We study numerically the density of optical states (DOS) in two-dimensionalphotonic structures with short-range positional order, and observe a cleartransition from polycrystalline to amorphous photonic systems. In polycrystals,photonic band gaps (PBGs) are formed within individual do- mains, which leadsto a depletion of the DOS similar to that in periodic structures. In amorphousphotonic media, the domain sizes are too small to form PBGs, thus the depletionof the DOS is weakened significantly. The critical domain size that separatesthe polycrystalline and amorphous regimes is determined by the attenuationlength of Bragg scattering, which depends not only on the degree of positionalorder but also the refractive index contrast of the photonic material. Evenwith relatively low refractive index contrast, we find that modest short-rangepositional order in photonic structures enhances light confinement viacollective scattering and interference.
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