设计了一种基于正方形晶格二维光子晶体自准直效应的1×3分束器。使用平面波展开法对正方形晶格椭圆介质柱光子晶体进行分析，计算出其等频线，讨论自准直光波频率和传播特性。逆时针旋转椭圆介质柱到一定角度，同样使用平面波展开法计算其等频线并分析光波传播特性。根据以上分析，基于自准直效应，使用不同偏转角度的椭圆介质柱光子晶体设计出1×3分束器。使用时域有限差分法对工作状态下光波在分束器中的传播特性进行分析，并给出了电场分布图，实现了1×3分束功能。此结构的分束器期望能推进光子晶体在光集成回路中的应用。

A 1×3 splitter based on self-collimation in a two-dimensional square-lattice photonic crystal is presented. The frequency and the direction of propagation of the self-collimated beams in square-lattice photonic crystal composed of elliptical dielectric rods are obtained by the equal-frequency contours (EFC) which are calculated by plane-wave expansion (PWE) method. Then the elliptical rods are rotated counterclockwise and the EFC is caculated employing PWE method. Based on the above, a 1×3 splitter is realized by photonic crystals composed of elliptical rods with different orientation angles. The transmission characteristics of light in the splitter are analyzed via the finite-difference time-domain (FDTD) method, and the resulting electric fields are also given. It is concluded from the electric fields that a 1×3 beam splitter is realized. The proposed splitter is expected to promote the application of photonic crystals in optical integrated circuits.