FLUOROPHOSPHATE CLADDING GLASSES FOR FLUORIDE GLASS-FIBERS

Fluorophosphate glasses have been investigated in NaPO3-ZnF2-PbF2-BaF2 systems. Stable glass-forming areas were determined when NaPO3 conten t was 30, 40 and 50 mol%. Glass characteristic temperatures, refractiv e index and thermal expansion coefficient were measured. Large variati ons are observed for n(D) and T-g depending on lead fluoride concentra tion. Anionic oxygen also increases n(D) and T-g values but decreases thermal expansion. The application of these glasses as cladding materi als for fluorozirconate, fluoroindate and cadmium fluorochloride glass es is discussed. Good chemical compatibility between a fluoroindate co re glass and a fluorophosphate cladding glass was observed by thermal analysis.