Investigation of the drawing region in the production of Ge-S-I optical fibers for infrared applications

In the present work, series of Ge-S-I glass samples with 5, 10 and 15% of iodine and a concentration of germanium varying between 25 and 35% were prepared and their physical properties such as Tg, density, Visible and infrared light absorption were investigated. From the analysis of the properties close to the stoichiometric composition (GeS2)xI100-x, we propose an equation of composition that takes into account the effect of iodine as a structure modifier. A great change is observed in the band-gap and Tg values, both of which follow the (GeS2)X-(GeI4)1-X composition line. We report for the first time a study of the drawing ability of these glasses using a preform-to-fiber drawing technique, to obtain fibers with wide composition range. The results allow us to define a fiber drawing domain inside the glass forming region. We demonstrate that the fiber drawing region is located between two composition lines for which the Mean Coordination Number (MCN) values are 2.4 and 2.55. Attenuation losses measured at 1310 nm for some selected fibers range between 10.9 and 23.0 dB/m.