光子晶体光纤填充和光子晶体光纤光栅的研究

【作者】 张春书；

【导师】 袁树忠；

【作者基本信息】 南开大学 ， 光学， 2006， 博士

【摘要】 本论文选题于国家973、863以及国家自然科学基金等项目,结合课题的要求和主要目标,在对光子晶体光纤(PCFs)传输特性研究的基础上,首先对光子晶体光纤光栅进行了理论和实验研究;然后,采用平面波展开法和有限单元法分析了在光纤的空气孔中填充高折射率液晶对光纤传导机制和传输特性的影响,提出并设计了几种新型光子晶体光纤;最后,提出并研制成功连续可调谐、输出功率谱均衡的全光纤化、高功率包层泵浦铒镱共掺光纤激光器实验样机。主要研究内容和成果包括以下基本方面:1、首次提出基于填充高折射率介质(液晶)的折射率引导型PCF的光子带隙理论分析方法,在此理论的指导下,采用平面波展开法和有限单元法研究了填充对光纤传导机制和传输特性的影响,研究结果表明液晶填充可以实现光子晶体光纤导光机制的转变。基于光子带隙理论利用光纤传导模式在带隙内外传导模式的损耗、色散等特性的差异,我们首次提出并设计了通过外界物理量调节包层中填充介质的折射率,改变光子带隙和传导模式的色散曲线的相对位置,从而改变传导模式的损耗和色散等特性,最终得到了可调谐光子带隙光纤。2、基于光子带隙理论首次理论研究了填充液晶对折射率传导型高双折射PCF传输特性的影响。分析了液晶填充对PCF的传导机制和传输特性的影响,并与光纤在填充前PCF的基本传导性质做了比较,研究结果表明液晶填充能够实现光纤传导机制的转变,同时得到更高的双折射。在此研究的基础上,首次提出并设计出通过用温度或者电磁场来调节空气孔中液晶的折射率来连续调节这种高双折射光子带隙光纤中的传输带隙和传导模式,最终实现的高双折射可调的光子带隙光纤。3、对光子晶体光纤光栅进行了理论和实验研究。利用紫外光写制的方法,成功地在柚子型PCF中写制了光纤Bragg光栅,在光栅的反射谱和透射谱中观测到了多个谐振波长,同时利用全矢量有限单元法分析了在柚子型PCF上写制的Bragg光栅的谐振特性,模拟结果和实验结果基本吻合。此外对柚子型PCF写制的Bragg光栅反射谱中多个峰的温度和应变传感特性进行了理论和实验研究。理论和实验研究结果均表明柚子型PCF Bragg光栅反射谱中的几个谐振峰更多还原

【Abstract】 This work is financially supported by the National Basic Research Program of China (973), the National 863 High Technology Project, and National Science Foundation projects. Based on the requirement and target of the projects, firstly, PCF Bragg grating are investigated theoretically and experimentally. Moreover, the effects of filling high refractive index material (nematic liquid crystal, NLC) in PCFs on the transmission mechanism and propagation properties are studied by using plane-wave method and finite-element method (FEM), farther, several novel PCFs are proposed and designed. Lastly, we propose and demonstrate a clad-pumped Er3+/Yb3+-codoped fiber laser, which integrate all performances of broad-band tunable wavelength, uniform output power spectrum, high repeat frequency and high average power to together. The details are described as follows:1. The photonic bandgap theory based on total internal reflection (TIR) PCFs filled with by high index material (NLC) is proposed for the first time. Based on this theory, the effects of NLC-filled TIR-PCFs on the transmission mechanism and propagation properties are studied using plane-wave method and full-vector FEM. The results indicate that the transformation of transmission mechanism can be achieved when the TIR-PCFs are filled with NLC. Moreover, utilizing the difference of characteristics of modes in the PBGs, we achieve the shifting of PBG and model dispersion by modulating the refractive index of filled material based on PBG theory. Further, tunable photonic bandgap fibers are proposed and demonstrated.2. The effects of filling NLC in the TIR-PCFs on propagation properties of high birefringent PCFs are firstly studied based on PBG theory. The influences of NLC-filling on transmission mechanism and propagation properties are researched in detail; moreover, we compare those results with the cases of non-filled PCFs. The results show that transformation of transmission mechanism and much higher birefringence can be achieved after NLC-filling. Farther, we firstly demonstrate the realization of modulating PBG and modes of PBG-PCFs by changing refractive index filled of filled NLC by virtue of temperature or electric field, and finally tunable更多还原