Study on random network photonic materials

研究了一种新型光子结构“光子非晶金刚石（PAD）”的光子带隙（PBG）形成和光传播特性。首先，在完全没有晶格周期性的情况下，实验证明了一个完整的三维（3D） PBG的形成。三维PBG在PAD中被证明是干净的，没有局域光子态的痕迹。干净的三维PBG应该能够在PAD中实现强光约束，这已经在数值上得到了证明。PAD中的三维PBG是完全各向同性的，不受光波方向和偏振方向的影响，这在传统光子晶体中原则上是无法实现的。在通带中，PAD表现为漫射光传播，当频率接近带边缘时，散射强度显著增加。在接近带边缘的频率范围内，散射强度很高，实现了光的定位。这些发现对PBGs的物理起源以及光子材料中的光扩散和局域化等问题提供了新的见解。

Photonic band-gap(PBG) formation and light propagation properties of a recently-proposed new-type photonic structure "photonic amorphous diamond(PAD)" are studied. First, the formation of a full three-dimensional(3D) PBG has been demonstrated experimentally, in spite of complete absence of lattice periodicity. The 3D PBG in PAD has been shown to be clean with no trace of localized photonic states within it. The clean 3D PBG should enable strong light confinement in PAD, which has actually been demonstrated numerically. The 3D PBG in PAD is completely isotropic, regardless of the light wavevector orientation and polarization direction, which, in principle, cannot be realized in conventional photonic crystals. In passbands, the PAD exhibits diffusive light-propagation, where the scattering strength increases significantly as the frequency approaches the band edge. In frequency ranges near the band edge, the scattering strength is so high that light localization is realized. These findings provide new insights into the physical origin of PBGs and issues such as light diffusion and localization in photonic materials.