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光子能带结构中的狄拉克点是目前光子晶体研究中新兴的热点。选用双轴材料,用六边形介质柱构成了六角晶格各向异性光子晶体。该光子晶体有三个各异的主介电常数εxx、εyy、εzz。依据麦克斯韦方程组,垂直极化(TE)波中的狄拉克点会受到εxx≠εyy的影响,即可以通过调制双轴材料中X、Y方向的主折射率Nx、Ny得到光子晶体中TE波的狄拉克速率,从而调节TE波中狄拉克点在能带结构图中的位置(即调节狄拉克点的归一化频率及其在布里渊区的位置)。研究了Nx、Ny(对应εxx、εyy)与TE波中狄拉克点的存在性的关系,并通过仿真实验验证了提出的观点。这些研究可为研发新型光学器件以及构建光子芯片提供更多的可能。
Dirac points in the photonic band structure are emerging hot spots in photonic crystal research. The use of biaxial materials, hexagonal dielectric column formed hexagonal crystal anisotropic photonic crystal. The photonic crystal has three different main permittivities εxx, εyy, εzz. According to the Maxwell’s equations, the Dirac points in the vertical polarization (TE) wave are affected by εxx ≠ εyy, that is, the TE wave in the photonic crystal can be obtained by modulating the principal refractive indices Nx and Ny in X and Y directions of the biaxial material The Dirac velocity is adjusted to adjust the position of Dirac points in the TE band (ie, the normalized Dirac point and its position in the Brillouin zone). The relationship between Nx, Ny (corresponding to εxx, εyy) and the existence of Dirac points in TE waves is studied. The proposed viewpoint is verified by simulation experiments. These studies provide more possibilities for developing new types of optics and for building photonic chips.