Design of Yb3+ doped laser for industrial application.

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Simpungwe, Moses
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The University of Zambia
The design and development of ytterbium-doped fibre lasers (YDFLs) operating around 1018nm laser wavelength and pumped around 976nm has advanced in technology since the first ytterbium laser was tested in 1988. The fiber lasers are used in various sectors such as communications, material processing, medical to mention but a few. Laser designers have the great objective of ensuring that the parameters such as pump power, active fibre cable and ion concentration are optimized for better quality laser output power. Further, the right choice of the output coupling between the Dichroic mirror (DM) and Fibre Bragg Grating (FBG) help eradicate the challenges faced in laser device design in terms of power output. Previous studies have reported use of diode lasers operating around 976nm as pump sources and lasing around 1018nm. There are, however, few reports on pump source use of 980nm on ytterbium doped laser fibre in the literature. This study therefore sought to contribute to improving on the power output of the YDFLs operating in continuous wave (CW) mode. In this modeling, a 980nm wavelength pump source with a lasing value at 1018nm wavelength and Dichroic couplers are deployed. In modeling the Yb3+ doped Laser, a quantitative approach was used. Linear differential equations were solved in order to determine the optimized values for the variables. Simulations using Computer software simulation -MATLAB were conducted. Power output of 59.64W was achieved against pump power of 68W, giving a slope efficiency of 87.71%. The operational characteristics of this Yb3+ doped fiber laser device in bidirectional pumping promises significant applications in radar, laser machining, free space communication and medical treatment. The results, further, show that the fiber cable length, the ion concentration and the choice of reflectivity on the OC and HR are critical when designing a fiber laser. Based on the results from the model, this study recommends that a study of the model be conducted experimentally to ascertain if the theoretical results will match with the experimental results.
Thesis of Masters of Engineering in Telecommunications Systems.