A process is developed to make potassium ion-exchanged waveguides in e
rbium-ytterbium co-doped phosphate glasses. The effects of pump and si
gnal wavelengths, and of the waveguide length on the gain in the waveg
uides are investigated. At a signal wavelengthof 1.530 mu m, 19.5dB in
ternal gain is achieved in a 6mm long waveguide; the measured noise fa
ctor is 4dB.