新型少模光纤波导特性分析及其器件的研制

发布时间：2017-12-28 09:13

  本文关键词：新型少模光纤波导特性分析及其器件的研制　出处：《北京交通大学》2016年博士论文　论文类型：学位论文

  更多相关文章： 少模光纤 光纤器件 大模场面积 单偏振 光纤激光器

【摘要】：新型大模场面积少模光纤(few-mode fiber, FMF)对下一代高速大容量无阻塞光通信系统、光纤传感技术与光纤激光器的研究具有十分重要的价值。模分复用系统充分利用FMF中多个正交模式作为独立信道和大模场面积等优势,大大提升光纤通信系统的通信容量,有效地解决光纤非线性效应引起的通信容量瓶颈问题,为下一代光纤通信系统提供重要保障。本论文主要针对多芯层少模光纤(multilayer-core FMF, MC-FMF)开展理论与实验研究工作。重点研究MC-FMF的结构设计与制作,并将MC-FMF应用于新型光纤器件的实现。在理论分析与应用研究过程中,深入认识了光纤结构参数与其特性之间的本质关系。大部分工作均处于该领域研究的前沿。本文主要取得的创新研究成果如下：1.提出并设计制作了一种新型MC-FMF,指出了光纤结构参数对波导特性影响的规律。通过光纤结构参数的优化调整,实现了波导中模式数量的控制,以及大模场面积与低弯曲损耗等良好性能的集成。建立了四芯层结构FMF的数学模型,采用数值方法计算了光纤特征参数。采用MCVD工艺实验制作了大模场面积低弯曲损耗的双模光纤(dual-mode fiber, DMF)样本。该DMF的基模模场面积可达280μm2,是普通单模光纤的四倍；在4.5cm弯曲半径条件下,光纤损耗可低至0.42dB/turn。建立了光纤准直器几何冗余度同尾纤模场面积之间关系的数学模型。利用多芯层结构光纤(multilayer-core fiber, MCF)的大模场面积特性,首次制作了基于MCF的光纤准直器。与普通单模光纤准直器相比其偏角冗余值提升了20%,降低了准直器用于空间光耦合的难度。2.提出并设计制作了一种严格双模的多椭圆芯层光纤(elliptical multilayer-core fiber, EMCF),指出了EMCF结构参数对双折射、非线性等特征参量影响的规律,发现了EMCF具有明显的偏振保持特性。针对弯曲状态下的非圆对称结构光纤,建立了EMCF折射率分布与传输损耗的计算模型。模型充分考虑了光纤结构对折射率分布的影响以及与光纤弯曲损耗相关的因素,从本质上揭示了EMCF在弯曲方向上产生弯曲损耗差异性的原因,表明该光纤具有各向异性的弯曲特性。实际制作出严格双模的EMCF样本,在适当弯曲半径与方向下,EMCF的基模中两偏振分量的弯曲损耗曲线发生走离,实现了单一偏振的低损耗传输。3.提出并研制了一种基于FMF的模式干涉器件。基于模式耦合理论,揭示了该光纤器件中的模式耦合过程。提出了两段非圆对称结构EMCF的熔接方案,使用EMCF实际制作了全光纤的马赫增德尔干涉仪(Mach-Zehnder interferometer, MZI)与迈克尔逊干涉仪(Michelson interferometer, MI)。在对基于FMF干涉器件传感原理的充分认识和理解的基础上,提出了应力与液位两参量传感的仿真方法。实际搭建了基于FMF的温度、应力、折射率、液位等物理量的传感系统,实现了其传感功能。提出并搭建了基于FMF的激光传感系统,显著提升了传感系统的分辨率。制作了一种以FMF-MI为滤波器的环型腔激光器,并用FMF-MI作为传感头实现了液位传感测量。液位的变化可调谐激光器输出波长。激光传感系统的输出激光消光比达到了43dB,远大于FMF-MI滤波器输出光谱的消光比：3dB带宽约为0.05nm,远小于滤波器输出光谱的3dB带宽,显著提升了液位传感的分辨率；实验测得该传感系统的液位传感灵敏度约为50.6pm/mm。4.提出并制作了一种少模布拉格光纤光栅(few-mode fiber Bragg grating, FM-FBG)。该FM-FBG的光纤载体仅支持LPo0与LP11两个模式场的传输,因此其反射和透射光谱中同时存在模式自耦合峰和模式场间互耦合峰。利用耦合模方程建立了该光栅的解析模型,揭示了FM-FBG的模式耦合过程,为进一步研究与求解FM-FBG特征参量提供了理论基础。通过仿真计算,找出了FMF中模式能量比、模式折射率差与耦合系数等参数分别对FM-FBG中谐振点强度、带宽、波长间隔等特性影响的规律。实际制作了基于FM-FBG的双波长可调谐激光器,利用EDF的光谱烧孔(SHB)效应,方便地实现了激光器单波长与双波长状态的转换。利用FM-FBG中LP01自耦合透射峰和LP01与LPn互耦合透射峰的滤波特性,在线型腔结构中实现了稳定的单横模输出(基模LP01)和LP01与LP11混合的多横模激光输出。
[Abstract]:The new large mode area few-mode fiber (FMF) is of great value for the next generation of high-speed and high-capacity non blocking optical communication system, optical fiber sensing technology and fiber laser. Make full use of multiple orthogonal FMF model as an independent channel and large mode area advantages in mode division multiplexing system, greatly enhance the communication capacity of optical communication system, effectively solve the bottleneck problem of communication capacity caused by the nonlinear effect of optical fiber, provide an important guarantee for the next generation of optical fiber communication system. This thesis focuses on the theoretical and Experimental Research on multilayer-core FMF (MC-FMF) with multi core layer. The structure design and production of MC-FMF are emphatically studied, and MC-FMF is applied to the realization of the new optical fiber device. In the process of theoretical analysis and application, the essential relationship between the parameters of optical fiber structure and its characteristics is deeply understood. Most of the work is at the forefront of the research in this field. The main achievements of this paper are as follows: 1. a new MC-FMF is proposed and designed, and the influence of fiber structure parameters on waveguide characteristics is pointed out. Through the optimization and adjustment of the optical fiber structure parameters, the control of the mode number in the waveguide and the integration of the good performance of the large mode field area and low bending loss are realized. The mathematical model of the four core layer structure FMF is set up, and the characteristic parameters of the fiber are calculated by numerical method. A double mode fiber (dual-mode fiber, DMF) sample of large mode field area with low bending loss was made by MCVD process. The base mode field area of the DMF can reach 280 mu m2, which is four times of the ordinary single mode fiber, and the fiber loss can be as low as 0.42dB/turn under the 4.5cm bending radius. The establishment of mathematical model of the relationship between fiber collimator geometric redundancy with the fiber mode field area. The optical fiber collimator based on MCF is made for the first time using the large mode field area characteristics of multilayer-core fiber (MCF). Compared with the ordinary single mode fiber collimator, the redundancy of the deflection angle of the collimator is increased by 20%, which reduces the difficulty of the collimator for the spatial light coupling. 2., we propose and design a strict double mode elliptical multilayer-core fiber (EMCF). We point out the influence of EMCF's structural parameters on birefringence and nonlinearity. We find that EMCF has obvious polarization maintaining property. The calculation model of the refractive index distribution and transmission loss of EMCF is established for the non circular symmetric structural fiber under the condition of bending. Considering the influence of fiber structure on the refractive index distribution and the factors related to the bending loss of optical fibers, the model reveals the reason of the difference in bending loss of EMCF in bending direction, which indicates that the fiber has anisotropic bending properties. Actually, a strict dual-mode EMCF sample is made, and the bending loss curve of the two polarization component is removed in the basic mode of EMCF under the proper bending radius and direction, and a single polarization low loss transmission is realized. 3. a model interferometer based on FMF is proposed and developed. Based on the mode coupling theory, the mode coupling process in the optical fiber device is revealed. A scheme of EMCF fusion is presented for two non-circular symmetric structures. The EMCF Mach-Zehnder interferometer (Mach-Zehnder interferometer MZI) and Michelson interferometer (Michelson interferometer MI) are fabricated by EMCF. On the basis of full understanding and understanding of the sensing principle based on FMF interferometer, a simulation method of stress and liquid level two parameter sensing is proposed. The sensing system based on the physical quantity of temperature, stress, refractive index, liquid level and so on, which is based on FMF, has been built, and its sensing function is realized. A laser sensing system based on FMF has been proposed and built, which greatly improves the resolution of the sensing system. A ring cavity laser with FMF-MI as the filter is made, and the liquid level sensing measurement is realized by using FMF-MI as the sensor head. The change of the liquid level can be tuned to the output wavelength of the laser. The laser sensor system output laser extinction ratio reached 43dB, far greater than FMF-MI the output spectrum of the filter extinction ratio: 3dB bandwidth is about 0.05nm, far less than the output spectrum of the filter bandwidth of 3dB, significantly enhance the resolution of liquid level sensing; measured the sensing system experimental position sensing sensitivity is about 50.6pm/mm. 4. a small mode Prague fiber Bragg grating (few-mode fiber Bragg grating, FM-FBG) is proposed and produced. The fiber carrier of FM-FBG only supports the transmission of two mode fields of LPo0 and LP11. Therefore, there is a pattern of self coupling peak and mode field mutual coupling peak in reflection and transmission spectra. The coupled mode equation is used to establish the analytical model of the grating and reveal the mode coupling process of FM-FBG, which provides a theoretical basis for further research and solving FM-FBG characteristic parameters. The influence of mode energy ratio, mode refractive index difference and coupling coefficient on the characteristics of resonant point intensity, bandwidth and wavelength interval in FM-FBG is found by simulation calculation in FMF. A dual wavelength tunable laser based on FM-FBG has been fabricated, and the spectral and hole burning (SHB) effect of EDF has been applied to realize the conversion of single wavelength to double wavelength. By using the filtering characteristic of LP01 self coupling transmission peak and the mutual transmission peak of LP01 and LPn in FM-FBG, the stable multitransverse mode output of single transverse mode output (base mode LP01) and LP01 and LP11 mixed mode are achieved in the online cavity structure.
【学位授予单位】：北京交通大学
【学位级别】：博士
【学位授予年份】：2016
【分类号】：TN253
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本文编号：1345433