Structure Design And Property Analysis Of Novel Photonic Crystal Fibers

Due to flexible structure, photonic crystal fiber (PCF) has unique optical properties andwide application prospects. Thus, PCF has received extensive attention and become a researchhotspot in the field of optical communication. This thesis focuses on structure design andproperty analysis of hollow-core photonic bandgap fiber (HC-PBGF) and hybrid photoniccrystal fiber theoretically. The primary work could be described as follows:The influence of core surround doping on transmission properties of HC-PBGF isanalyzed. By doping high refractive index medium in core surround, the effect of differentdoping concentration on group velocity dispersion, core-confined energy, effective mode areaand the effective refractive index is studied. The results show that core surround doping canalter the transmission properties of HC-PBGF significantly which is an effective method tocontrol the transmission properties of HC-PBGF.Based on the core surround doping research, a new structure is proposed to improve thetemperature feature of HC-PBGF. The new structure merges high refractive index liquidcylinders into the surround of the fiber core. By using full-vector finite element method, theinfluence of temperature on the effective refractive index, core energy, effective mode area ofdifferent wavelength is obtained. The numerical results show that the proposed structureimproves the temperature sensitivity of the transmission properties, which makes HC-PBGFhave better temperature sensitive characteristics.A hybrid guiding single-polarization single-mode photonic crystal fiber is proposed. First,the bandgap range, effective refractive index and the mode field distribution of the proposedfiber are obtained by the full-vector finite element method. Then, combined with the resonantcoupling theory, the effect of hole pitch and high refractive cylinder size on thesingle-polarization single-mode property is studied. On the basis of above analysis, the fiberstructure parameters are optimized. Finally the single-polarization single-mode bandwidth ofthe proposed fiber is analyzed. The results show that the proposed fiber achieves effectivesingle-mode transmission in a wide band range including1.55μm, and eliminates the adverseeffect of polarization mode dispersion and polarization crosstalk.The study of this thesis establishes a theoretical foundation for the further research andpractical application of hollow-core photonic bandgap fiber and hybrid guidingsingle-polarization single-mode photonic crystal fiber.