【作者】 许鸥；

【导师】 简水生；

【作者基本信息】 北京交通大学 ， 通信与信息系统， 2009， 博士

【摘要】 光纤光栅是光纤技术中一种非常重要的基本器件,在光纤通信、传感等相关领域具有广阔的应用前景。本论文结合国家自然基金及国家863计划项目,针对基于光纤光栅的几种相关器件进行了深入的理论和实验研究,主要对光纤激光器及滤波器进行了结构设计与优化,并对倾斜光纤光栅进行了详细分析,获得的主要创新成果如下:1.提出了一种基于光纤光栅的双腔Fabry-Perot全光纤结构,给出了能够在光栅中心波长处实现单模运转的腔结构设计原则,并讨论了制作过程中腔长及光栅折射率调制量为非理想精度或存在误差时对结构性能产生的影响,为单频短线腔光纤激光器或环腔激光器中窄带选频器件的设计提供理论依据。2.提出并实验制作了一种将三个光纤光栅直接写入一段光敏掺铒光纤中构成的线腔光纤激光器结构,这种一体化结构在谐振腔内不存在焊接点,实验测量其实现了线宽小于5kHz的单纵模激光输出。3.提出并实际制作了一种可开关双波长掺铒光纤激光器结构,谐振腔由保偏光纤Sagnac环镜与两不同波长光纤光栅构成,实验中通过调节偏振控制器已实现任意单波长或同时双波长激光出射。4.提出了一种基于多个均匀光纤光栅的全光纤型多腔结构滤波器,旨在改善单腔结构滤波效果,对其透射特性进行了详细理论分析与数值计算,得出结论:为了提高谐振峰过渡带滚降特性,需要增加结构中光纤光栅的反射率,应用于不同情况时,可以通过调节腔长来得到所需的透射谐振峰带宽。对比四腔结构与两腔及单腔结构谐振透射峰,进一步说明了多腔结构对滤波性能的改善。5.基于利用耦合模理论分析倾斜光纤光栅的方法,建立了反射型均匀周期倾斜光纤光栅简化计算模型,推导出了包括波长依赖反射率、最大反射率、峰值反射波长、传输损耗系数在内的谱参数一般表达式。其中传输损耗系数表达式在其他文献中并未有所报道。在理论分析的基础上,分别数值计算了反射谱与传输损耗谱,研究了倾斜角度、光栅长度、折射率调制幅度、入射光偏振态对光栅谱特性的影响,并给出了定性的解释。6.基于耦合模式理论及Mueller矩阵法,首次定量地分析倾斜光纤光栅的偏振特性,推导出明确的倾斜光纤光栅波长相关偏振依赖损耗表达式,通过模拟计算相应的偏振依赖损耗,比较了不同倾斜角度光纤光栅的偏振能力。更多还原

【Abstract】 The fiber phase grating is an important candidate in fiber technology,and has found many useful applications in fiber communication and fiber sensing.Under the supports of national 863 high technology program and national nature science foundation,this thesis is devoted to the detailed theoretical and experimental researches on fiber gratings and fiber grating based devices,mainly including proposing and optimizing the structures of fiber lasers and filters,deeply investigating the characteristics of tilted fiber gratings.And the main achievements of this thesis are listed as follows:1.A novel all fiber two-cavity Fabry-Perot configuration based on fiber Bragg gratings is proposed.The design guidelines of the cavity structure are presented to realize the single mode operation at the center wavelength of the fiber grating.The fabrication error tolerances of the structures,including inaccurate cavity lengths and index modulations of fiber gratings,are calculated and discussed,providing the principles for the design of short linear-cavity fiber laser and narrow-band filters in ring cavity fiber laser.2.A single-longitudinal-mode erbium-doped linear-type fiber laser is proposed and experimentally realized,which consists of three fiber Bragg gratings directly written in a piece of photosensitive erbium-doped fiber.The laser has no intra-cavity fusion splices,and the linewidth of less than 5-kHz is acquired.3.A switchable dual-wavelength erbium-doped fiber laser is proposed and experimentally demonstrated,which is constructed by a polarization-maintaining fiber Sagnac loop mirror and two fiber gratings with different wavelengths. Wavelength switching operation was achieved by properly adjusting the polarization controller in the polarization-maintaining fiber Sagnac loop mirror. Stable single- or dual-wavelength lasing output can be realized.4.An all fiber multi-cavity configuration based on fiber Bragg gratings is proposed and used as a filter,in order to improve the filtering performance of the single-cavity structures such as flatness of the top and steepness at the edge of transmission peak.The characteristics of the transmission spectra for the configuration are analyzed and modeled in detail.The results show that the steepness of the peak slope can be improved by increase of fiber grating reflectivites,and required band-width of the peak can be obtained by adjusting the cavity lengths in different applications.The comparison of the transmission peaks of four-cavity,two-cavity,and single-cavity structures demonstrates the improved performance of filters.5.A simplified model for refective tilted fiber gratings of uniform periods is presented to investigate the spectral characteristics,on the basis of the coupled-mode theory.Explicit expressions are derived for the spectral parameters of reflection and transmission loss spectra,including wavelength related reflectivity, maximum reflectivity,peak-reflection wavelength and transmission loss,among which the expression of transmission loss is derived for the first time.Numerical simulations are carried on to show the dependences of grating spectral responses on the structural parameters,such as tilt angle,grating length,index modulation amplitude and polarization states,and qualitative explanations of the spectral behaviors are presented.6.Based on the coupled-mode theory and Mueller matrix method,the polarization properties of tilted fiber gratings are analyzed quantitatively for the first time.The explicit expression of wavelength-dependent polarization-dependent loss for tilted fiber gratings is derived.The polarization capability of tilted fiber gratings with different tilt angles are compared by simulating the corresponding polarization-dependent loss.更多还原