chapter  25
40 Pages

Design and Applications of Photonic Crystals

Throughout the last two decades, there has been significant activity in the development of photonic devices that can confine, control, and route light on a scale comparable to modern electronic devices, namely the nanometer scale. A key motivation for this is to realize photonic circuits having a density approaching that of modern electronic circuits. However, in order for this to be done, such devices would need the ability to confine light on a subwavelength scale and exist in a material compatible with the

microelectronics manufacturing infrastructure. Although the latter requirement was readily satisfied through a proper choice of materials, i.e., silicon, the former one was more elusive. The reason for this arose from the fact that reflective, or conducting, devices are very lossy at optical wavelengths and refractive, or total internally reflective, devices do not offer mode confinement on a small enough scale. For this reason, researchers turned to the field of photonic crystal (PhC) devices, and their associated photonic bandgap (PBG) devices, which offer both low loss and high confinement, and can be readily fabricated in silicon. However, before we begin discussing the various aspects of silicon-based PhCs, we first present a brief perspective on their current status.