Characterization of internal order of colloidal crystals by optical diffraction

We report the results of the optical characterization of photonic crystals consisting of close-packed arrays of polymeric monodispersed microspheres. The excellent agreement of the diffraction peak wavelengths with Bragg's law enables a precise determination of the sphere diameter. Optical diffraction is used to assess the quality of the internal order of colloidal crystals and to identify optimum growth conditions. This work leads to an estimate of the average free propagation distance of light, which is limited by incoherent scattering due to lattice imperfections, of up to 30 lattice constants.