Photonic gap in amorphous photonic materials

Summary form only given. It has been known that either periodic or quasi-periodic photonic crystals can have photonic gaps. In these crystals both long-range and short-range orders exist. However, for the electronic analogs, only short-range order is necessary for the creation of energy gaps of electrons. It has been verified that the random dielectric structures do not possess spectral gap. Then the question naturally arises. If a dielectric structure possesses only the short-range order, does there exist spectral gap? Here, we name these dielectric materials as amorphous photonic materials (APM). The study of the APM may reveal what kind of roles the short-range order plays in the formation of spectral gaps.