الفهرس 
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Abstract
Erbium-doped fiber amplifiers (EDFA) are the pivotal equipment’s in all-optical
networks. The length of the silicate fiber used in traditional EDFA is often up to several meters
because of the low pump absorption efficiency, which is a great drawback in miniature and
integration. In order to realize an EDFA in a scale of a few centimeters, the concentration of Er3+
must be extremely high. Unfortunately, concentration quenching will appear when the
concentration of Er3+ exceeds 1025 ions/m3 because of severe ion-ion interactions. Researches
indicate that the problem can be solved by co-doping with Yb3+ and selecting phosphate glasses
as the host materials. This system is called erbium-ytterbium (Er3+/Yb3+) co-doped waveguide
amplifiers (EYCDWA). The absorption cross-section of Yb3+ is about one order of magnitude
higher than that of Er3+.
The Yb3+ will absorb most of pump light and efficiently transfer the absorbed energy to
Er3+. The solubility of rare-earth ions in phosphate glasses is very high and the energy transfer
efficiency from Yb3+ to Er3+ can be as high as 95% because of the large phonon energy in
phosphate glasses. The gain and noise figure characteristics of Er3+/Yb3+ co-doped phosphate
waveguide amplifiers were studied in this thesis. The cooperative up-conversion and crossrelaxation
occurred at high Er3+ doped concentration and the energy transfer from Yb3+ to Er3+ at
Er3+/Yb3+ co-doped materials were investigated in five-level rate equations.