Fabrication of low-loss infrared-transmitting chalcogenide optical fibers

This dissertation examined the physical, optical, and thermal properties of two types of infrared transmitting optical fibers. The first type is As-S-Se based fibers which transmit in the mid-infrared (1--7 m m). The second type is Ge-As-Se-Te based fibers which transmit in the infrared (2--11 m m). By changing the Se and Te content in the As-S-Se and Ge-As-Se-Te glass systems, respectively, physical, optical, and thermal properties can be tailored so that sulfide and telluride glass fibers can be fabricated to meet requirements for specific applications. Investigation of the structures in multicomponent Ge-As-Se-Te and Ge-As-Se-Te-I glass systems provided an understanding of relationships between physical and optical properties. By combining the physical, optical, and thermal properties with new purification and glass processing techniques, low loss of sulfide and telluride optical fibers have been fabricated for numerous IR applications.; The sulfide glass fiber has a large optical gap energy and small free carrier absorption. These contributed to a negligible change in the absorption loss with respect to temperature, d( Da )/dT, between 2 and 5 m m for -90°C ≤ T ≤ 70°C. The telluride glass fiber has a smaller optical gap energy and a larger free carrier absorption loss. Thus, its d( Da )/dT is relatively large between -60°C and 60°C. Dielectric constant measurements indicated that the relative dielectric constant of both glasses increases as the content of larger ions like Se and Te increases due to enhanced electronic polarization. Reactions between the sulfide glass melt and the quartz ampoule were studied. This led to better glass processing techniques that yielded low loss on long length fibers. In addition, a new process of utilizing microwave energy to remove physiadsorped OH- and H2O species at the fiber/Teflon coating was developed to minimize the effect of static fatigue between fiber drawing and cabling on the strength of sulfide and telluride fibers.