Tellurite And Fluorotellurite Glasses For Active And Passive

2. Literature review; MDO 54
be broader and flatter than for silicate based glasses (1530 to 1640 nm and 1520 to 1600
nm respectively) [36].
Feng et al. [54] showed that addition of GeO2 and Y2O3 to erbium (III) doped TeO2-
GeO2-ZnO-Na2O-Y2O3 glasses, increased glass stability and the lifetime of 4 I13/2 level of
the Er +3 ion.
Shen et al. [55] showed that the replacement of ZnO and TeO2 with Na2O results in a
narrowing of the emission band of erbium (III). The lifetime of erbium (III) in TeO2-
Na2O-ZnO glasses reaches a maximum at 11000 ppmw Er +3 . Broadening of the 1.55 µm
emission also occurs with increasing Er2O3 content. High OH content decreases the
lifetimes of the 4 I13/2 4 I15/2 transition significantly [55]. Fibre drawn from this glass
exhibited minimum loss of around 0.5 dB.m -1 at 1.3 µm, however, losses increases
rapidly at lower and higher wavelengths. Fig. (2.13) shows the fibre loss spectra, with an
inset of the theoretical intrinsic loss curve.
Fig. (2.13): Loss spectra of Er +3 -doped TeO2-Na2O-ZnO fibre (inset shows theoretical
intrinsic loss curve) [55].