Silicon Photonics - Fundamentals and Devices

There is no doubt that one of today's bottlenecks faced by IC designers is that of electrical interconnects. Electrical connections in integrated circuits introduce larger time delays than the gate delay itself and multilayered interconnections need insulators between them. Optical interconnections can solve both these problems (and partially also that of crosstalk); this is the motivation because silicon (Si) photonics came into play in the industry arena. Silicon, the most widely used material in electronics, does not find a large room in optoelectronics. The indirect nature of its band gap prevents the realization of efficient light emitting diodes (LEDs) or laser diodes; the absence of linear electro-optic effect stands in the way of achieving high-speed modulators using Si¬based materials; and, in addition, the band gap of Si does not match the standard wavelengths of $1.3\mu \mathrm{m}$ or $1.55\mu \mathrm{m}$ in present fiber optic telecommunications systems. Currently, there is one niche area in optoelectronics in which Si finds its place. This is the planar light wave circuits (PLCs) used in optical fiber communications. These include primitive devices like planar waveguides with silica-on-Si (SOS), silicon-on-insulator (SOI), directional couplers, Y-junctions, as well as more complex passive circuits like arrayed waveguide gratings, adddrop multiplexers and hybrid light wave circuits embodying light sources, light detectors, multiplexers and demultiplexers, and various other components. It is in this context that this book is developed in about 430 pages, 13 chapters and one appendix. This book is primarily a text with the targeted audience of senior undergraduates, graduate students, practicing engineers and technologists for whom introduction to basic principles and overall development in the field are important.