采用有限时域差分法，研究了内嵌金属块长度与夹缝宽度对金属绝缘体金属波导结构的光透射特性的影响。研究发现，此结构相比较于单一直波导而言，出现了一个很明显的透射峰。并且当金属块的长度较大时，其与波导上表面的金属之间形成的夹缝会构成法布里珀罗腔，高阶共振模式被激发，能量在腔内不断谐振，从而产生多个不断衰减的共振峰。同时，提出了一种基于内嵌双金属块结构的表面等离激元带通滤波器，此滤波器在共振峰以外波段的透射率可以下降为0，且其共振波长可以通过改变金属块的长度等参数进行调节。

The effects of the length of the embedded metal strip and the width of the gap in the metal-insulator-metal waveguide structure on the optical transmission characteristics have been investigated using the finite-difference time-domain method. The result shows that, compared with the single straight waveguide, an obvious transmission peak appears in this structure. Moreover, the Fabry-Perot cavity is generated by the gap between the metal strip and the metal at the top surface of the waveguide when the length of metal strip is relatively large. The high order resonant mode is stimulated, the energy is resonated continuously in the Fabry-Perot cavity, and multiple resonance peaks of attenuation are generated. Meanwhile, a surface plasmon polariton bandpass filter based on embedded double metal strip is proposed. The transmission of this filter can be down to zero except the resonant peak. In addition, the resonant wavelength can be adjusted by changing the various parameters such as the length of the metal strip.