Property Analysis And Optimized Design Of Photonic Crystal Fibers

Photonic crystal fiber is one kind of photonic crystal, which consists of transverseperiodic arranged air holes with line defect and made of single material. Comparedwith the traditional optical fiber, photonic crystal fibers have excellent opticalproperties compared with the traditional optical fibers due to their flexible structuredesign. The PCFs can be divided into three types depending on the method of theguided light: totally internal reflection photonic crystal fibers (TIR-PCFs), photonicbandgap photonic crystal fibers (PBG-PCFs) and Hybrid-guiding Photonic CrystalFibers（HG-PCFs）. The transmission property of PCFs closely relates to its structureparameters, therefore, the study of the structure of the PCFs has great practicalsignificance on the transmission characteristics. The main contents are as follows:We analyze the nonlinear coefficient and dispersion property on the differentarrangement of the cladding and structural parameters by using the full vector finiteelement method. The results show that TIR-PCF of hexagonal structure has a betterperformance on nonlinear property than square structure. The dispersion property ofthe PCFs can also be altered by changing the fiber structure parameters. A newstructure of TIR-PCF is proposed whose nonlinear coefficient can be as high as0.172m1.w1. The range of flat dispersion can be between0.7~0.95μm. Such a PCFcan be used for the optical device.Also, we analyze the band-gaps range and mode field distribution of theHG-PCFs through theoretical and numerical simulation methods. The effects ofdispersion property and effective mode area by changing the high refractive cylindersize, diameter of core and hole pitch are studied. The numerical results show that theproposed structure has the ability of achieving flat dispersion effectively. Thedispersion keeps at27.24±1for the wavelength range of1.25-1.60m, andthe mode area is15.801m2at1.550m.Our results have important reference value for further research and relevantapplications of TIR-PCFs and HG-PCFs in all-fiber devices and fiber lasers.