  We investigate the dispersion and transmission property of slow-light
coupled-resonator optical waveguides that consist of more than 100 ultrahigh-Q
photonic crystal cavities. We show that experimental group-delay spectra
exhibited good agreement with numerically calculated dispersions obtained with
the three-dimensional plane wave expansion method. Furthermore, a statistical
analysis of the transmission property indicated that fabrication fluctuations
in individual cavities are less relevant than in the localized regime. These
behaviors are observed for a chain of up to 400 cavities.
