运用平面波法研究了光波入射二维光子晶体时的模场分布,包括周期性结构、中心引入点缺陷和线缺陷三种情况。结果表明:对于完全周期性光子晶体,其模场是波矢量k的周期性函数;不同的k即使对同一个能带也存在不同的模场分布;模场主要分布在高介电常数的区域,且呈现高度对称性;除了简并模,相邻模场正交;模场分布形状与晶格结构有关,正方晶格模场呈现正方形分布;而对于不同的点缺陷,点缺陷半径不同,模场分布不同;当二维光子晶体中存在线缺陷时,其模场分布在缺陷及其周围的区域,呈现明显的周期对称性。 The mode field distribution of two-dimensional photonic crystal with light incident wave is studied by plane wave method, including periodic structure, point-in-center introduction and line-defect. The results show that for a completely periodic photonic crystal, the mode field is a periodic function of the wave vector k; different k have different mode field distribution even for the same energy band; the mode field is mainly distributed in the region of high dielectric constant , And showed a high degree of symmetry. In addition to the degenerate mode, the adjacent mode field is orthogonal; the mode field distribution shape is related to the lattice structure and the square lattice mode field presents a square distribution; for different point defects, the point defect radius is different, The distribution of mode fields is different. When there is a line defect in a two-dimensional photonic crystal, the mode field is distributed in the defect and its surrounding area, showing obvious periodic symmetry.