Metallic Halide Optical Glasses: Synthesis and Characterization of IR Transmitting Fluoride Glasses

In this thesis, heavy metal fluoride glasses based on ZrF4, HfF4 and BaF2/ThF4 have been studied. The ZrF4- and HfF4-based glasses exhibit considerable promise as high transparency materials from the UV to the IR (0.2 - 7 micro m) and the BaF2/ThF4-based glasses exhibit transparency over even a larger region (0.2-9 micro m). At present there are several problems associated with the usage of these glasses in high technology systems, and these have been the main motive for the present study. One major problem is that the materials are relatively poor glass formers and have a strong tendency to crystallize on cooling. Another is that absorption bands at 2.9 micro m and 7 or 9 micro m, due respectively to -OH and metal oxyfluoride impurities, can cause significant transmission losses in the mid-IR radiation, if they can not be eliminated or at least substantially reduced. These transmission characteristics are most important with regard to the potential telecommunication system applications of these glasses. Concerning these problems, it was apparent that they were essentially related to the quality of glasses which could be produced (with respect to their homogeneity and impurity levels).