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Simulation Study Of Method Of Restraining Mode Competition Based On Four-Wave-Mixing In Multi-Wavelength Fiber Laser

Posted on:2011-08-02Degree:MasterType:Thesis
Country:ChinaCandidate:Y L YaoFull Text:PDF
GTID:2178360332958206Subject:Physical Electronics
Abstract/Summary:PDF Full Text Request
With the rapid development of optical communication technology, highperformance lasers are in great demand. During all kinds of lasers, fiber laser hasreceived more and more attention from all over the world because of itsdistinguished advantages, such as complete compatibility to opticalcommunication system, high output power and tenability and being theappropriate light source of long-distance, high-capacity, ultra-high-speedcommunication system. The DWDM (Dense Wavelength Division Multiplexing)technology, which is one of the core technologies in fiber communication,actively demands wideband multiwavelength laser light sources, and the loopcavity erbium-doped fiber laser is a promising one.The previous research in multiwavelength erbium-doped fiber laser oftenfocused on C band or L band separately, so the output was not able to meet thedemand of modern wideband fiber communication system. Furthermore, lots ofthem used expensive device such as fiber gratings and photon crystal fiber. Andcutting down the cost will be a big problem.This paper introduces a new design scheme of multiwavelength EDFL,which has two loop cavities and a special feedback mechanism. Gain is easilyexpanded to C+L band by using multilevel pumps, and multiwavelength output isstable. Mode competition is restrained by FWM produced by dispersion switchedfiber and the channel space is controlled by tunable fiber filter. Then we will getmultiwavelength output accord with ITU standard.Then we analyze fiber laser cavity, derive the series of rate equations andpropagation equations. Next we build up the theoretical model and a series ofequations of restraining mode competition based on the FWM (four wave mixing)theory. We detailedly introduce the method of calculating laser output by usingthis theoretical model, and advance the algorithm. Since the initial values ofbackward ASE (amplified spontaneous emission) are known only at the end of thegain medium, the initial value at starting point are difficult to get. To solve thisproblem we introduce the so-called shooting method. Then by omitting somecomplicated conditions, we do simulations and get series of multiwavelengthoutput power spectrum. We analyze the simulation results with theoretical resultsand find the influence law of pumping power and length of nonlinear fiber. Inaddition, this thesis points out the outlooks of our work.
Keywords/Search Tags:fiber laser, multi-wavelength laser, dual-loop cavity laser, four-wave-mixing
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