Experimental observation of strong photon localization in disordered photonic crystal waveguides

TL;DR

This paper reports the experimental observation of strong photon localization in disordered photonic crystal waveguides, revealing sharp resonances and high Q-factors indicative of Anderson localization effects.

Contribution

It provides the first experimental evidence of Anderson localization of photons in disordered photonic crystal waveguides with high Q resonances.

Findings

Sharp resonances with Qs over 30,000 observed

Localization occurs within a 20-nm bandwidth at mode cutoff

Spectral features match interference-based localization theory

Abstract

We demonstrate experimentally that structural perturbations imposed on highly-dispersive photonic crystal-based waveguides give rise to spectral features that bear signatures of Anderson localization. Sharp resonances with the effective Qs of over 30,000 are found in scattering spectra of disordered waveguides. The resonances are observed in a ~20-nm bandwidth centered at the cutoff of slowly-guided Bloch-modes. Their origin can be explained with interference of coherently scattered electromagnetic waves which results in the formation of a narrow impurity (or localization) band populated with spectrally distinct quasistates. Standard photon localization criteria are fulfilled in the localization band.