Probing Structural Correlated Disorder with Photonic Transport

Abstract

Wave spreading has been widely studied in various disordered materials including quasiperiodic, amorphous, and completely random materials based on the spatial order. However, there is no clear observable mechanism connecting the underlying correlated disorder to wave transport. Here, we experimentally probe correlated disorder with different characteristic length scales in disordered materials by directly observing the photonic transport on a chip. The density of states of corresponding aperiodic structures shows different degrees of singularity, suggesting diverse behaviors of photons. By analyzing localization and transport properties of photons, we demonstrate that compared to the nearly ballistic transport in the quasiperiodic lattice with long-range order, photon behavior is partly destroyed from ballistic transport in amorphous lattices with short-range order while totally deviating from ballistic spreading in completely random lattices without spatial order. The spreading coefficient related to the photon variance represents an evident difference for correlated disorder with different characteristic length scales. The resolution of diverse transport behaviors is sufficient to distinguish different disorder types, suggesting an eligible identifier for disorder materials.