Research On Dispersion Of Photonic Crystal Fiber

Photonic crystal fibers (PCFs), or holey fiber, have attracted more and more attention in past decades. Photonic crystal fibers have a microscopic array of air-holes that run along the fiber length. So far, PCFs with several appealing features, such as endless single mode, high nonlinearity, flat dispersion, large negative dispersion, etc., have been demonstrated. The PCFs possess remarkable dispersion properties which cannot be achieved in conventional single mode fiber due to their flexible structure design. Control of chromatic dispersion in PCFs is important for practical application in optical fiber communication, dispersion compensation, and nonlinear optics.In this thesis, we demonstrate a novel four-ring PCF with two defected rings and a central defected-core. The defected air hole in the core results in mutual compensation between the material dispersion and the waveguide dispersion. The optimization of the two defected rings can further tailor the dispersion curve and reduce the confinement losses. Through the study, we have employed the full-vector finite element method (FEM) to investigate the dispersion properties of the proposed PCF structure. Numerical simulation results show that the proposed four-ring PCF can have ultra-flattened dispersion of 0±0.23ps/km/nm in a 1.35-1.64μm wavelength range and the effective mode area can be as less as 18.49μm2 at 1.55μm. The proposed PCF with nearly zero ultra-flattened dispersion and small effective mode area around 1.55μm is suitable for the application of wavelength conversion, optical data transmission, optical parametric amplification, soliton pulse transmission, supercontinuum generation, and etc.