Tellurite And Fluorotellurite Glasses For Active And Passive

8. Fibre drawing; MDO 330
8. Fibre drawing
The properties most significant to fibre drawing (glass viscosity and the stress in a core /
clad fibre) are reported here. The fibre drawing parameters are shown for preforms
fibreised. The defects present in, and optical loss of pulled fibres will then be discussed.
Recommendations for the possibility of reducing the optical loss in fluorotellurite fibre
further in future work will then be given.
8.1. Experimental
8.1.1. Thermal mechanical analysis (TMA)
A Perkin Elmer TMA7 was used to obtain viscosity and thermal expansion data in this
study, using the parallel plate viscometry method [1]. This method was validated with a
standard sample (National Bureau of Standards sample no. 710) over the 10 5 to 10 7.5 Pa.s
viscosity range (the region close to the glass transition temperature, Tg, and the fibre
drawing temperature, Tη). The instrument consisted of a sample chamber, inside a
furnace, with an articulated silica pushrod. The sample dimensions were a disc of
diameter 5 mm, and thickness (h) 2 to 3 mm. A stainless steel foot was attached to the
pushrod, and the sample was placed on a stainless steel base in the sample chamber. A
force of 250 mN was applied to the pushrod, which was calibrated using electronic
scales. This force, and the force of the steel foot were recorded, giving the total force, F,