Disorder-induced multiple-scattering in photonic-crystal waveguides

Slow light in photonic-crystal waveguides (PhCW) is a promising solution for time-domain processing of optical signals and for the enhancement of nonlinear optical effects. Slow light regime is however strongly impacted by random fabrication imperfections and the resulting losses are a critical hurdle limiting the optical delays and the interaction lengths. Therefore perturbation theories have been developed to determine how this inevitable fabrication disorder impacts on the slow light propagation in periodic waveguides. However these studies are only valid for imperfections that hardly affect the propagating mode. In this paper, a new coupled-Bloch mode scattering formalism that overcomes the present limitations of perturbation approaches. The formalism takes into account multiple scattering, localization effects and out-of-plane leakage, and allows a quantitative prediction of all the statistical transport coefficients, including averaged values as well as probability distributions.