Tellurite And Fluorotellurite Glasses For Active And Passive

6. Optical properties; MDO 239
Infrared spectroscopy of series 65 TeO2-(25-x)ZnF2-xZnO-10Na2O, for 5 ≤ x ≤ 30 mol. %
Fig. (6.36) shows the infrared spectra of glasses MOF009 to 013 which were part of the
series 65TeO2-(25-x)ZnF2-xZnO-10Na2O mol. %, for 5 ≤ x ≤ 25 mol. %. The OH bands
grew in intensity with increasing ZnO in these glasses. Fig. (6.37) to (6.41) shows the
Gaussian deconvolution of these glasses. It is interesting to note that the ZnF2 containing
glasses (MOF009 to MOF012, x = 5 to 20 mol. % ZnO) did not exhibit strongly H-
bonded OH, and only exhibited weakly H-bonded OH and free-OH bands. Only the oxide
glass, MOF013 (x = 25 mol. % ZnO), exhibited a strongly H-bonded OH band in addition
to the weakly H-bonded OH and free-OH. Fig. (6.42) shows the variation in intensity of
the OH band at around 2900 cm -1 with ZnO / ZnF2 ratio. For ZnO / ZnF2 = 0.2 (20 %
mol. ZnF2) the loss was around 15 dB.m -1 , which increased to around 240 dB.m -1 for
ZnO / ZnF2 = 1 (0 % mol. ZnF2). Fig. (6.43) shows all glasses had around the same
relative amount of free-OH (25 %). All fluoride containing glasses (MOF009 to
MOF012) contained around 75 % weakly H-bonded OH. The oxide glass (MOF013)
contained around 50 % weakly H-bonded OH and 25 % strongly H-bonded OH.
Comparison of infrared spectra of fluorotellurite glasses with a view to the manufacture
of low optical loss mid-infrared fibre
Glasses of the series (90-x)TeO2-10Na2O-xZnF2 mol. %, for 5 ≤ x ≤ 30 mol. %
(MOF001, 004 to 008) transmitted to around 6 µm, and when melted for 2 hours
exhibited OH absorption bands at 2900 cm -1 of around 0.02 cm -1 (20 dB.m -1 ) for x = 15 to