Wang Yipei, Ma Yaoguang, Guo Xin, Tong Limin
Department of Physics and Institute of Nanoscience, National Chung Hsing University, Taichung 40227, Taiwan.
Opt Express. 2012 Aug 13;20(17):19006-15. doi: 10.1364/OE.20.019006.
Single-mode plasmonic waveguiding properties of metal nanowires with dielectric substrates are investigated using a finite-element method. Au and Ag are selected as plasmonic materials for nanowire waveguides with diameters down to 5-nm-level. Typical dielectric materials with relatively low to high refractive indices, including magnesium fluoride (MgF2), silica (SiO2), indium tin oxide (ITO) and titanium dioxide (TiO2), are used as supporting substrates. Basic waveguiding properties, including propagation constants, power distributions, effective mode areas, propagation distances and losses are obtained at the typical plasmonic resonance wavelength of 660 nm. Compared to that of a freestanding nanowire, the mode area of a substrate-supported nanowire could be much smaller while maintaining an acceptable propagation length. For example, the mode area and propagation length of a 100-nm-diameter Ag nanowire with a MgF2 substrate are about 0.004 μm2 and 3.4 μm, respectively. The dependences of waveguiding properties on geometric and material parameters of the nanowire-substrate system are also provided. Our results may provide valuable references for waveguiding dielectric-supported metal nanowires for practical applications.
采用有限元方法研究了具有电介质衬底的金属纳米线的单模等离子体波导特性。选择金和银作为直径低至5纳米级的纳米线波导的等离子体材料。典型的具有相对低到高折射率的电介质材料，包括氟化镁（MgF2）、二氧化硅（SiO2）、氧化铟锡（ITO）和二氧化钛（TiO2），被用作支撑衬底。在660纳米的典型等离子体共振波长下获得了包括传播常数、功率分布、有效模面积、传播距离和损耗在内的基本波导特性。与独立纳米线相比，衬底支撑的纳米线的模面积可以小得多，同时保持可接受的传播长度。例如，具有MgF2衬底的直径为100纳米的银纳米线的模面积和传播长度分别约为0.004μm2和3.4μm。还给出了波导特性对纳米线-衬底系统的几何和材料参数的依赖性。我们的结果可为实际应用中波导电介质支撑的金属纳米线提供有价值的参考。
