Density of states controls Anderson localization in disordered photonic crystal waveguides

We prove Anderson localization in a disordered photonic crystal waveguide by measuring the ensembleaveraged extinction mean-free path, e, which is controlled by the dispersion in the photon density of states DOS of the photonic crystal waveguide. Except for the very low DOS case, where out-of-plane losses are non-negligible, e can be approximated to be the localization length . The extinction mean-free path shows a fivefold variation between the lowand the high-DOS regime, and it becomes shorter than the sample length thus giving rise to strongly confined modes. The dispersive behavior of e demonstrates the close relation between Anderson localization and the DOS in disordered photonic crystals, which opens a promising route to controlling and exploiting Anderson-localized modes for efficient light confinement.