基于表面等离子体波的硅基集成非线性光波导设计
时间:2018-12-04 19:58 来源:毕业论文 作者:毕业论文 点击:次
| 摘要随着人们对信息的带宽、容量和信息处理速度等的要求不断提高，基于全光网络的全光信号处理将成为未来信息领域发展的一大趋势，而非线性器件是全光网络中非常重要的组件。等离子体波具有高度局域性，将其与硅基波导相结合设计新型等离子体波导能显著提高金属介质表面的光强密度，进而可提升波导的非线性性能。通过对表面等离子体理论和非线性效应的研究，设计了银-聚合物-硅-二氧化硅衬底的等离子体波导结构，光场主要束缚在银和聚合物的界面处，非线性系数达到了4 1 110 Wm ；和介质波导相比，该等离子体波导的非线性系数提高到 74.7 倍；通过优化波导尺寸，发现当波导宽度和高度分别为 212.5nm 和 262nm 时，由非线性系数和传播长度乘积定义的品质因数取得最大值；利用优化后的波导结构，观察到非线性系数和传播长度在很大的波长范围内均保持着较大的数值。等离子体硅基波导非线性系数和传播长度均较大且对波导尺寸及波长不敏感等特性，有利于非线性现象的发生。采用拉锥光纤石墨烯复合波导结构作为实验用的等离子体波导，和未加石墨的拉锥光纤相比，复合波导的基于四波混频的波长转换效率得到了明显的提升；研究还表明，两光源波长相隔较近、光源功率越大，则转换效率越高。 31135 毕业论文关键词 表面等离子体波 硅基波导 非线性系数 传播长度 品质因数 Title The design of nonlinear optical silicon-integrated waveguide based on surface plasmon wave Abstract With the increasing requirements of information bandwidth, capacity and information processing speed, etc., all-optical networks based on all optical signal processing will become a major trend in the near future and nonlinear devices are very important components in all-optical networks. Surface plasmon wave is highly localized to the interface of metal and dielectric, if combined with silicon waveguide to design novel plasma waveguide, we can significantly improve intensity density of the metal-medium interface and enhance the nonlinear properties of the waveguide furthermore. Silver-polymer- silicon - silica substrate structure plasma waveguide is designed with the study of surface plasmon theory and nonlinear effects. Light field is mainly bound in the interface between silver and polymer layer. The nonlinear coefficient reaches4 1 110 Wm of the plasma waveguide and is 74.7 times of the dielectric waveguide. By optimizing the plasma waveguide dimensions, it can be found that when the width and height takes 212.5nm and 262nm respectively, the figure of merit defined by the product nonlinear coefficient and propagation length has maximum value. Using the optimized waveguide structure, it can be observed that the nonlinear coefficient and propagation length are both maintained in large numbers in a large wavelength range. Both the nonlinear coefficient and propagation length are large and their insensitive to the waveguide dimensions and wavelength of plasma silicon waveguide are benefit to the occurrence of nonlinear phenomenon. Taking the composite waveguide of tapered fiber and graphene as the plasma waveguide for experimentand the waveguide of tapered fiber only for contrast, Composite waveguide experiences more significant wavelength conversion efficiency based on four wave mixing than the contrast. Studies have also shown that the conversion efficiency becomes higher when the two wavelength becomes nearer and the power becomes lager of the two optical sources. (责任编辑：qin) |