【作者】 李立肖；

【导师】 侯蓝田；

【作者基本信息】 燕山大学 ， 光学工程， 2010， 硕士

【摘要】 光子晶体光纤中的色散特性和高非线性特性研究是当前光子晶体光纤研究的两个重要领域,而具有双零色散波长的光子晶体光纤的非线性特性研究已成为其研究的重点之一。本文从理论和实验上分别对光子晶体光纤的双零色散特性和非线性特性进行了研究,主要内容如下:首先,利用改进的有效折射率法对不同结构光子晶体光纤的色散和非线性系数进行了数值模拟,分析了结构参数对色散和非线性系数的影响,并在此基础上进一步研究了具有两个零色散波长的光子晶体光纤的双零色散和非线性特性,从而为具有双零色散波长的光子晶体光纤的非线性研究提供了理论基础。其次,运用多极法通过优化孔节距和包层空气孔半径设计了一种具有双零色散波长的高非线性光子晶体光纤,利用分步傅立叶方法数值模拟超短脉冲在其中传输的情况。发现经过传输,两个零色散波长之间的主要能量被转换至位于正常色散区的两边带峰处,多于99%的光能都被转移至两边平坦的带峰,且两边带峰受波长影响较大,但对脉冲能量和泵浦脉冲的啁啾不敏感,这就产生了高稳定性的谱带,具有广泛的应用前景。最后,利用自制的高非线性光子晶体光纤进行了飞秒激光脉冲传输实验,研究了在不同功率、不同输入波长下光子晶体光纤的频率转换现象。分析了输入激光脉冲的中心波长、输入功率分别对光纤产生的反斯托克斯波的中心波长、强度以及频率转换效率的影响。结果显示,输入脉冲的中心波长越接近零色散波长,转换效率越大,当输入脉冲中心波长为760 nm时,产生的反斯托克斯波的中心波长为465 nm,其强度是抽运波剩余强度的8.1倍,转换效率高达90%。更多还原

【Abstract】 The study of dispersion and nonlinearity of photonic crystal fibers are two important fields in the research of photonic crystal fibers. And the study of nonlinearity of photonic crystal fibers with two zero-dispersion is becoming the most important one of the research of photonic crystal fibers. The two zero-dispersion and nonlinear properties of photonic crystal fibers are investigated respectively. The main results are summarized as follows:Firstly, the dispersion and nonlinear coefficients of several different PCFs are numerical simulated by Improved Fully Vectorial Effective Index Method (IFVEIM). The relation between the structure parameters and dispersion, the structure parameters and nonlinear coefficient are analyzed. With the variety rule, the two zero-dispersion and nonlinearity of photonic crystal fibers with two zero-dispersion are investigated.Second, a kind of photonic crystal fiber with two zero-dispersion wavelengths is investigated in use of multipole method by tailoring the pitch and the diameter of cladding hole. The slip-step Fourier method is used to numerically simulate the ultrashort pulses’transmission in this fiber. As the result of transmission, the mostly energy between the two zero dispersion wavelength is transformed into the two spectral lobes. The efficiency of pumping is so high that more than 99% energy of input is transferred into the two spectral lobes. The two spectral lobes are very flat, they fluctuate with wavelength and insensitive to pulse energy as well as chirp of pump pulse, thus resulting in the high stability of spectra and making it have wide applications.The final, it is demonstrated that femtosecond pulses transmit in a highly nonlinear PCF manufactured by our group. The frequency conversion in abnormal dispersion region of a highly nonlinear PCF at the different power and wavelength are researched by Femtosecond Laser Pulses. Analyze the influence of central wavelength and power of input pulses on the output spectrum. When the central wavelength of input pulses is different, the frequency conversion follows the changes, which is bigger as the central wavelength of input pulse is more near to the zero-dispersion wavelength. Especially when central wavelength of input pulses is 760 nm, the central wavelength of anti-Stokes wave is 465 nm, the intensity of anti-Stokes is eight times more than the intensity of residual pump energy, and the transform-efficiency exceeds 90%.更多还原