realized by using it due to the indirect nature of its band gap. On the other hand, there is a steady increase in the area of photonics, in the form of optical communication and networking, optical information processing, and consumer electronics based on light. Present-day photonics relies on compound semiconductors and their alloys. Although discrete devices using these materials show very good performance, when it comes to integration of these devices, preferably on the same substrate, the levels of integration and performance are far below what has already been achieved in electronic integration. It is natural to expect that monolithic optoelectronic integrated circuits (OEICs) will provide ...