Distributed and localized feedback in microresonator sequences for linear and nonlinear optics

Sequences of optical microresonators can be used to construct densely integrated structures that display slow group velocity, ultrahigh or low dispersion of controllable sign, enhanced self-phase modulation, and nonlinear optical switching. We consider four archetypal geometries consisting of effectively one-dimensional sequences of coupled microresonators. Two of these cases exhibit distributed feedback such as is found in a traditional multilayered structure supporting photonic bandgaps. The other two exhibit localized feedback and resonant enhancement but are free from photonic bandgaps. All of these structures offer unique properties useful for controlling the propagation of light pulses on a chip.