基于SPPs-CDEW混合模式的亚波长单缝多凹槽结构全光二极管

发布时间：2018-11-20 06:32

【摘要】：全光二极管是集成光子回路上最基本的光子器件,如何有效增强全光二极管的单向透射性,提高消光比一直是学者们研究的重点.当前,利用表面等离极化激元(surface plasmon polaritons,SPPs)和复合衍射衰逝波(composite diffracted evanescent wave,CDEW)的亚波长金属微纳结构构建全光二极管器件还鲜有研究.因此,开发出一种可调制的全光二极管,对未来制备复杂的光子回路具有重要意义.本文提出了一种基于SPPs-CDEW混合模式设计全光二极管的方法和结构,该结构结合纳米缝中的类法布里-珀罗共振效应,利用结构参数对SPPs进行调控,实现了光束单向透过的功能.首先,利用理论推导和有限元算法分析了单缝-对称双凹槽纳米结构的透射增强现象,提出了透射增强和削弱的物理机理.其次,计算出规约化透射率随单狭缝和凹槽对之间距离变化的远场透射谱,给出的理论和数值计算结果符合得很好.最后,通过此透射谱精确确定凹槽的位置和数量,得出上表面对称分布五对增强透射凹槽、下表面六对抑制透射凹槽的最优全光二极管结构,有效增强了全光二极管的单向透射性,提高了消光比,最大消光比可以达到38.3 dB,即正向透射率是反向透射率的6761倍,比已有文献提高了14.6 dB,并在850 nm左右有70 nm宽的工作波长带宽(20 dB).本文提出的光二极管结构简单,宽带宽工作,易于集成,耦合效率高,研究结果对光学信号传输、集成光回路、超分辨率光刻等相关领域具有潜在的应用价值.
[Abstract]:All-optical diodes are the most basic photonic devices in integrated photonic circuits. How to effectively enhance the one-way transmission of all-optical diodes and improve extinction ratio has been the focus of scholars. At present, there are few studies on the fabrication of all-photodiode devices with subwavelength metal microstructures using (surface plasmon polaritons,SPPs) and (composite diffracted evanescent wave,CDEW). Therefore, the development of a modulable all-light diode is of great significance for the fabrication of complex photonic circuits in the future. In this paper, a design method and structure of all-light diodes based on SPPs-CDEW hybrid mode is proposed. The structure combines Fabry-Perot resonance effect in nano-cracks and uses structural parameters to regulate SPPs. The function of unidirectional beam transmission is realized. Firstly, the transmission enhancement of single-slit symmetric double-groove nanostructures is analyzed by theoretical derivation and finite element method, and the physical mechanism of transmission enhancement and weakening is proposed. Secondly, the far-field transmission spectrum with the variation of the distance between single slit and groove pair is calculated, and the theoretical and numerical results are in good agreement. Finally, the position and quantity of the grooves are determined accurately by the transmission spectrum. Five pairs of enhanced transmission grooves on the upper surface and six pairs on the lower surface are obtained. The unidirectional transmittance of all-light diodes is effectively enhanced, and the extinction ratio is increased. The maximum extinction ratio can reach 38.3 dB, that is, the forward transmittance is 6761 times of the reverse transmittance, which is 14.6 dB, higher than the previous literature. And working wavelength bandwidth of about 70 nm wide (20 dB).) at 850 nm The proposed photodiode has the advantages of simple structure, wide bandwidth, easy integration and high coupling efficiency. The research results have potential application value in optical signal transmission, integrated optical circuit, super-resolution lithography and other related fields.
【作者单位】：西北师范大学物理与电子工程学院;兰州理工大学理学院;
【基金】：国家自然科学基金(批准号:61367005,41461078)资助的课题~~
【分类号】：TN31

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