【作者】 郝蕴琦；

【导师】 王政平；

【作者基本信息】 哈尔滨工程大学 ， 光学， 2007， 硕士

【摘要】 2×2单模光纤耦合器是一种重要的光纤无源器件，广泛应用于通信、相干光测量和传感系统等领域。随着光纤技术各个领域的快速发展，对2×2单模光纤耦合器的性能也提出了越来越高的要求。偏振特性是2×2单模光纤耦合器的一种重要的特性，其优劣直接影响到系统的性能。简要介绍了耦合器的制作工艺、保偏耦合器和偏振分束器、其它类型的光纤耦合器、以及由耦合器构成的器件。介绍了耦合模理论并推导了耦合系数；分析了拉制工艺偏差对耦合器耦合效率的影响；给出了几种简化的模型：哑铃模型、抛物线模型和指数函数模型；分析了纤芯、光纤线性双折射对耦合器的影响。论文对耦合器输出端相位特性的研究内容包括：(1)在不考虑耦合器的双折射，但是考虑附加损耗的条件下，分析了两个输出端口之间的相位差。结果表明该相位差偏离不考虑损耗时的相位差，偏移量在3°以内。(2)在考虑光纤双折射的条件下，研究了直通臂输出光两个正交分量之间的相位差问题，给出了表达式，分析了工作波长、环境折射率和有效耦合长度等参数对该相位差的影响，并对其进行了仿真和实验研究。结果表明线偏振光输入时输出端输出椭圆偏振光。论文还应用偏振光学的方法分析了耦合器的分光比及各光学参量对分光比的影响；分析了环境温度变化对分光比的影响，随后进行了分光比温度实验。论文还推导了与偏振相关的耦合模方程组，得到了耦合器偏振态的演化规律；从偏振度的概念出发，研究了2×2单模光纤耦合器的偏振特性，给出了偏振度的表达式；并对各参量对偏振度的影响进行了分析。最后分析了环境温度对偏振度的影响，并进行了计算机仿真和实验研究。论文对2×2单模光纤耦合器及其相关器件的研制工作有一定的参考意义。更多还原

【Abstract】 2×2 single-mode fiber coupler is a kind of important fiber passive component, widely used in optical fiber communication, coherent light measurement and optical sensors. With the development of fiber technique in many fields, 2×2 single-mode fiber coupler is required to be of better performance. Polarization property is one of the most important properties, which influences the performance of the whole system.In this paper, the fabrication methods of single-mode fiber coupler, polarization-maintaining fiber coupler and fiber polarization beamsplitter, other kinds of the couplers, and the devices consists of coupler are introduced. The coupled mode theory is reviewed and the coupled coefficient is derived. The effect of the machining deviation during the fabrication process on the coupling ratio of fiber coupler is analyzed. Several brief models including a dumbbell model, a parabola model and an exponential model are given. Then the influences of the fiber core’s parameters and the coupler’s linear birefringence on the performance of a coupler are also theoretically analyzed.The investigations of the phase properties at the output ends of couplers include: (1) Under the condition of considering the coupler’s loss but not the fiber’s birefringence, the phase difference between the two output ends is studied. The results show that it shifts from the phase difference without considering the loss, and the shift is less than 3°. (2) Under the condition of taking account of the fiber’s birefringence, the phase retardance between the two orthogonal components at the end of the through-out arm, the mathematical expression is given and the influences of the working wavelength, the environment refractive index and the effective coupled length on the retardance are investigated, theoretically and experimentally. The results indicate that with a linear polarized light input, the output light will be an elliptical polarized light. In this paper employing the principles of polarization optics, the splitting ratio of a coupler is analyzed; the effects of fiber’s optical parameters upon the ration are also investigated. Then the influence of environment temperature on the ratio is researched theoretically and experimentally.The coupled mode equations concerning the polarization properties of couplers are derived; The matrices describing the polarization state variation are given. Exploiting the concept of DOP (Degree of Polarization), the polarization properties of 2×2 single mode fiber couplers are studied. The expression of the DOP at the output end of the throughout arm is given. The relations between the DOP and the parameters including effective coupled length, working wavelength, and the environment refractive index are simulated. Finally, the influences of environment temperature upon the DOP are investigated theoretically and experimentally.The work reported here might be helpful to the researchers working in fiber couplers research and fabrication techniques area.更多还原