Disorder effects in reflectance spectra of colloidal photonic crystals

Although fabrication of photonic crystals improved over the last few years, intrinsic defects of the crystal lattice affect the experimentally measured spectral features. In order to compare experimental spectra with simulated photonic band structure, disorder effects are simulated by introduction of material absorption. By using the finite-difference time-domain (FDTD) method we were able in the past to obtain a good agreement between experimental and simulated transmission curves by taking in account the glass substrate. In this work we extend our analysis for reflectance curves of one, two and three-layered close-packed polystyrene spheres. We show that a key ingredient in simulating disorder effects is the introduction of fictional absorption for polystyrene.