Theoretical And Experimental Study On Photonic-Band Gap Fibers

Photonic crystals are one type of the artificial crystal. Normally they are in the magnitude of wavelength and composed by two materials (even three or more), which are arranged periodically in one, two and three dimensional. Because of the Bragg diffraction, for a certain frequency-range, the light can not propagate, and the photonic bandgap will be formed.In the introduction, the current research situation on PCF summarized, and the background and the significance of our subject are emphasized. We briefly illustrate the definition and the development of PCF.For the purpose of introducing the numerical methods into computing the PCF, we expatiated on the two basic methods: PWM and FDTD, which provide strong support in theory to the modeling.In chapter 3, the bend loss property of long wave length cut is measured for several different Bragg fibers. Based on FDTD, the fiber structure is optimized, when the eigenmode propagation loss of Bragg fiber is the lowest. And the influence of fiber's geometrical structure to the bend loss property of long wave length cut is analyzed systemically.In chapter 4, using MPB, the modeling of different air-filling fraction for hollow-core bandgap photonic crystal fibers with triangular lattice. The distribution of defect mode and the properties of mode distribution are analyzed for the hollow-core bandgap photonic crystal fibers with air-filling fraction of 70%. Utilizing its unique dispersion properties, we compress the soliton mode-locked pulse from the fiber laser, and compared with the pulse compression by the grating.The result shows the advantages of the bandgap photonic crystal fibers for compressing pulse,and provides the possibility of all fiber system for laser and compressing pulse.