传统的WDM（波分复用器）通常尺寸较大，这一缺陷成了光子集成化的“瓶颈”。文章利用光子晶体的多模干涉效应设计了一种光子晶体三波长(1 310、1 490和1 570 nm) WDM。仿真结果表明，该器件对3个波长的插入损耗均小于0.45 dB，通道隔离度均大于15 dB；且尺寸仅为 37 μm×3 μm，易于光学集成，性能优良。

The conventional WDM are usually large in size, which has become the bottleneck of the photonic integration. This paper designs a type of threewavelength (1 310 nm, 1 490 nm and 1 570 nm) photonic crystal WDM by utilizing the multimode interference effects of photonic crystals. The simulation results show that the insertion loss of this device for the three wavelengths is all less than 0.45 dB, and the channel isolation is all larger than 15 dB. In addition, its size is only 37 μm×酞?3 μm. easy to be optically integrated and superb in performance.