【作者】 崔海燕；

【导师】 侯蓝田；

【作者基本信息】 燕山大学 ， 电路与系统， 2010， 硕士

【摘要】 光子晶体光纤最引人注目的一个特点是可以具有很强非线性特性,很容易发生各种非线性效应,尤其是超连续谱的产生。本文设计出具有较高非线性的光子晶体光纤,并且利用多极法对有效模面积、非线性系数进行了研究;利用分步傅里叶方法求解广义非线性薛定谔方程,对设计的高非线性光子晶体光纤超连续谱的产生进行了研究,主要研究内容如下:首先,利用多极法对光子晶体光纤的有效模面积和非线性系数进行了数值模拟,分析发现,通过改变光子晶体光纤包层空气孔间距和空气孔直径,可以有效地调节非线性的大小。其次,利用分步傅里叶方法对广义非线性薛定谔方程进行了数值求解,数值模拟了超短脉冲在自行设计的具有较高非线性的光子晶体光纤中传输的情况,发现在光纤的不同色散区,初始啁啾系数C、脉冲的初始宽度T0、脉冲的峰值功率P0、脉冲的中心波长对脉冲的传输特性影响是不同的。要想获得最优的超连续谱,既要选择合适结构参数的光子晶体光纤,又要合理的选择输入脉冲的参数。然后,对本课题组自行拉制出的光子晶体光纤进行了实验研究,实验所选的光纤为外包层空气孔直径大小各异,但结构周期有序的单纤芯光子晶体光纤,并从两个方面对其产生的超连续谱进行了研究,一是泵浦功率不同,二是入射脉冲的中心波长不同。实验研究发现产生的超连续谱无论是光谱宽度,还是脉冲形状都不同。最后,对实验室仅有的多芯光子晶体光纤进行了实验研究,做出了比较好的超连续谱,光谱展宽范围都达到了2000 nm以上,此项研究,为不加任何非线性材料的仅依靠光子晶体光纤的结构产生范围更宽的超连续谱提供了一种新的研究方向。更多还原

【Abstract】 The most striking feature of photonic crystal fiber is highly nonlinear characteristic, it is prone to a variety of nonlinear effects, especially supercontinuum generation. In this text, I designed a photonic crystal fiber with high nonlinear, studied the effective area and nonlinear coefficient by multipole method. Supercontinuum generation of the photonic crystal fiber has been studied using split-step Fourier method for generalized nonlinear Schrodinger equation. The main contents are described as follows:First of all, numerical simulated the effective area and nonlinear coefficient of photonic crystal fiber using multipole method. The analysis shows that the size of nonlinear can be effectively regulated by changing the air hole pitch and air hole diameter of photonic crystal fiber.Secondly, numerical simulated the transmission of ultrashort pulses in self-designed highly nonlinear photonic crystal fiber, using split-step Fourier method for generalized nonlinear Schrodinger equation.It is found that the influence of initial durations T0, peak powers P0, initial chirp C and center wavelength on laser pulses evolution is different in PCF’different dispersion regions. If we want to obtain optimization supercontinuum,we not only choose the PCF with suit parameter but also choose fit pulse parameters.Then, I experimented the photonic crystal fiber which drawn by our group.The single core fiber which I choosed was different air hole diameter,but orderly structure.I studied the supercontinuum generation from two aspects, different pump power and center wavelength. It is found that not only spectral width but also pulse shapes different of supercontinuum generation.Finally, I experimented the only multi-core photonic crystal fiber.The spectral broadening scope over 2000 nm, this study provides a new research direction on wider range of supercontinuum without any non-linear material only rely on the structure of PCF.更多还原