This paper presents the research on optimization of the splicing process in the electric arc of telecommunication optical fibers and erbium doped EDF fibers. The results of the calculations of diffusion coefficients GeO2 in telecommunication optical fibers and diffusion coefficients Er and Al2O3 (together) in the fiber EDF are presented. Diffusion coefficients were determined for the fusion temperature in the electric arc ≈2000°C, on the basis of changes, along the splice, of spliced thermoluminescence intensity profiles of the fibers. On the basis of knowledge of diffusion coefficients simulation calculation of loss joints of MC SMF fiber (Matched Cladding Single Mode Fiber - SiO2: GeO2) and NZDS SMF (Non Zero Dispersion Shifted - Single Mode Fiber - SiO2: GeO2) with EDF (Erbium Doped Fiber - SiO2: Al2O3, Er) was performed and presented as a function of diffusion time. Experimental studies of optimization of thermal connected MC SMF and NZDS SMF with EDF were presented and compared with theoretical results. This paper presents the results of microscopic observations of defects and diffusion, and X-ray microanalysis in the spliced areas of single-mode telecommunication optical fibers: MC SMF, NZDS-SMF and erbium doped active single mode optical fibers. Studies were performed with the use of the scanning electron microscope JSM5800LV and JSM6610A microscope equipped with EDS X-ray spectrometer. Results showing the influence of heating time on the diffusion of core dopants and the formation of deformations in the splice areas were presented.
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