ABSTRACT
There is a wide variety of proposals for implementations of slow-light effects, and many of them are described in the various chapters of this book. The physical implementations vary from system to system, and so do the mathematical formalisms used to describe the specific physical systems. However, it is also possible that one has two completely different physical slow-light systems, yet the mathematical framework describing the slowing and stopping of light is very similar. In this chapter, we present an example falling into this category. The two physically different slow-light systems are (1) semiconductor multiple quantum wells (QWs) (more specifically: Bragg-spaced multiple QWs, or BSQWs [1-16]) and (2) optical resonators (more specifically: side-coupled integrated spaced sequence of resonators with two waveguide channels, or two-channel SCISSORs [17,18]). In Figure 13.1, BSQWs are schematically shown as a sequence of thin semiconductor QWs, spaced by a distance a with a dielectric of refractive index nb between the wells. SCISSORs are sequences of ring-shaped dielectric optical microresonators coupled to two waveguides (Figure 13.2). Clearly, these are very different physical systems, and so onemay wonder in which sense slow-light concepts (i.e., the concepts for delaying, stopping, storing, and releasing light) can be similar or almost identical in these systems. The answer to this question lies in the fact that both systems can be viewed as physical realizations of one-dimensional resonant photonic bandgap structures (RPBGs). RPBGs differ from conventional (nonresonant) photonic bandgap structures in that each unit cell in the photonic lattice exhibits an optical resonance with a resonance frequency that is identical or at
least close to the Bragg frequency characterizing the optical lattice. In QWs, the optical resonance is taken to be the heavy-hole exciton resonance, while in SCISSORs we take one of the optical resonances of the microrings.
