条形介质加载型表面等离子体波导传输特性的研究

Study on the propagation chracteristics of strip dielectric loaded plasmonic waveguide

采用二维时域有限差分(FDTD)法,分析对比了介质-金属(IM)结构和金属-介质-金属(MIM)结构波导对光波传输特性的影响,以及通过对IM结构的尺寸、折射率进行优化得到最佳传输长度。数值结果表明,IM结构波导能使光波传输距离更长。对IM波导结构研究发现,当介质层厚为300nm,金属层厚为200nm时,传输效果最佳。基于这个参数的IM结构,计算介质层折射率对IM波导光传输特性的影响发现,介质层折射率为1.5时,在模场约束较好的情况下,传输损耗降低,表面等离子体波的传输长度最长。整体优化后的条型波导可以实现最大传输距离为37μm。这一设计和优化波导结构参数的方法不仅拓宽了介质加载型表面等离子体激元(SPP)波导结构的理论基础,在纳米光学集成器件研究上也具有一定的应用潜能。

The effect on light transmission characteristics of the dielectric-metal （IM） structure and met- al-insulator-metal （M/M） waveguides was compared and analyzed using two-dimensional finite difference time domain（FDTD）method in this paper. The optimal propagation length can be obtained after optimi-zing of structure size and refractive index of IM structure. The numerical results indicate that the propa- gation length of surface plasma waveguides with IM structure is longer than that with MIM structure. We also found that the best propagation result of the IM structure waveguide can be achieved when the medium thickness is 300 nm and the thickness of the metal layer is 200 nm. Based on those parameters, we calculate the effect of refractive index of the dielectric layer, on the optical transmission characteristics of IM waveguide. We find that the propagation length of surface plasma waveguide is longest when refractive index is 1.5. The design and optimization of waveguide structure parameters not only broaden the theoretical basis of the dielectric loaded surface plasmon waveguide structure, but also have potential applications in the research of nano optical integrated devices.