理论设计了一种金属-介质-金属(MIM)双缝结构的表面等离子体可见光分光器。利用表面等离子体效应及经典光学干涉原理，改变双缝波导结构中的填充介质、结构厚度、狭缝宽度、双缝宽度等参数，可使波长不同的两束可见光通过双缝亚波长结构后实现表面等离子分束的效果。设计过程中采用时域有限差分法(FDTD)进行数值模拟，分别模拟计算了双缝宽度相同填充介质不同和双缝填充介质相同宽度不同两种情况下的光场分布，且都得到了较好的分束效果，最大分束比可达12。该设计结构简单，可以通过电子束刻蚀系统等实验设备加工，具有较好的应用前景。

The model of plasmonic dichroic splitter in metal-insulator-metal (MIM) stucture with two subwavelength metallic slits is proposed in theory. The different visible lights passing through the double slits subwavelength structure produce optical splitting effects by filling with different insulators and setting the slit width, double slits width and thickness of the waveguide structure of double slit. The splitting effects are explained by using surface plasmon′ s principle and classical optics interference principle. Finite-difference time-domain (FDTD) method is adopted for numerical simulation. We simulate the light filed distribution in two cases of double slits with the same width filled in different insulators and the double slits with different width filled in same insulators. Both cases can achieve ideal splitting effects, and the biggest splitting ratio is 12. The MIM design has the advantage of simple structure, can be obtained by electron beam lithography system experiment equipment. Therefore, it has good application value.