Kurt Hamza, Citrin D S
Opt Express. 2005 Dec 12;13(25):10316-26. doi: 10.1364/opex.13.010316.
A new type of two-dimensional photonic-crystal (PC) structure called annular PC composed of a dielectric-rod and a circular-air-hole array in a square or triangular lattice such that a dielectric rod is centered within each air hole is studied. The dielectric rods within the air holes greatly modify the dispersion diagram of the photonic crystal despite the fact that the percentage of volume occupied by the dielectric rods may be small (<12%). Increasing the radius of the inner-dielectric rod, starting from zero to a critical value, reduces the band gap and closes it completely as expected, because of the addition of more dielectric material inside the unit cell. Continuing to increase the radius of the rod above the critical value surprisingly creates another photonic band gap. Comparison of the dispersion diagrams of the new structure and the original lattice (circular air hole square/triangular array in dielectric background) reveals that the photonic band gap is considerably enhanced in size for both square and triangular lattice with the new structure. This approach preserves the symmetry of the structure and provides a complete photonic band gap away from the close-packed condition and at low normalized frequencies.
研究了一种新型二维光子晶体（PC）结构，称为环形光子晶体，它由介电棒和方形或三角形晶格中的圆形气孔阵列组成，使得介电棒位于每个气孔的中心。尽管介电棒所占体积百分比可能很小（<12%），但气孔内的介电棒极大地改变了光子晶体的色散图。从零开始增加内介电棒的半径到一个临界值，如预期的那样会减小带隙并使其完全关闭，这是因为在晶胞内添加了更多的介电材料。继续将棒的半径增加到临界值以上，令人惊讶的是会产生另一个光子带隙。新结构与原始晶格（介电背景中的圆形气孔方形/三角形阵列）的色散图比较表明，对于具有新结构的方形和三角形晶格，光子带隙的尺寸都有显著增强。这种方法保持了结构的对称性，并在远离密堆积条件和低归一化频率下提供了完整的光子带隙。
