基于正常色散光纤产生超连续谱的研究

发布时间：2018-03-09 13:31

本文选题：光子晶体光纤　切入点：超连续谱　出处：《北京交通大学》2015年硕士论文　论文类型：学位论文

【摘要】：摘要：小芯径光子晶体光纤具有高非线性、无截止单模和可控的色散等特性,在产生超连续谱方面具有重要的研究价值。目前,在光子晶体光纤中泵浦超短脉冲产生超连续谱的研究分析,已经成为非线性光纤光学的一个重要分支。如何设计光子晶体光纤的几何结构,获得色散平坦变化的色散曲线,从而产生超宽带超连续的连续谱,是当前的研究热点之一。本文的主要工作是研究在正常色散光纤中泵浦超短脉冲产生超连续谱,具体工作如下：首先,为比较在光纤的正常色散区和反常色散区产生的SC,设计了零色散波长为1298nm的单模阶跃折射率光纤。理论分析泵浦中心波长分别处于光纤零色散波长附近的正常色散区和反常色散区条件下产生的超连续谱。数值结果显示在靠近零色散波长的反常色散区可以获得带宽为1418nm(20dB),平坦度为42dB的超连续谱。其次,为研究光子晶体光纤的色散特性与其结构参数的关系,分别使用了两种设计光子晶体光纤参数的方法：保持孔直径与孔间隔的比值不变,改变孔直径；保持孔间隔不变,改变孔直径与孔间隔的比值。通过数值计算,得到了全正常色散光子晶体光纤的几何结构。为研究在正常色散区飞秒脉冲泵浦光子晶体光纤产生超连续谱,设计了全正常色散光子晶体光纤。数值计算了在该光纤中飞秒脉冲泵浦产生的超连续谱,光谱的带宽为1131nm且平坦性较好。同时还研究了输入脉冲峰值功率、初始宽度对产生的超连续谱的影响。设计了一种部分空气孔填充液体材料的全正常色散光子晶体光纤,本文选取液体油作为材料,结果表明光纤在波长为1000-2000nm范围内色散曲线平坦变化。模拟了所设计的光子晶体光纤中超连续谱的产生,最终得到的超连续谱范围从918nm到2295nrn,并且整个在频谱范围内平坦性较好。
[Abstract]:Abstract: small core diameter photonic crystal fiber has the characteristics of high nonlinearity, no cut-off single mode and controllable dispersion, so it has important research value in the generation of supercontinuum spectrum. The study and analysis of the supercontinuum spectrum generated by pumped ultrashort pulses in photonic crystal fiber has become an important branch of nonlinear fiber optics. How to design the geometric structure of photonic crystal fiber and obtain the dispersion curve with flat dispersion variation. The main work of this paper is to pump ultrashort pulse in normal dispersive fiber to produce supercontinuum spectrum. The main work is as follows:. First, A single-mode step refractive index fiber with zero dispersion wavelength of 1298 nm was designed to compare SC-generated in the normal dispersion region and anomalous dispersion region. The normal color of the pump center wavelength near the zero dispersion wavelength of the fiber was theoretically analyzed. The numerical results show that in the anomalous dispersion region near the zero dispersion wavelength, the band width is 1418 nm ~ 2 dB and the flatness is 42 dB. Secondly, in order to study the relationship between the dispersion characteristics of photonic crystal fiber and its structural parameters, two methods of designing photonic crystal fiber parameters are used: to keep the ratio of hole diameter to hole spacing unchanged and to change the hole diameter; The geometric structure of the fully normal dispersive photonic crystal fiber is obtained by numerical calculation by changing the ratio of the hole diameter to the hole spacing by keeping the hole spacing unchanged. In order to study the generation of supercontinuum spectrum of photonic crystal fiber pumped by femtosecond pulse in normal dispersion region, a fully normal dispersive photonic crystal fiber is designed, and the supercontinuum spectrum generated by femtosecond pulse pumping in the fiber is numerically calculated. The bandwidth of the spectrum is 1131nm and the flatness is good. The influence of the input pulse peak power and the initial width on the supercontinuum spectrum is also studied. A fully normal dispersive photonic crystal fiber with partial air hole filled liquid material is designed. In this paper, liquid oil is selected as the material. The results show that the dispersion curve is flat in the wavelength range of 1000-2000nm. The generation of the supercontinuum spectrum in the designed photonic crystal fiber is simulated. The resulting supercontinuum spectrum ranges from 918nm to 2295nrn, and the flatness of the whole optical fiber is good in the spectrum range.
【学位授予单位】：北京交通大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TN253

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