Measurement of group velocity dispersion for finite size three-dimensional photonic crystals in the near-infrared spectral region

We measure group delay and group velocity dispersion of silica colloidal photonic crystals in the near-infrared with white light interferometry. While group delay and group velocity dispersion increase with sample thickness, scattering on sample imperfections is found to counteract this development, resulting in group delays lower than theoretically expected. For thin photonic crystals, group velocity dispersion imposed by Fabry-Perot oscillations is as strong as the one resulting from the periodicity. Group velocity dispersions as high as 30 ps(2) m(-1) are observed. All measurements are in good quantitative agreement with numerical calculations. (C) 2005 American Institute of Physics.