Broadband intensity correlations in random, quasiperiodic and periodic photonic materials

Broadband optical correlation studies are incredibly useful tools to characterize key optical parameters of opaque scattering media. By shining a broadband-tunable near-infrared (NIR) beam on a sample, we capture momentum-space intensity speckle patterns as a function of frequency and sample position. Spectral correlations are intrinsically linked to the dynamic transport of light, namely the diffusion constant of light. Spatial correlations, on the other hand, are associated with static light transport, and used to determine the mean free path. By combining these measurements, we obtain the energy velocity of light inside the medium at various frequencies. We report studies of structurally very different samples, ranging from random samples (ZnO scatterers) for which theory is known, to quasiperiodic photonic quasicrystals and even fully periodic photonic band gap crystals, where remarkable non-traditional correlations are observed.