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The Research On Supercontinuum In Nonlinear Fibers

Posted on:2008-05-24Degree:MasterType:Thesis
Country:ChinaCandidate:Q WangFull Text:PDF
GTID:2178360272467113Subject:Optical Engineering
Abstract/Summary:PDF Full Text Request
When a strong and short pulse transmits in a nonlinear medium, the nonlinear effects such as Self Phase Modulation, Cross Phase Modulation, Stimulated Raman Scattering, the Four Wave Mixing and the linear effect Group Velocity Dispersion, work together and make the pulse more broad. This phenomenon is the production of supercontinuum (SC). Since the supercontinuum first to be found in the fiber, the research about it never stops. The study on supercontinuum has gone through three stages: from the single mode fibers to tapered fibers to photonic crystal fibers (PCF). Because of the good dispersion characteristic and flexible design method of photonic crystal fiber, PCF becomes the first choice to make the SC. Based on the theory, this paper mainly simulate the production of SC in a PCF.The main contents as following: first from the Maxwell equations, I got the generalized nonlinear Schrodinger equation which describes a pulse transmission in a fiber. And then took use of the split-step Fourier method to solve this equation, improved it on symmetrical split-step Fourier method for higher precision, and at last discussed the problems which may occur in the simulation process. Base on this, numerically simulated the production of SC. For the parameters which affect the SC, this paper also have a detailed introduction. The main parameters'effect such as fiber length, the initial chirp, the pulse width and the peak power all to be analyzed. From the simulation, we found that the broadening of SC has three stages: the initial broadening stage, the dramatic broadening stage and the saturation broadening stage. The effect of each parameter is different. In order to get a more flat and broad SC, we should select the proper parameter. And at the same time we found that the production of SC is different between the normal dispersion region and the abnormal dispersion region. The abnormal dispersion region is better for the production of broad SC. In the end of this paper, I put forward a method which took use of two fibers to produce the SC. This method has been proved valid.
Keywords/Search Tags:Supercontinuum (SC), Nonlinear Fiber (NF), Nonlinear Schrodinger Equation, Split-step Fourier Method
PDF Full Text Request
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