高非线性石英光纤产生中红外超连续谱的研究
文献类型：学位论文
| 作者 | 高娟娟 |
| 学位类别 | 硕士 |
| 答辩日期 | 2015 |
| 授予单位 | 中国科学院上海光学精密机械研究所 |
| 导师 | 廖梅松 |
| 关键词 | 非线性 石英 光子晶体光纤 超连续谱 中红外 |
| 其他题名 | Studies of Mid-infrared Supercontinuum Generation in High Nonlinear Silica Fibers |
| 中文摘要 | 超连续谱的产生是指当大功率脉冲通过非线性介质时，由于自相位调制、交叉相位调制、受激拉曼散射和四波混频等非线性效应与光纤的群速度色散的共同作用而使脉冲频谱展宽的现象。中红外超连续谱由于在众多领域，例如：光谱学、定向红外对抗、医学诊断及生物医学等有重要应用而被广泛研究。 石英光纤因其在物理化学方面有软玻璃光纤所不具备的优势，成为产生超连续谱的重要介质。特别是石英玻璃具有很高的转变温度。因此，石英光纤能够承受大功率泵浦，从而产生高功率中红外超连续谱。研究利用石英光纤产生中红外超连续谱对中红外超连续谱功率的提高具有重要意义。 本文通过利用分步傅里叶方法求解包含石英光纤的材料损耗与波导损耗在内的非线性薛定谔方程，对利用石英光子晶体光纤产生中红外超连续谱进行研究。设计了具有不同色散特性的光子晶体光纤，利用有限元法求解得到光纤的色散、损耗及模场特性。为了得到宽带高效中红外超连续谱，考虑了光纤的非线性、泵浦脉冲波长、光纤长度对中红外超连续谱的影响。通过利用不同波长的泵浦脉冲泵浦具有不同色散特性的光子晶体光纤，研究飞秒和皮秒机制下超连续谱的产生。最终，在石英光纤中产生了中红外超连续谱，得到了可以在石英光纤中将超连续谱展宽到4 μm的方案。此外，本文还研究了超连续谱的转化率随脉冲传播距离变化的规律，在合适的光纤长度下，得到了高效宽带中红外超连续谱。中红外超连续谱光源的最大转化率达40.9 %。这里的转化率是指波长在2-4 μm的超连续谱的功率与输入光纤的脉冲总功率之比。最后，通过合理选择泵浦源，在保证光谱展宽到中红外的情况下，将孤子阶数降低到10以下，得到了高相干性中红外超连续谱。本文第一次系统地研究了利用石英光纤产生中红外超连续谱的方法，并研究了中红外超连续谱的长波限，转化率及相干性。 |
| 英文摘要 | Supercontinuum generation is a phenomenon that when a pulse with high power transmits in a nonlinear medium, the nonlinear effects such as Self Phase Modulation, Cross Phase Modulation, Stimulated Raman Scattering, Four Wave Mixing and Group Velocity Dispersion work together and make the spectra become broader. Mid-infrared supercontinuum has been widely studied because of its numbers of applications in many fields, such as: spectroscopy, directional infrared countermeasure, medical diagnosis, biomedicine and so on. Thanks to the intrinsic advantages of silica fiber in chemical and physics properties which soft glass does not have, silica fiber has been the important media of supercontinuum generation. Expecially, silica glass has a high transition temperature, which allows it to withstand high pumping power and thus generates supercontinuum with high power. The study of mid-infrared supercontinuum generation in silica fiber is of great significance for high power mid-infrared supercontinuum generation. This paper studies supercontinuum generation by solving nonlinear Schr?dinger equation which involves loss of silica fiber with split-step Fourier method. Photonic crystal fibers with different dispersion characteristics are designed and finite element method is used to calculate their dispersion, confinement loss and mode field characteristics. To generate broadband mid-infrared supercontinuum with high energy conversion efficiency, impacts of dispersion, nonlinearity, pumping wavelength and fiber length to suppercontinuum generation are taken into account. Supercontinuum generation under mechanism of femtosecond and picosecondis investigated by injecting pumpe pulses with different wavelengths into photonic crystal fiber with different dispersion characteristics. Mid-infrared supercontinuum is generated in silica fiber and the scheme of mid-infrared supercontinuum which is broadened to 4 μm is got, ultimately. It is achieved by studies of mid-infrared supercontinuum generation under femtosecond and picosecond mechanism in silica fibers which are pumped at different wavelengths. Besides that, variation of conversion efficiency with fiber length is investigated. Broad-band supercontinuum with high conversion efficiency is generated in fiber with appropriate length. The biggest conversion efficiency of mid-infrared supercontinuum light source reaches 40.9 %. Conversion efficiency refers to the ratio of supercontinuum power generated in 2-4 μm range to the total input power. At last, mid-infrared supercontinuum with high coherence is generated by optimizing pump pulse to keep the soliton order number less than 10. Mid-infrared supercontinuum generation in silica fiber is firstly reported and the long-wavelength egde, conversion efficiency and coherence of mid-infrared supercontinuum are investigated systematically, in this paper. |
| 语种 | 中文 |
| 源URL | [http://ir.siom.ac.cn/handle/181231/16916]  |
| 专题 | 上海光学精密机械研究所_学位论文 |
| 推荐引用方式 GB/T 7714 | 高娟娟. 高非线性石英光纤产生中红外超连续谱的研究[D]. 中国科学院上海光学精密机械研究所. 2015. |
入库方式： OAI收割
来源：上海光学精密机械研究所
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