Silicon Photonics: Fundamentals and Devices

13.1 Introduction

Many planar lightwave circuits using optical waveguides and other devices are made by using silicon as the substrate. It is to be noted that planar and channel guide integrated optics are both analogous to very large-scale integrated (VLSI) electronics. In both circuits and systems, the main aim is to fabricate a large number of miniaturized interconnected devices on a single substrate. The processing of planar lightguides is very similar to the fabrication of VLSI devices, and both methods employ similar equipment. There are a number of advantages to using silicon. For example, the material silicon is obtained in large wafers, having diameters as large as 300 mm in 2005. Silicon is cheap, and thanks to decades of research, development, and manufacturing of microelectronics technology, Si-based lightwave circuits possess the same advantages, such as low cost, high reliability, and ability to be batch-fabricated. Also, the developed photonic devices may be readily integrated with electronic components grown on the same substrate.

In this chapter, we discuss some of the commonly used methods for fabrication of optical waveguides in silicon. Since the number of devices formed is quite large, the fabrication methods are widely different. We shall outline the most commonly used methods and briefly describe some of the special methods.

As noted already, techniques to fabricate Si-based lightwave circuits rely heavily on present-day electronics technology. We shall start ...