Study On Characteristics Of Band-Gap Photonic Crystal Fibers

The band-gap photonic fibers (BPGFs) origin from the photonic crystals. Unliketraditional fiber which guides light by total internal reflection, the BPGFs guide light byband-gap effect. The BPGFs have many potential applications because of its advancedcharacters such as low loss, manageable disperison, controlable nonlinearity, etc.For BPGFs, the bandwidth is decided by the band-gap, the transmission distance isdecided by the loss and the distortion is decided by the dispersion. The band-gap, lossand dispersion of BPGFs are investigated in the thesis, which will provide theoreticalbasis for drawing this fiber and have important guiding significance.Firstly, the band-gap of the BPGFs is studied by plane wave expansion method(PWEM) and Finite Difference Time Domain (FDTD). It analyzes the effects of thestructure factors to the band-gap of BPGFs such as pitch (Λ), fiber cladding holediameter (d), filling ratio (d/Λ), the refractive index difference between claddingbackground and graded-index doped performs or air hole and cladding lattice style. Theresults can be applied to design the transimission band of BPGFs and to guide BPGFsdesigna in real applications.Secondly, the loss of the BPGFs (mainly focused on Solid Core BPGFs) isanalyzed by full vectors Finite Element Methods (FEM). It analyzes the effects of thestructure factors to the fibers loss, such as cladding up-doped performs ring numbers,filling ratio (d/Λ), refractive index difference(Δn) and the air hole in cladding. It canprovide a reference to design ultra-low loss solid core band-gap photonic crystal Fibers(SC-BPGFs).Finally, the dispersion of the BPGFs is studied. The effects of structure factors onthe dispersion (mainly focused on square-lattices SC-BPGFs) are studied, such asup-doped performs diameter (d) and center-to-center spacing (Λ), Based on the study ofthe effect, an improved SC-BPGFs (also called all-solid band-gap photonic crystalFibers) is realized which has a zero dispersion wavelength at1.55μm. It’ll find potentialapplications for SC-BPGFs in optical networking.