Erbium-doped multicomponent phosphate glass waveguides were deposited by rf sputtering techniques. The Er concentration was 5.3×1020 cm−3. By pumping the waveguide at 980 nm with a power of ∼21 mW, a net optical gain of 4.1 dB at 1.535 μm was achieved. This high gain per unit length at low pump power could be achieved because the Er–Er cooperative upconversion interactions in this heavily Er-doped phosphate glass are very weak [the upconversion coefficient is (2.0±0.5)×10−18 cm3/s], presumably due to the homogeneous distribution of Er in the glass and due to the high optical mode confinement in the waveguide which leads to high pump power density at low pump power.

No abstract

No abstract

Equations which describe incongruent nucleation and subsequent crystal growth have been derived. A ZrF4-BaF2-LaF3-AIF3-NaF glass was used to test the validity of these equations. Nucleation rate measurements were fitted to theory and some growth rate measurements were found in reasonable agreement with theoretical predictions. Both nucleation theory and crystal growth theory were used for computer simulations of the crystallization behaviour during heat treatments. Some heat treatments were performed in a differential scanning calorimeter to verify the theories. The experimental results were in good agreement with the numerical data. Using these theoretical results it is possible to estimate fibre scattering losses due to crystallization. Depending on drawing temperature, estimated losses can vary from 0.01 4 (310~ to 25 (320~ or more dB km -1

No abstract