基于片上布里渊效应全光模式转换的机理研究

发布时间：2017-12-31 18:44

本文关键词：基于片上布里渊效应全光模式转换的机理研究　出处：《华中科技大学》2016年博士论文　论文类型：学位论文

【摘要】：为了提升光纤通信系统的通信容量来应对不断增加的通信业务需求,目前的高速光通信系统中已经利用了单模光纤中光波包括幅度、频率、相位以及偏振态等自由度。因此在面对未来对通信容量进一步增加的情况下,就需要开发光纤通信系统中新的复用自由度来提升光纤通信容量。借鉴偏振复用(PMD)中对两种相互正交的偏振态的复用技术,在少模光纤中利用空间模式正交特性构成的模分复用(mode-division multiplexing:MDM)技术,可以为光纤通信系统提供了一个崭新的复用自由度从而进一步的实现光纤通信容量的倍增。因此,MDM技术被广泛的认为是下一代光纤通信系统的重要潜在技术。MDM技术对于满足迅猛增长的通信业务的需求,具有重要的理论与实际意义。模式转换技术是构建灵活且与现有光通信网络相兼容的模分复用传输系统的关键技术。随着现有光学器件向着可集成化方向的发展,一个可集成、宽工作带宽且可调谐的光模式转换器将会在未来的MDM系统中发挥重要的作用。在国家自然科学基金的资助下,本论文对硅基波导中基于前向受激布里渊效应和声光效应的模式转换器进行了一系列的理论研究以及制作测试。概括本论文的研究成果与贡献可以总结为如下几个方面:(1)通过深入了解和分析传统的受激布里渊效应,在同时考虑光辐射压力和电致伸缩力的情况下推导出了布里渊效应中的声光耦合方程。然后从原理和理论上论证了前向布里渊效应可以用于实现全光模式转换。另外,根据多模光波导中布里渊效应激发产生的声场与光场的相位匹配条件确定了在模式转换过程中声场的传播方向及其存在形式。(2)通过对布里渊效应中声光相互作用及其耦合波方程的分析,得到了在微纳尺度的硅基芯片上实现高效的布里渊效应的基本条件。即能同时将声场和光场限制在同一个区域以较低的损耗进行传播,并且声场和光场的色散特性需要可以通过波导中不同的结构参数进行单独控制。为了实现这两个条件,我们提出了由悬空的矩形光波导和声子晶体组成混合波导结构的方案。(3)通过对材料特性的综合分析,选择了硅(Si)和氮化硅(Si3N4)分别作为光波导和声子晶体的组成材料。在设计过程中通过将矩形Si波导作为线缺陷埋入了Si3N4的声子晶体平板中从而形成了声光混合波导,从而将声场和光场限制在了波导的同一个区域内。然后通过数值仿真,分析了常用的三种不同声子晶格类型(四方晶格,六方晶格和蜂巢状晶格)及其相关结构参数对混合波导中声场特性的影响。并根据对仿真结果的分析,给出了三种不同的声子晶体结构中的最佳结构参数。最后通过对不同声子晶体结构在最优化参数下的性能的横向对比,得出蜂巢状的晶格结构是此处声子晶体的最佳方案。(4)提出了一种基于声光混合波导中前向受激布里渊的全光模式转换器,并且给出了波导的最佳结构参数。然后通过数值仿真分析给出了由光场基模11xE向高阶模式21xE转换的数值过程。仿真结果表明,该模式转换效率将会受到波导长度和注入光功率强度的影响。并且在考虑声场和光场损耗的情况下,该波导能够在通信波段中较大的带宽范围内实现最高88%的模式转换效率。(5)提出了一种基于动态光栅的可逆并且可调谐光模式转器的设计方案,并且推导出了声光相互作用的声光耦合波方程。在综合考虑声场和光场限制和色散曲线特性的情况下给出了一个能实现三种模式转换的声光混合波导的最优化参数。另外,通过仿真分析可知在给定波导长度的情况下,该模式转换器的转换效率可以通过控制注入声场的强度来调节。并通过分析其相位匹配条件得出可以通过调节注入声场频率实现多种不同模式转换的方法。然后分析了在给定声场频率下,该模式转换器对于每种模式转换的工作带宽。最后,根据理论分析可知,通过优化该波导结构还能实现更多种类的光模式转换,这将使得该器件在未来的MDM系统中有着广泛的使用前景。(6)利用微纳工艺平台制作出了声光混合波导样片,并通过对样片波导的测试论证了我们设计的混合波导中前向布里渊效应的存在。
[Abstract]:In order to enhance the communication capacity of optical fiber communication system to cope with the increasing traffic demand, high speed optical communication system in the current using single-mode fiber wave including amplitude, frequency, phase and polarization degree of freedom. So in the face of the future to further increase of communication capacity, requires the development of optical fiber communication system a new degree of freedom to improve the multiplexing capacity of optical fiber communication. Using polarization division multiplexing (PMD) of the two orthogonal polarization multiplexing technology, using orthogonal characteristics of spatial pattern in few mode fiber in mode division multiplexing (mode-division multiplexing:MDM) technology, can provide a new degree of freedom multiplexing to further the capacity of optical fiber communication doubling optical fiber communication system. Therefore, MDM technology is widely considered to be an important potential next generation fiber-optic communication system in.MD The demand of M technology for communication services meet the rapid growth, has important theoretical and practical significance. The mode conversion is a key technology to build flexible and compatible with the existing optical communication network mode division multiplexing transmission system. With the development of the existing optical devices can be integrated to the direction of an integrated optical mode converter wide bandwidth tunable and will play an important role in the MDM system in the future. In the National Natural Science Fund, this paper on the silicon waveguide mode converter based on the stimulated Brillouin scattering effect and carried out a series of theoretical research and making contributions of testing. Summary of this thesis can be summarized as follows: (1) through in-depth understanding and analysis of the SBS tradition, while considering the radiation pressure and electrostrictive force The case is derived in the acousto-optic coupling equation of Brillouin effect. Then the principle and theoretical arguments of the forward Brillouin effect can be used to realize optical mode conversion. In addition, according to the phase field and light Brillouin effect of multimode optical waveguide excitation field generated by the matching conditions to determine the direction of propagation in the sound field in the mode conversion process and form. (2) through the analysis of the effect of Brillouin acoustooptic interaction and coupling wave equation, the basic conditions of realizing efficient Brillouin effect on silicon chip micro nano scale on which can at the same time. The sound and light field limits in the same region to the low loss transmission and the sound and light field dispersion through the waveguide structure parameters need to be different for individual control. In order to achieve these two conditions, we propose a rectangular light hanging Guide and phononic crystals composed of hybrid waveguide structure. (3) through a comprehensive analysis of the material properties, the silicon (Si) and silicon nitride (Si3N4) were used as the materials of optical waveguide and photonic crystal. In the design process through the rectangular waveguide as Si line defect embedded in phononic crystal plate Si3N4 in order to form a sound mixed waveguide, which will sound and light field is limited in the same area within the waveguide. Then through numerical simulation, analyzed three different lattice types commonly used (square lattice, six square lattice and honeycomb lattices) influence parameters and structure of the sound field characteristics in hybrid waveguide. According to the analysis of the simulation results, the optimal structure parameters of three kinds of phononic crystal structure in different. Finally through comparing the performance of different phononic crystal structure in the optimum under the draw bee The lattice structure is the best solution to the nested phononic crystal. (4) proposed a hybrid waveguide based on acousto-optic forward optical mode converter stimulated Brillouin, and gives the optimal structure parameters of waveguide. Then through numerical simulation analysis presented the numerical conversion process by the light field based 11xE mode to high order mode 21xE. The simulation results show that the mode conversion efficiency will be affected by the waveguide length and intensity of the incident light power. And in consideration of the sound field and the light field loss, the waveguide mode conversion can achieve up to 88% efficiency larger bandwidth range in the communication band. (5) proposed a and design of optical mode converter based on reversible dynamic tuning of the grating, and deduced the acoustooptic acoustooptic interaction of coupled wave equations. In consideration of the sound field and optical confinement and dispersion curve characteristics. Under the condition of a given parameter can be three mode conversion of acousto-optic waveguide hybrid optimization. In addition, through simulation analysis on a given waveguide length, the mode converter conversion efficiency can be adjusted by controlling the injection field strength. And through the analysis of the phase matching condition that can be realized by adjusting the conversion method a variety of different models. And then analyzes the injection frequency of sound field in a given field frequency, the mode converter for converting the bandwidth of each mode. Finally, according to the theoretical analysis, through the optical mode conversion optimization of the waveguide structure can achieve more types, which will make the device has a wide application prospect in MDM system in the future. (6) using micro nano technology platform produced acousto optic hybrid waveguide sample, and through the waveguide sample testing demonstrated our design The existence of the forward Brillouin effect in a hybrid waveguide.

【学位授予单位】：华中科技大学
【学位级别】：博士
【学位授予年份】：2016
【分类号】：TN929.11

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