step, the effect of Ag
+ ion concentration on the excitation spectra and emission of SGB
doped with 0.2Eu 2 O 3 glasses was examined. As a result of the excitation of the glasses
with radiation at 394 nm, an 8% enhancement of europium ion luminescence signal
for
5 D 0 !
7 F 2 (616 nm) transition was obtained in glasses doped with 0.1 mol% of
AgNO 3 with respect to non-Ag
0 glasses resulting from plasmon resonance phenomenon and energy transfer (Fig. 14.14). In other cases, the quenching of luminescence associated with the backward energy transfer Ag
0
← Eu
3+ was observed. In
the next step, the glass with the highest level of luminescence underwent a heating
process at 360 °C at various time intervals (Fig. 14.15). As a result, an increase in the
luminescence intensity in the glasses annealed for 2 h, suggesting a progressive
thermal reduction of silver ions in the glass and thus increasing the effect of the
resulting Ag
0 nanoparticles with neighboring Eu
3+ ions by plasmon resonance was
observed. Finally, to produce the optical fibers, the classic method of drawing of the
preform was applied.
Figure 14.11 inset shows a comparison of changing luminescence spectra for
glass fiber co-doped with 0.1AgNO 3 /0.2Eu 2 O 3 annealed under analogous conditions as a bulk sample. Analyzing the obtained spectra, it is worth to notice that the
transformation of glass into fiber did not bring significant differences in the character of luminescence, which suggests good thermal stability of the fabricated SGB
glasses. The only difference is a larger change in luminescence for glass samples
annealed for 1 h, for which similar value was observed in the optical fiber for a
sample annealed for 2 h. This effect is related to the additional process of thermal
influence on the glass during the fiber drawing process. The experiment with
annealing the glass fiber also brought an unexpected result. Namely, when
annealing fibers with a molar content of 0.6%, a thin film with a characteristic
amber coloration formed on their surface. Performing measurements of absorption
Fig. 14.14 Luminescence spectra of SGB glasses for various concentrations of silver ions
440
J. Zmojda et al.
+ ion concentration on the excitation spectra and emission of SGB
doped with 0.2Eu 2 O 3 glasses was examined. As a result of the excitation of the glasses
with radiation at 394 nm, an 8% enhancement of europium ion luminescence signal
for
5 D 0 !
7 F 2 (616 nm) transition was obtained in glasses doped with 0.1 mol% of
AgNO 3 with respect to non-Ag
0 glasses resulting from plasmon resonance phenomenon and energy transfer (Fig. 14.14). In other cases, the quenching of luminescence associated with the backward energy transfer Ag
0
← Eu
3+ was observed. In
the next step, the glass with the highest level of luminescence underwent a heating
process at 360 °C at various time intervals (Fig. 14.15). As a result, an increase in the
luminescence intensity in the glasses annealed for 2 h, suggesting a progressive
thermal reduction of silver ions in the glass and thus increasing the effect of the
resulting Ag
0 nanoparticles with neighboring Eu
3+ ions by plasmon resonance was
observed. Finally, to produce the optical fibers, the classic method of drawing of the
preform was applied.
Figure 14.11 inset shows a comparison of changing luminescence spectra for
glass fiber co-doped with 0.1AgNO 3 /0.2Eu 2 O 3 annealed under analogous conditions as a bulk sample. Analyzing the obtained spectra, it is worth to notice that the
transformation of glass into fiber did not bring significant differences in the character of luminescence, which suggests good thermal stability of the fabricated SGB
glasses. The only difference is a larger change in luminescence for glass samples
annealed for 1 h, for which similar value was observed in the optical fiber for a
sample annealed for 2 h. This effect is related to the additional process of thermal
influence on the glass during the fiber drawing process. The experiment with
annealing the glass fiber also brought an unexpected result. Namely, when
annealing fibers with a molar content of 0.6%, a thin film with a characteristic
amber coloration formed on their surface. Performing measurements of absorption
Fig. 14.14 Luminescence spectra of SGB glasses for various concentrations of silver ions
440
J. Zmojda et al.