Abstract
A recently proposed photonic bandgap material, named “photonic amorphous diamond” (PAD), was fabricated in a terahertz regime, and its terahertz-wave propagation properties were investigated. The PAD structure was fabricated from acrylic resin mixed with alumina powder, using laser lithographic, micro-additive manufacturing technique. After fabrication, the resulting structure was dewaxed and sintered. The formation of a photonic bandgap at around 0.45 THz was demonstrated by terahertz time-domain spectroscopy. Reflecting the disordered nature of the random network structure, diffusive terahertz-wave propagation was observed in the passbands; the scattering mean-free path decreased as the frequency approached the band edge. The mean-free paths evaluated at the band edges were close to the Ioffe-Regel threshold value for wave localization.
Highlights
A recently proposed photonic bandgap material, named “photonic amorphous diamond” (PAD), was fabricated in a terahertz regime, and its terahertz-wave propagation properties were investigated
Because Bragg scattering of light due to lattice periodicity has been considered to be the main origin of bandgap formation, it was commonly believed that lattice periodicity is indispensable for the realization of 3D photonic bandgap (PBG)
It was recently demonstrated, by numerical simulation, that a 3D amorphous structure with no trace of lattice periodicity can form a sizable, complete 3D PBG,4 and that strong light confinement is realizable in the amorphous structure as well as in conventional photonic crystals
Summary
A recently proposed photonic bandgap material, named “photonic amorphous diamond” (PAD), was fabricated in a terahertz regime, and its terahertz-wave propagation properties were investigated. Because Bragg scattering of light due to lattice periodicity has been considered to be the main origin of bandgap formation, it was commonly believed that lattice periodicity is indispensable for the realization of 3D PBGs. it was recently demonstrated, by numerical simulation, that a 3D amorphous structure with no trace of lattice periodicity can form a sizable, complete 3D PBG,4 and that strong light confinement is realizable in the amorphous structure as well as in conventional photonic crystals.5 This amorphous structure consisted of a random network of dielectric rods with a diamond-like local tetrahedral configuration and was named “photonic amorphous diamond” (PAD).
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