Influence of Disorder and Finite-Size Effects on Slow Light Transport in Extended Photonic Crystal Coupled-Cavity Waveguides

A convenient approach for slowing down light in integrated optical circuits is by utilizing a set of coupled microcavities in a photonic crystal lattice. While this provides for flexibility in dispersion engineering, light transport is influenced by a combination of disorder and finite-size effects, setting limitations on the achievable slow light properties. In this study, the experimental characterization of slow light photonic crystal waveguides based on a coupled-cavity design is presented in the near-infrared wavelength range for extended chains comprising up to 800 cavities. The dispersive behavior of light along the waveguides is probed through Fourier-space imaging to elucidate the influence of disorder and cavity chain length on the optical response of the implemented design. Constraints on the slow-down factor of Bloch modes are identified in terms of decay length and induced light localization.