为了进一步明确MIM (Metal-insulator-metal)波导结构的SPP (Surface plasmon polariton)模式特性, 建立了MIM结构的SPP模式关系、激发系数和反射系数的理论模型。仿真数值计算结果表明: 较大的介质厚度的TM基态模式衰减超过了振荡模式衰减, 与传统的介质波导明显不同; TE模式表现为失真的介质光波导模式特性, 其传播距离要远大于TM0; MIM结构中腔的Q值随着长度增加而增大, 表明了SPP反射受限; 腔的品质因数改变与端面关系密切; MIM波导可以在具有更大Q值下确保光波更好地耦合成需要的SPP模式。

In order to further clarify SPP (surface plasmon polariton) mode feature in MIM(metal-insulator-metal)waveguide, we established the theoretical pattern of SPP model relationships in which excitation and reflection coefficients are obtained. A series of results have been derived from numerical simulation. TE mode is similar to dielectric waveguide with distortion, and its propagation distance is much larger than TM0. Q value in the cavity of MIM structure increases with the length, which indicates a limited reflection of SPP. The change of quality factor in the cavity has close connection with the end face. MIM waveguide ensures better coupling of light into the desired pattern SPP in the condition of greater Q value.