| Since 1990s, photonic crystal fibers (PCFs) have attracted a great deal of interest because of their unique advantages for controlling light. Some of these advantages include endless single-mode guidance, highly adjustable effective mode area and nonlinearity, engineered dispersion at visible and near-infrared wavelengths, and high birefringence. In particular, the high birefringence has been applied in many fields, such as the polarization -maintaining (PM) PCF, polarization splitter or coupler, optical sensing, high birefringent polarization-related components. So the research on PCFs has a very importantly academic and applied significance.Combining our research on the National "973" plan of China, we haveinvestigated several problems in this dissertation, which are related to theresearch on PCF. First, we investigate the influence of the structuralparameters and air-hole distributing in PCFs' cladding on the PCFs'characteristics. Then we present a new concept of "squeezing ratio"(SR) todescribe the squeezed degree of PCFs' lattices. The PCFs with squeezedtriangular lattice and rectangle lattice are simulated and analyzed with thisSR model. Moreover, we introduce a novel component and modify thecapillary staking method to fabricate the squeezed PCFs. Last but not least,we focus on the applications of PCF in polarization mode dispersion (PMD)compensation. The main innovations of this dissertation are list as follows:Five triangular-lattice highly birefringent PCFs with different air-holedistributing are analyzed. Several properties of them, such as the PCF'smodal field, the birefringence and the dispersion, are simulated by thesupercell lattice method. Moreover, a comparison is made among them tostudy the impact of air-holes configuration of PCFs on their propagationproperties. The simulation results show that air-holes at differentposition have different impact on the propagation properties of PCFs.Based on our research results, we cooperate with Wuhan Academy of Post and Telecom in drawing a polarization-maintaining PCF. After solving some key technologic problems, we draw a highly birefringent PCF. This PCF's birefringence is 7.8×10-3.The concept of SR is presented to describe the squeezed degree of PCF lattice, for the first time to our knowledge. Based on this concept, the squeezing ratio model is presented, which is the first theoretical model that can describe and analyze the PCFs with not only the squeezed triangular lattice but also the rectangle lattice. The research results show that PCFs are birefringent due to the squeezing of PCF lattice. Then, we analyze the dependence of the SR and the structural parameters, such as the air-hole diameter, incidence wavelength and the lattice constants, on the birefringence of the squeezed PCFs.A modified stacking method based on the capillary stacking technique is presented, for the first time to our knowledge, which helps to design and fabricate photonic crystal fibers with squeezed lattice. The squeezing ratio of PCFs changes if adjusting the zigzag component introduced in this paper, which is a major advantage over the traditional capillary stacking technique. The influences of the structural parameters of the zigzag component on the squeezing ratio are discussed. Moreover, the birefringence characteristics of such squeezed PCFs are simulated using the supercell lattice method.The applications of PCF are investigated. The PM-PCF fabricated ourselves is used in the PMD compensationor in the optic-fiber communication. The degree of polarization (DOP) is monitored as the feedback signal of the PMD compensationor. The joint problem between PCF and single mode fiber is investigated and solved. Moreover, we discuss the influence of polarization dependent loss on DOP.
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