Photon band gap properties and omnidirectional reflectance in Si/SiO2 Thue-Morse quasicrystals

Aperiodic one-dimensional Si/SiO2 Thue-Morse (T-M) multilayer structures have been fabricated in order to investigate both the band gap properties with respect to the system size (band gap scaling) and the omnidirectional reflectance at the fundamental optical band gap. Variable angle reflectance data have experimentally demonstrated a large reflectance band gap in the optical spectrum of a T-M quasicrystal, in agreement with transfer matrix simulations. We explain the physical origin of the T-M omnidirectional band gap as a result of periodic spatial correlations in the complex T-M structure. The unprecedented degree of structural flexibility of T-M systems can provide an attractive alternative to photonic crystals for the fabrication of photonic devices. (C) 2004 American Institute of Physics.